Release v1.19.5

* Allow directory listings to be pre-computed
* Do not require struct modules to be loaded

The current implementation would require us to
recompute protocols whenever a struct changed,
something that is not currently available.
Furthermore, the fact we had to load modules
naturally made consolidation more expensive.
Therefore we need a lazy type resolution,
and until we have such feature, we will only
track struct names.

.formatter.exs

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 [
   inputs: [
     "lib/*/{lib,scripts,unicode,test}/**/*.{ex,exs}",

.gitattributes

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 lib/elixir/test/elixir/fixtures/*.txt text eol=lf
 *.ex diff=elixir
 *.exs diff=elixir

.github/ISSUE_TEMPLATE/config.yml

@@ -1,3 +1,6 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
 ---
 blank_issues_enabled: true
 

.github/ISSUE_TEMPLATE/issue.yml

@@ -1,3 +1,6 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
 ---
 name: Report an issue
 description:

.github/dependabot.yml

@@ -1,3 +1,6 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
 version: 2
 updates:
   - package-ecosystem: "github-actions"

.github/workflows/ci-markdown.yml

@@ -1,3 +1,6 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
 name: CI for Markdown content
 
 on:
@@ -11,6 +14,9 @@ on:
       - "lib/**/*.md"
   workflow_dispatch:
 
+permissions:
+  contents: read
+
 jobs:
   lint:
     name: Lint Markdown content
@@ -22,12 +28,12 @@ jobs:
 
     steps:
       - name: Check out the repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           fetch-depth: 10
 
       - name: Run markdownlint
-        uses: DavidAnson/markdownlint-cli2-action@v18.0.0
+        uses: DavidAnson/markdownlint-cli2-action@992badcdf24e3b8eb7e87ff9287fe931bcb00c6e # v20.0.0
         with:
           globs: |
             lib/elixir/pages/**/*.md

.github/workflows/ci.yml

@@ -1,3 +1,6 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
 name: CI
 
 on:
@@ -18,29 +21,39 @@ permissions:
 
 jobs:
   test_linux:
-    name: Ubuntu 24.04, Erlang/OTP ${{ matrix.otp_version }}${{ matrix.deterministic && ' (deterministic)' || '' }}
+    name: Ubuntu 24.04, Erlang/OTP ${{ matrix.otp_version }}${{ matrix.deterministic && ' (deterministic)' || '' }}${{ matrix.coverage && ' (coverage)' || '' }}
     strategy:
       fail-fast: false
       matrix:
         include:
-          - otp_version: "27.1"
+          - otp_version: "28.1"
             deterministic: true
-          - otp_version: "27.1"
+          - otp_version: "28.1"
+            erlc_opts: "warnings_as_errors"
+            coverage: true
+          - otp_version: "28.1"
             otp_latest: true
+            erlc_opts: "warnings_as_errors"
+          - otp_version: "27.3"
+            erlc_opts: "warnings_as_errors"
           - otp_version: "27.0"
+            erlc_opts: "warnings_as_errors"
           - otp_version: "26.0"
-          - otp_version: "25.3"
-          - otp_version: "25.0"
           - otp_version: master
             development: true
           - otp_version: maint
             development: true
     runs-on: ubuntu-24.04
+    # Earlier Erlang/OTP versions ignored compiler directives
+    # when using warnings_as_errors. So we only set ERLC_OPTS
+    # from Erlang/OTP 27+.
+    env:
+      ERLC_OPTS: ${{ matrix.erlc_opts || '' }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           fetch-depth: 50
-      - uses: erlef/setup-beam@v1
+      - uses: erlef/setup-beam@8aa8a857c6be0daae6e97272bb299d5b942675a4 # v1.19.0
         with:
           otp-version: ${{ matrix.otp_version }}
       - name: Set ERL_COMPILER_OPTIONS
@@ -60,6 +73,11 @@ jobs:
       - name: Elixir test suite
         run: make test_elixir
         continue-on-error: ${{ matrix.development }}
+        env:
+          COVER: "${{ matrix.coverage }}"
+      - name: "Calculate Coverage"
+        run: make cover | tee "$GITHUB_STEP_SUMMARY"
+        if: "${{ matrix.coverage }}"
       - name: Build docs (ExDoc main)
         if: ${{ matrix.otp_latest }}
         run: |
@@ -68,7 +86,8 @@ jobs:
           cd ex_doc
           ../elixir/bin/mix do local.rebar --force + local.hex --force + deps.get + compile
           cd ../elixir/
-          make docs
+          git fetch --tags
+          DOCS_OPTIONS="--warnings-as-errors" make docs
       - name: Check reproducible builds
         if: ${{ matrix.deterministic }}
         run: |
@@ -76,20 +95,26 @@ jobs:
           # Recompile System without .git
           cd lib/elixir && ../../bin/elixirc -o ebin lib/system.ex && cd -
           taskset 1 make check_reproducible
+      - name: "Upload Coverage Artifact"
+        if: "${{ matrix.coverage }}"
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
+        with:
+          name: TestCoverage
+          path: cover/*
 
   test_windows:
     name: Windows Server 2019, Erlang/OTP ${{ matrix.otp_version }}
     strategy:
       matrix:
-        otp_version: ["25.3", "26.2", "27.3"]
+        otp_version: ["26.2", "27.3", "28.1"]
     runs-on: windows-2022
     steps:
       - name: Configure Git
         run: git config --global core.autocrlf input
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           fetch-depth: 50
-      - uses: erlef/setup-beam@v1
+      - uses: erlef/setup-beam@8aa8a857c6be0daae6e97272bb299d5b942675a4 # v1.19.0
         with:
           otp-version: ${{ matrix.otp_version }}
       - name: Compile Elixir
@@ -101,17 +126,17 @@ jobs:
       - name: Check format
         run: make test_formatted && echo "All Elixir source code files are properly formatted."
       - name: Erlang test suite
-        run: make --keep-going test_erlang
+        run: make test_erlang
       - name: Elixir test suite
         run: |
           Remove-Item 'c:/Windows/System32/drivers/etc/hosts'
-          make --keep-going test_elixir
+          make test_elixir
 
   check_posix_compliant:
     name: Check POSIX-compliant
     runs-on: ubuntu-24.04
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           fetch-depth: 50
       - name: Install Shellcheck
@@ -123,3 +148,27 @@ jobs:
           shellcheck -e SC2039,2086 bin/elixir && echo "bin/elixir is POSIX compliant"
           shellcheck bin/elixirc && echo "bin/elixirc is POSIX compliant"
           shellcheck bin/iex && echo "bin/iex is POSIX compliant"
+
+  license_compliance:
+    name: Check Licence Compliance
+
+    runs-on: ubuntu-24.04
+
+    steps:
+      - name: Use HTTPS instead of SSH for Git cloning
+        id: git-config
+        shell: bash
+        run: git config --global url.https://github.com/.insteadOf ssh://git@github.com/
+
+      - name: Checkout project
+        id: checkout
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+
+      - name: "Run OSS Review Toolkit"
+        id: ort
+        uses: ./.github/workflows/ort
+        with:
+          upload-reports: true
+          fail-on-violation: true
+          report-formats: "WebApp"
+          version: "${{ github.sha }}"

.github/workflows/notify.exs

@@ -1,4 +1,8 @@
 # #!/usr/bin/env elixir
+
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
 [tag] = System.argv()
 
 Mix.install([

.github/workflows/notify.yml

@@ -1,3 +1,6 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
 name: Notify
 
 on:
@@ -13,10 +16,10 @@ jobs:
     runs-on: ubuntu-latest
     name: Notify
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           fetch-depth: 50
-      - uses: erlef/setup-beam@v1
+      - uses: erlef/setup-beam@8aa8a857c6be0daae6e97272bb299d5b942675a4 # v1.19.0
         with:
           otp-version: "27.3"
           elixir-version: "1.18.3"

.github/workflows/ort/action.yml

@@ -0,0 +1,109 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
+name: "Run OSS Review Toolkit"
+description: "Runs OSS Review Toolkit & generates SBoMs"
+inputs:
+  report-formats:
+    description: "ORT Report Formats"
+    required: true
+  fail-on-violation:
+    description: "Whether to fail on violation."
+    required: false
+    default: false
+  upload-reports:
+    description: "Whether to upload all reports"
+    required: false
+    default: false
+  version:
+    description: "Elixir Version (Tag / SHA)"
+    required: true
+
+outputs:
+  results-path:
+    description: "See oss-review-toolkit/ort-ci-github-action action"
+    value: "${{ steps.ort.outputs.results-path }}"
+  results-sbom-cyclonedx-xml-path:
+    description: "See oss-review-toolkit/ort-ci-github-action action"
+    value: "${{ steps.ort.outputs.results-sbom-cyclonedx-xml-path }}"
+  results-sbom-cyclonedx-json-path:
+    description: "See oss-review-toolkit/ort-ci-github-action action"
+    value: "${{ steps.ort.outputs.results-sbom-cyclonedx-json-path }}"
+  results-sbom-spdx-yml-path:
+    description: "See oss-review-toolkit/ort-ci-github-action action"
+    value: "${{ steps.ort.outputs.results-sbom-spdx-yml-path }}"
+  results-sbom-spdx-json-path:
+    description: "See oss-review-toolkit/ort-ci-github-action action"
+    value: "${{ steps.ort.outputs.results-sbom-spdx-json-path }}"
+
+runs:
+  using: "composite"
+  steps:
+    - name: Fetch Default ORT Config
+      id: fetch-default-ort-config
+      uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      with:
+        repository: oss-review-toolkit/ort-config
+        ref: "main"
+        path: ".ort-config"
+
+    - name: Setup ORT Config
+      id: setup-ort-config
+      shell: bash
+      run: |
+        mkdir -p "/$HOME/.ort/"
+
+        # Move Fetched Default Config into Place
+        mv .ort-config "$HOME/.ort/config"
+        
+        # Append Global ORT Config
+        cat .ort/config/config.yml >> "$HOME/.ort/config/config.yml"
+        
+        # Override Default Evaluator Rules
+        cp .ort/config/evaluator.rules.kts "$HOME/.ort/config/evaluator.rules.kts"
+
+        # Add Package Configurations
+        mkdir -p "$HOME/.ort/config/package-configurations/SpdxDocumentFile/The Elixir Team"
+        for FILE in .ort/package-configurations/*.yml; do
+          COMPONENT="$(basename "$FILE")"
+          cp "$FILE" "$HOME/.ort/config/package-configurations/SpdxDocumentFile/The Elixir Team/$COMPONENT"
+          sed -i -E \
+            "s/(\"SpdxDocumentFile:The Elixir Team:.+:)\"/\1${ELIXIR_VERSION}\"/" \
+            "$HOME/.ort/config/package-configurations/SpdxDocumentFile/The Elixir Team/$COMPONENT"
+        done
+
+        # Set Version in SPDX & Config
+        sed -i "s/# elixir-version-insert/versionInfo: '${ELIXIR_VERSION}'/" project.spdx.yml
+        sed -i -E "s/(\"SpdxDocumentFile:The Elixir Team:.+:)\"/\1${ELIXIR_VERSION}\"/" .ort.yml
+        sed -i "s|https://github.com/elixir-lang/elixir.git|${ELIXIR_REPO}@${ELIXIR_VERSION}|" project.spdx.yml
+      env:
+        ELIXIR_VERSION: "${{ inputs.version }}"
+        ELIXIR_REPO: "${{ github.server_url }}/${{ github.repository }}.git"
+
+    - name: "Cache ScanCode"
+      uses: actions/cache@d4323d4df104b026a6aa633fdb11d772146be0bf # v4.2.2
+      with:
+        path: "~/.cache/scancode-tk"
+        key: ${{ runner.os }}-scancode
+
+    - name: Run OSS Review Toolkit
+      id: ort
+      uses: oss-review-toolkit/ort-ci-github-action@1805edcf1f4f55f35ae6e4d2d9795ccfb29b6021 # v1.1.0
+      with:
+        image: ghcr.io/oss-review-toolkit/ort-minimal:65.0.0
+        run: >-
+          labels,
+          cache-dependencies,
+          cache-scan-results,
+          analyzer,
+          scanner,
+          advisor,
+          evaluator,
+          reporter,
+          ${{ inputs.upload-reports == 'true' && 'upload-results' || '' }}
+        fail-on: "${{ inputs.fail-on-violation == 'true' && 'violations,issues' || '' }}"
+        report-formats: "${{ inputs.report-formats }}"
+        ort-cli-report-args: >-
+          -O CycloneDX=output.file.formats=json,xml
+          -O SpdxDocument=outputFileFormats=JSON,YAML
+        sw-version: "${{ inputs.version }}"

.github/workflows/release.yml

@@ -1,3 +1,6 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
 name: Release
 
 on:
@@ -13,13 +16,13 @@ env:
   LANG: C.UTF-8
 
 permissions:
-  contents: write
-  id-token: write
-  attestations: write
+  contents: read
 
 jobs:
   create_draft_release:
     runs-on: ubuntu-22.04
+    permissions:
+      contents: write
     env:
       GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
     steps:
@@ -33,7 +36,7 @@ jobs:
             --draft \
             ${{ github.ref_name }}
 
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         if: github.ref_type == 'branch'
         with:
           fetch-depth: 50
@@ -55,20 +58,24 @@ jobs:
           git push origin $ref_name --force
 
   build:
+    name: "Build Elixir"
+
     strategy:
       fail-fast: true
       matrix:
         include:
-          - otp: 25
-            otp_version: "25.3"
           - otp: 26
             otp_version: "26.0"
           - otp: 27
             otp_version: "27.0"
+          - otp: 28
+            otp_version: "28.0"
             build_docs: build_docs
+
     runs-on: ubuntu-22.04
+
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           fetch-depth: 50
 
@@ -79,49 +86,38 @@ jobs:
           otp: ${{ matrix.otp }}
           build_docs: ${{ matrix.build_docs }}
 
-      - name: "Attest docs provenance"
-        uses: actions/attest-build-provenance@v2
-        id: attest-docs-provenance
-        if: ${{ matrix.build_docs }}
-        with:
-          subject-path: "Docs.zip"
-      - name: "Copy docs provenance"
-        if: ${{ matrix.build_docs }}
-        run: cp "$ATTESTATION" Docs.zip.sigstore
-        env:
-          ATTESTATION: "${{ steps.attest-docs-provenance.outputs.bundle-path }}"
-
       - name: Create Docs Hashes
-        if: ${{ matrix.build_docs }}
+        if: matrix.build_docs
         run: |
           shasum -a 1   Docs.zip > Docs.zip.sha1sum
           shasum -a 256 Docs.zip > Docs.zip.sha256sum
 
       - name: "Upload linux release artifacts"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: build-linux-elixir-otp-${{ matrix.otp }}
           path: elixir-otp-${{ matrix.otp }}.zip
 
       - name: "Upload windows release artifacts"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: build-windows-elixir-otp-${{ matrix.otp }}
           path: elixir-otp-${{ matrix.otp }}.exe
 
       - name: "Upload doc artifacts"
-        uses: actions/upload-artifact@v4
-        if: ${{ matrix.build_docs }}
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
+        if: matrix.build_docs
         with:
           name: Docs
           path: Docs.zip*
 
   sign:
     needs: [build]
+    environment: release
     strategy:
       fail-fast: true
       matrix:
-        otp: [25, 26, 27]
+        otp: [26, 27, 28]
         flavor: [windows, linux]
 
     env:
@@ -129,38 +125,36 @@ jobs:
 
     runs-on: ${{ matrix.flavor == 'linux' && 'ubuntu-22.04' || 'windows-2022' }}
 
+    permissions:
+      contents: write
+      id-token: write
+
     steps:
-      - uses: actions/download-artifact@v4
+      - name: "Download build"
+        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4.3.0
         with:
           name: build-${{ matrix.flavor }}-elixir-otp-${{ matrix.otp }}
 
+      - name: Log in to Azure
+        if: ${{ matrix.flavor == 'windows' && vars.AZURE_TRUSTED_SIGNING_ACCOUNT_NAME }}
+        uses: azure/login@a457da9ea143d694b1b9c7c869ebb04ebe844ef5 # v2.3.0
+        with:
+          client-id: ${{ secrets.AZURE_CLIENT_ID }}
+          tenant-id: ${{ secrets.AZURE_TENANT_ID }}
+          subscription-id: ${{ secrets.AZURE_SUBSCRIPTION_ID }}
       - name: "Sign files with Trusted Signing"
-        if: github.repository == 'elixir-lang/elixir' && matrix.flavor == 'windows'
-        uses: azure/trusted-signing-action@v0.5.0
+        uses: azure/trusted-signing-action@0d74250c661747df006298d0fb49944c10f16e03 # v0.5.1
+        if: ${{ matrix.flavor == 'windows' && vars.AZURE_TRUSTED_SIGNING_ACCOUNT_NAME }}
         with:
-          azure-tenant-id: ${{ secrets.AZURE_TENANT_ID }}
-          azure-client-id: ${{ secrets.AZURE_CLIENT_ID }}
-          azure-client-secret: ${{ secrets.AZURE_CLIENT_SECRET }}
           endpoint: https://eus.codesigning.azure.net/
-          trusted-signing-account-name: trusted-signing-elixir
-          certificate-profile-name: Elixir
+          trusted-signing-account-name: ${{ vars.AZURE_TRUSTED_SIGNING_ACCOUNT_NAME }}
+          certificate-profile-name: ${{ vars.AZURE_CERTIFICATE_PROFILE_NAME }}
           files-folder: ${{ github.workspace }}
           files-folder-filter: exe
           file-digest: SHA256
           timestamp-rfc3161: http://timestamp.acs.microsoft.com
           timestamp-digest: SHA256
 
-      - name: "Attest release provenance"
-        uses: actions/attest-build-provenance@v2
-        id: attest-provenance
-        with:
-          subject-path: ${{ env.RELEASE_FILE }}
-      - name: "Copy release .zip provenance"
-        shell: bash
-        run: cp "$ATTESTATION" "${RELEASE_FILE}.sigstore"
-        env:
-          ATTESTATION: "${{ steps.attest-provenance.outputs.bundle-path }}"
-
       - name: Create Release Hashes
         if: matrix.flavor == 'windows'
         shell: pwsh
@@ -179,20 +173,105 @@ jobs:
           shasum -a 256 "$RELEASE_FILE" > "${RELEASE_FILE}.sha256sum"
 
       - name: "Upload linux release artifacts"
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: sign-${{ matrix.flavor }}-elixir-otp-${{ matrix.otp }}
           path: ${{ env.RELEASE_FILE }}*
 
-  upload-release:
-    needs: [create_draft_release, build, sign]
-    runs-on: ubuntu-22.04
+  sbom:
+    name: Generate SBoM
+
+    needs: [build, sign]
+
+    runs-on: ubuntu-24.04
+
+    permissions:
+      contents: write
+      id-token: write
+      attestations: write
 
     steps:
-      - uses: actions/download-artifact@v4
+      - name: Use HTTPS instead of SSH for Git cloning
+        id: git-config
+        shell: bash
+        run: git config --global url.https://github.com/.insteadOf ssh://git@github.com/
+
+      - name: Checkout project
+        id: checkout
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+
+      - name: "Download Build Artifacts"
+        id: download-build-artifacts
+        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4.3.0
         with:
           pattern: "{sign-*-elixir-otp-*,Docs}"
           merge-multiple: true
+          path: /tmp/build-artifacts/
+
+      - name: "Run OSS Review Toolkit"
+        id: ort
+        uses: ./.github/workflows/ort
+        with:
+          report-formats: "CycloneDx,SpdxDocument"
+          version: "${{ github.ref_type	== 'tag' && github.ref_name || github.sha }}"
+
+      - name: Attest Distribution Assets with SBoM
+        id: attest-sbom
+        uses: actions/attest-sbom@115c3be05ff3974bcbd596578934b3f9ce39bf68 # v2.2.0
+        with:
+          subject-path: |
+            /tmp/build-artifacts/{elixir-otp-*.*,Docs.zip}
+            ${{ steps.ort.outputs.results-sbom-cyclonedx-xml-path }}
+            ${{ steps.ort.outputs.results-sbom-cyclonedx-json-path }}
+            ${{ steps.ort.outputs.results-sbom-spdx-yml-path }}
+            ${{ steps.ort.outputs.results-sbom-spdx-json-path }}
+          sbom-path: "${{ steps.ort.outputs.results-sbom-spdx-json-path }}"
+
+      - name: "Copy SBoM provenance"
+        id: sbom-provenance
+        shell: bash
+        run: |
+          mkdir attestations
+
+          for FILE in /tmp/build-artifacts/{elixir-otp-*.*,Docs.zip}; do
+            cp "$ATTESTATION" "attestations/$(basename "$FILE").sigstore"
+          done
+
+          cp "$ATTESTATION" "attestations/$(basename "${{ steps.ort.outputs.results-sbom-cyclonedx-xml-path }}").sigstore"
+          cp "$ATTESTATION" "attestations/$(basename "${{ steps.ort.outputs.results-sbom-cyclonedx-json-path }}").sigstore"
+          cp "$ATTESTATION" "attestations/$(basename "${{ steps.ort.outputs.results-sbom-spdx-yml-path }}").sigstore"
+          cp "$ATTESTATION" "attestations/$(basename "${{ steps.ort.outputs.results-sbom-spdx-json-path }}").sigstore"
+        env:
+          ATTESTATION: "${{ steps.attest-sbom.outputs.bundle-path }}"
+
+      - name: "Assemble Release SBoM Artifacts"
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
+        with:
+          name: "SBoM"
+          path: |
+            ${{ steps.ort.outputs.results-sbom-cyclonedx-xml-path }}
+            ${{ steps.ort.outputs.results-sbom-cyclonedx-json-path }}
+            ${{ steps.ort.outputs.results-sbom-spdx-yml-path }}
+            ${{ steps.ort.outputs.results-sbom-spdx-json-path }}
+
+      - name: "Assemble Distribution Attestations"
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
+        with:
+          name: "Attestations"
+          path: "attestations/*.sigstore"
+
+  upload-release:
+    needs: [create_draft_release, build, sign, sbom]
+    runs-on: ubuntu-22.04
+
+    permissions:
+      contents: write
+
+    steps:
+      - uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4.3.0
+        with:
+          pattern: "{sign-*-elixir-otp-*,Docs,SBoM,Attestations}"
+          merge-multiple: true
 
       - name: Upload Pre-built
         shell: bash
@@ -217,23 +296,27 @@ jobs:
             elixir-otp-*.exe.sigstore \
             Docs.zip \
             Docs.zip.sha{1,256}sum \
-            Docs.zip.sigstore
+            Docs.zip.sigstore \
+            bom.*
 
   upload-builds-hex-pm:
     needs: [build, sign]
     runs-on: ubuntu-22.04
     concurrency: builds-hex-pm
+    environment: release
     env:
       AWS_ACCESS_KEY_ID: ${{ secrets.HEX_AWS_ACCESS_KEY_ID }}
       AWS_SECRET_ACCESS_KEY: ${{ secrets.HEX_AWS_SECRET_ACCESS_KEY }}
-      AWS_REGION: ${{ secrets.HEX_AWS_REGION }}
-      AWS_S3_BUCKET: ${{ secrets.HEX_AWS_S3_BUCKET }}
-      FASTLY_REPO_SERVICE_ID: ${{ secrets.HEX_FASTLY_REPO_SERVICE_ID }}
-      FASTLY_BUILDS_SERVICE_ID: ${{ secrets.HEX_FASTLY_BUILDS_SERVICE_ID }}
-      FASTLY_KEY: ${{ secrets.HEX_FASTLY_KEY }}
-      OTP_GENERIC_VERSION: "25"
+      AWS_REGION: ${{ vars.HEX_AWS_REGION }}
+      AWS_S3_BUCKET: ${{ vars.HEX_AWS_S3_BUCKET }}
     steps:
-      - uses: actions/download-artifact@v4
+      - name: "Check if variables are set up"
+        if: "${{ ! vars.HEX_AWS_REGION }}"
+        run: |
+          echo "Required variables for uploading to hex.pm are not set up, skipping..."
+          exit 1
+
+      - uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4.3.0
         with:
           pattern: "{sign-*-elixir-otp-*,Docs}"
           merge-multiple: true
@@ -246,6 +329,8 @@ jobs:
         run: |
           ref_name=${{ github.ref_name }}
 
+          oldest_otp=$(find . -type f -name 'elixir-otp-*.zip' | sed -r 's/^.*elixir-otp-([[:digit:]]+)\.zip$/\1/' | sort -n | head -n 1)
+
           for zip in $(find . -type f -name 'elixir-otp-*.zip' | sed 's/^\.\///'); do
             dest=${zip/elixir/${ref_name}}
             surrogate_key=${dest/.zip$/}
@@ -255,7 +340,7 @@ jobs:
               --metadata "{\"surrogate-key\":\"builds builds/elixir builds/elixir/${surrogate_key}\",\"surrogate-control\":\"public,max-age=604800\"}"
             echo "builds/elixir/${surrogate_key}" >> purge_keys.txt
 
-            if [ "$zip" == "elixir-otp-${OTP_GENERIC_VERSION}.zip" ]; then
+            if [ "$zip" == "elixir-otp-${oldest_otp}.zip" ]; then
               aws s3 cp "${zip}" "s3://${AWS_S3_BUCKET}/builds/elixir/${ref_name}.zip" \
                 --cache-control "public,max-age=3600" \
                 --metadata "{\"surrogate-key\":\"builds builds/elixir builds/elixir/${ref_name}\",\"surrogate-control\":\"public,max-age=604800\"}"
@@ -288,6 +373,8 @@ jobs:
           date="$(date -u '+%Y-%m-%dT%H:%M:%SZ')"
           ref_name=${{ github.ref_name }}
 
+          oldest_otp=$(find . -name 'elixir-otp-*.zip.sha256sum' | sed -r 's/^.*elixir-otp-([[:digit:]]+)\.zip\.sha256sum$/\1/' | sort -n | head -n 1)
+
           aws s3 cp "s3://${AWS_S3_BUCKET}/builds/elixir/builds.txt" builds.txt || true
           touch builds.txt
 
@@ -298,7 +385,7 @@ jobs:
             sed -i "/^${ref_name}-${otp_version} /d" builds.txt
             echo -e "${ref_name}-${otp_version} ${{ github.sha }} ${date} ${build_sha256} \n$(cat builds.txt)" > builds.txt
 
-            if [ "${otp_version}" == "otp-${OTP_GENERIC_VERSION}" ]; then
+            if [ "${otp_version}" == "otp-${oldest_otp}" ]; then
               sed -i "/^${ref_name} /d" builds.txt
               echo -e "${ref_name} ${{ github.sha }} ${date} ${build_sha256} \n$(cat builds.txt)" > builds.txt
             fi
@@ -337,3 +424,7 @@ jobs:
           for key in $(cat purge_keys.txt); do
             purge "${key}"
           done
+        env:
+          FASTLY_REPO_SERVICE_ID: ${{ secrets.HEX_FASTLY_REPO_SERVICE_ID }}
+          FASTLY_BUILDS_SERVICE_ID: ${{ secrets.HEX_FASTLY_BUILDS_SERVICE_ID }}
+          FASTLY_KEY: ${{ secrets.HEX_FASTLY_KEY }}

.github/workflows/release_pre_built/action.yml

@@ -1,3 +1,6 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
 name: "Release pre built"
 description: "Builds elixir release, ExDoc and generates docs"
 inputs:
@@ -10,7 +13,7 @@ inputs:
 runs:
   using: "composite"
   steps:
-    - uses: erlef/setup-beam@v1
+    - uses: erlef/setup-beam@5304e04ea2b355f03681464e683d92e3b2f18451 # v1.18.2
       with:
         otp-version: ${{ inputs.otp_version }}
         version-type: strict
@@ -42,7 +45,7 @@ runs:
           ref=v$(curl -s https://hex.pm/api/packages/ex_doc | jq --raw-output '.latest_stable_version')
         fi
         echo "EX_DOC_REF=$ref" >> $GITHUB_ENV
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       if: ${{ inputs.build_docs }}
       with:
         repository: elixir-lang/ex_doc

.gitignore

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 /doc/
 /lib/*/ebin/
 /lib/*/_build/
@@ -11,3 +15,4 @@
 /.eunit
 .elixir.plt
 erl_crash.dump
+/cover/

.markdownlint.jsonc

@@ -1,3 +1,6 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: 2021 The Elixir Team
+
 {
   // Consecutive header levels (h1 -> h2 -> h3). We don't care about this.
   "MD001": false,

.ort.yml

@@ -0,0 +1,118 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
+excludes:
+  paths:
+    - pattern: "man/*"
+      reason: "DOCUMENTATION_OF"
+      comment: "Documentation"
+    - pattern: ".github/**/*"
+      reason: "BUILD_TOOL_OF"
+      comment: "Documentation"
+    - pattern: ".ort/**/*"
+      reason: "BUILD_TOOL_OF"
+      comment: "Documentation"
+
+    # Unfortunately we'll have to repeat all package level excludes here
+    # Make sure to keep them in sync with the package configuration in
+    # .ort/package-configurations
+    - pattern: "lib/*/pages/**/*"
+      reason: "DOCUMENTATION_OF"
+      comment: "Documentation"
+    - pattern: "lib/*/test/**/*"
+      reason: "TEST_OF"
+      comment: "Tests"
+    - pattern: "lib/*/scripts/**/*"
+      reason: "BUILD_TOOL_OF"
+      comment: "Build Tool"
+    - pattern: "lib/*/examples/**/*"
+      reason: "EXAMPLE_OF"
+      comment: "Example"
+
+curations:
+  license_findings:
+    # Version File
+    - path: "VERSION"
+      reason: "NOT_DETECTED"
+      comment: "Apply Trademark Policy to VERSION file"
+      detected_license: "NONE"
+      concluded_license: "Apache-2.0"
+
+    # Wrongly Identified
+    - path: ".gitignore"
+      reason: "INCORRECT"
+      comment: "Ignored by ScanCode"
+      detected_license: "NONE"
+      concluded_license: "Apache-2.0"
+    - path: ".gitattributes"
+      reason: "INCORRECT"
+      comment: "Ignored by ScanCode"
+      detected_license: "NONE"
+      concluded_license: "Apache-2.0"
+    - path: "CONTRIBUTING.md"
+      reason: "INCORRECT"
+      comment: "Wrongly identified TSL license"
+      detected_license: "Apache-2.0 OR NOASSERTION OR LicenseRef-scancode-tsl-2020"
+      concluded_license: "Apache-2.0"
+    - path: "OPEN_SOURCE_POLICY.md"
+      reason: "INCORRECT"
+      comment: "Wrongly identified NOASSERTION"
+      detected_license: "NOASSERTION"
+      concluded_license: "Apache-2.0"
+
+    # Unfortunately we'll have to repeat all package level license curations here
+    # Make sure to keep them in sync with the package configuration in
+    # .ort/package-configurations
+
+    # Test Fixtures
+    - path: "lib/*/test/fixtures/**/*"
+      reason: "NOT_DETECTED"
+      comment: "Apply default license to test fixtures"
+      detected_license: "NONE"
+      concluded_license: "Apache-2.0"
+
+    # Logos
+    - path: "lib/elixir/pages/images/logo.png"
+      reason: "NOT_DETECTED"
+      comment: "Apply Trademark Policy to Elixir Logo"
+      detected_license: "NONE"
+      concluded_license: "LicenseRef-elixir-trademark-policy"
+    - path: "lib/elixir/scripts/windows_installer/assets/Elixir.ico"
+      reason: "NOT_DETECTED"
+      comment: "Apply Trademark Policy to Elixir Logo"
+      detected_license: "NONE"
+      concluded_license: "LicenseRef-elixir-trademark-policy"
+
+    # Documentation Images
+    - path: "lib/elixir/pages/images/**/*.png"
+      reason: "NOT_DETECTED"
+      comment: "Apply default license to all images"
+      detected_license: "NONE"
+      concluded_license: "Apache-2.0"
+
+    # Test Fixtures
+    - path: "lib/elixir/test/elixir/fixtures/**/*"
+      reason: "NOT_DETECTED"
+      comment: "Apply default license to test fixtures"
+      detected_license: "NONE"
+      concluded_license: "Apache-2.0"
+
+    # Unicode
+    - path: "lib/elixir/unicode/*.txt"
+      reason: "NOT_DETECTED"
+      comment: "Apply default license to unicode files"
+      detected_license: "NONE"
+      concluded_license: "LicenseRef-scancode-unicode"
+
+    # Wrongly Identified
+    - path: "lib/elixir/pages/references/library-guidelines.md"
+      reason: "INCORRECT"
+      comment: |
+        The guide mentions multiple licenses for users to choose from.
+        It however is not licensed itself by the mentioned licenses.
+      concluded_license: "Apache-2.0"
+    - path: "lib/elixir/scripts/windows_installer/.gitignore"
+      reason: "INCORRECT"
+      comment: "Ignored by ScanCode"
+      detected_license: "NONE"
+      concluded_license: "Apache-2.0"

.ort/config/config.yml

@@ -0,0 +1,21 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
+ort:
+  enableRepositoryPackageCurations: true
+  enableRepositoryPackageConfigurations: true
+
+  scanner:
+    skipConcluded: false
+    includeFilesWithoutFindings: true
+
+  analyzer:
+    allowDynamicVersions: true
+    enabledPackageManagers: [SpdxDocumentFile]
+
+  reporter:
+    reporters:
+      SpdxDocument:
+        options:
+          creationInfoOrganization: The Elixir Team
+          documentName: "Elixir Source SPDX Document"

.ort/config/evaluator.rules.kts

@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2019 The ORT Project Authors (see <https://github.com/oss-review-toolkit/ort/blob/main/NOTICE>)
+ * Copyright (c) 2021 The Elixir Team
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+ // Docs: https://oss-review-toolkit.org/ort/docs/configuration/evaluator-rules
+
+val whitelistedLicenses = listOf(
+  // License for Elixir & Imported Erlang Projects
+  "Apache-2.0",
+  // License for the Elixir Logo
+  "LicenseRef-elixir-trademark-policy",
+  "LicenseRef-scancode-elixir-trademark-policy",
+  // License for included Unicode Files
+  "LicenseRef-scancode-unicode",
+  // DCO for committers
+  "LicenseRef-scancode-dco-1.1"
+).map { SpdxSingleLicenseExpression.parse(it) }.toSet()
+
+fun PackageRule.howToFixDefault() = """
+      * Check if this license violation is intended
+      * Adjust evaluation rules in `.ort/config/evaluator.rules.kts`
+    """.trimIndent()
+
+fun PackageRule.LicenseRule.isHandled() =
+  object : RuleMatcher {
+    override val description = "isHandled($license)"
+
+    override fun matches() = license in whitelistedLicenses
+  }
+
+fun RuleSet.unhandledLicenseRule() = packageRule("UNHANDLED_LICENSE") {
+  // Do not trigger this rule on packages that have been excluded in the .ort.yml.
+  require {
+    -isExcluded()
+  }
+
+  // Define a rule that is executed for each license of the package.
+  licenseRule("UNHANDLED_LICENSE", LicenseView.CONCLUDED_OR_DECLARED_AND_DETECTED) {
+    require {
+      -isExcluded()
+      -isHandled()
+    }
+
+    // Throw an error message including guidance how to fix the issue.
+    error(
+      "The license $license is currently not covered by policy rules. " +
+        "The license was ${licenseSource.name.lowercase()} in package " +
+        "${pkg.metadata.id.toCoordinates()}.",
+      howToFixDefault()
+    )
+  }
+}
+
+fun RuleSet.unmappedDeclaredLicenseRule() = packageRule("UNMAPPED_DECLARED_LICENSE") {
+  require {
+    -isExcluded()
+  }
+
+  resolvedLicenseInfo.licenseInfo.declaredLicenseInfo.processed.unmapped.forEach { unmappedLicense ->
+    warning(
+      "The declared license '$unmappedLicense' could not be mapped to a valid license or parsed as an SPDX " +
+        "expression. The license was found in package ${pkg.metadata.id.toCoordinates()}.",
+      howToFixDefault()
+    )
+  }
+}
+
+val ruleSet = ruleSet(ortResult, licenseInfoResolver, resolutionProvider) {
+  unhandledLicenseRule()
+  unmappedDeclaredLicenseRule()
+}
+
+ruleViolations += ruleSet.violations

.ort/package-configurations/eex.yml

@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
+id: "SpdxDocumentFile:The Elixir Team:eex:"
+path_excludes:
+  - pattern: "lib/eex/test/**/*"
+    reason: "TEST_OF"
+    comment: "Tests"
+license_finding_curations:
+  # Test Fixtures
+  - path: "lib/eex/test/fixtures/**/*"
+    reason: "NOT_DETECTED"
+    comment: "Apply default license to test fixtures"
+    detected_license: "NONE"
+    concluded_license: "Apache-2.0"

.ort/package-configurations/elixir.yml

@@ -0,0 +1,60 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
+id: "SpdxDocumentFile:The Elixir Team:elixir:"
+path_excludes:
+  - pattern: "lib/elixir/pages/**/*"
+    reason: "DOCUMENTATION_OF"
+    comment: "Documentation"
+  - pattern: "lib/elixir/scripts/**/*"
+    reason: "BUILD_TOOL_OF"
+    comment: "Build Tool"
+  - pattern: "lib/elixir/test/**/*"
+    reason: "TEST_OF"
+    comment: "Tests"
+license_finding_curations:
+  # Logos
+  - path: "lib/elixir/pages/images/logo.png"
+    reason: "NOT_DETECTED"
+    comment: "Apply Trademark Policy to Elixir Logo"
+    detected_license: "NONE"
+    concluded_license: "LicenseRef-elixir-trademark-policy"
+  - path: "lib/elixir/scripts/windows_installer/assets/Elixir.ico"
+    reason: "NOT_DETECTED"
+    comment: "Apply Trademark Policy to Elixir Logo"
+    detected_license: "NONE"
+    concluded_license: "LicenseRef-elixir-trademark-policy"
+
+  # Documentation Images
+  - path: "lib/elixir/pages/images/**/*.png"
+    reason: "NOT_DETECTED"
+    comment: "Apply default license to all images"
+    detected_license: "NONE"
+    concluded_license: "Apache-2.0"
+
+  # Test Fixtures
+  - path: "lib/elixir/test/elixir/fixtures/**/*"
+    reason: "NOT_DETECTED"
+    comment: "Apply default license to test fixtures"
+    detected_license: "NONE"
+    concluded_license: "Apache-2.0"
+
+  # Unicode
+  - path: "lib/elixir/unicode/*.txt"
+    reason: "NOT_DETECTED"
+    comment: "Apply default license to unicode files"
+    detected_license: "NONE"
+    concluded_license: "LicenseRef-scancode-unicode"
+
+  # Wrongly Identified
+  - path: "lib/elixir/pages/references/library-guidelines.md"
+    reason: "INCORRECT"
+    comment: |
+      The guide mentions multiple licenses for users to choose from.
+      It however is not licensed itself by the mentioned licenses.
+    concluded_license: "Apache-2.0"
+  - path: "lib/elixir/scripts/windows_installer/.gitignore"
+    reason: "INCORRECT"
+    comment: "Ignored by ScanCode"
+    detected_license: "NONE"
+    concluded_license: "Apache-2.0"

.ort/package-configurations/ex_unit.yml

@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
+id: "SpdxDocumentFile:The Elixir Team:exunit:"
+path_excludes:
+  - pattern: "lib/ex_unit/examples/**/*"
+    reason: "EXAMPLE_OF"
+    comment: "Example"
+  - pattern: "lib/ex_unit/test/**/*"
+    reason: "TEST_OF"
+    comment: "Tests"
+license_finding_curations:
+  # Test Fixtures
+  - path: "lib/ex_unit/test/fixtures/**/*"
+    reason: "NOT_DETECTED"
+    comment: "Apply default license to test fixtures"
+    detected_license: "NONE"
+    concluded_license: "Apache-2.0"

.ort/package-configurations/logger.yml

@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
+id: "SpdxDocumentFile:The Elixir Team:logger:"
+path_excludes:
+  - pattern: "lib/logger/test/**/*"
+    reason: "TEST_OF"
+    comment: "Tests"

.ort/package-configurations/mix.yml

@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
+id: "SpdxDocumentFile:The Elixir Team:mix:"
+path_excludes:
+  - pattern: "lib/mix/test/**/*"
+    reason: "TEST_OF"
+    comment: "Tests"
+license_finding_curations:
+  # Test Fixtures
+  - path: "lib/mix/test/fixtures/**/*"
+    reason: "NOT_DETECTED"
+    comment: "Apply default license to test fixtures"
+    detected_license: "NONE"
+    concluded_license: "Apache-2.0"

CHANGELOG.md

@@ -1,482 +1,508 @@
-# Changelog for Elixir v1.18
+<!--
+  SPDX-License-Identifier: Apache-2.0
+  SPDX-FileCopyrightText: 2021 The Elixir Team
+  SPDX-FileCopyrightText: 2012 Plataformatec
+-->
 
-Elixir v1.18 is an impressive release with improvements across the two main efforts happening within the Elixir ecosystem right now: set-theoretic types and language servers. It also comes with built-in JSON support and adds new capabilities to its unit testing library. Here is a quick break down.
+# Changelog for Elixir v1.19
 
 ## Type system improvements
 
-The most exciting change in Elixir v1.18 is type checking of function calls, alongside gradual inference of patterns and return types. To understand how this will impact your programs, consider the following code in "lib/user.ex":
+### Type checking of protocol dispatch and implementations
+
+This release also adds type checking when dispatching and implementing protocols.
+
+For example, string interpolation in Elixir uses the `String.Chars` protocol. If you pass a value that does not implement said protocol, Elixir will now emit a warning accordingly.
+
+Here is an example passing a range, which cannot be converted into a string, to an interpolation:
 
 ```elixir
-defmodule User do
-  defstruct [:age, :car_choice]
-
-  def drive(%User{age: age, car_choice: car}, car_choices) when age >= 18 do
-    if car in car_choices do
-      {:ok, car}
-    else
-      {:error, :no_choice}
-    end
-  end
-
-  def drive(%User{}, _car_choices) do
-    {:error, :not_allowed}
+defmodule Example do
+  def my_code(first..last//step = range) do
+    "hello #{range}"
   end
 end
 ```
 
-Elixir's type system will infer that the `drive/2` function expects a `%User{}` struct and returns either `{:ok, dynamic()}`, `{:error, :no_choice}`, or `{:error, :not_allowed}`.
+the above emits the following warnings:
 
-Therefore, the following code in a separate module (either in a separate or the same file), should emit a violation, due to an invalid argument:
+```
+warning: incompatible value given to string interpolation:
+
+    data
+
+it has type:
+
+    %Range{first: term(), last: term(), step: term()}
+
+but expected a type that implements the String.Chars protocol, it must be one of:
+
+    dynamic(
+      %Date{} or %DateTime{} or %NaiveDateTime{} or %Time{} or %URI{} or %Version{} or
+        %Version.Requirement{}
+    ) or atom() or binary() or float() or integer() or list(term())
+```
+
+Warnings are also emitted if you pass a data type that does not implement the `Enumerable` protocol as a generator to for-comprehensions:
 
 ```elixir
-User.drive({:ok, %User{}}, car_choices)
+defmodule Example do
+  def my_code(%Date{} = date) do
+    for(x <- date, do: x)
+  end
+end
 ```
 
-Here is the warning:
+will emit:
 
 ```
-    warning: incompatible types given to User.drive/2:
+warning: incompatible value given to for-comprehension:
 
-        User.drive({:ok, %User{age: nil, car_choice: nil}}, car_choices)
+    x <- date
+
+it has type:
+
+    %Date{year: term(), month: term(), day: term(), calendar: term()}
+
+but expected a type that implements the Enumerable protocol, it must be one of:
+
+    dynamic(
+      %Date.Range{} or %File.Stream{} or %GenEvent.Stream{} or %HashDict{} or %HashSet{} or
+        %IO.Stream{} or %MapSet{} or %Range{} or %Stream{}
+    ) or fun() or list(term()) or non_struct_map()
+```
+
+### Type checking and inference of anonymous functions
+
+Elixir v1.19 can now type infer and type check anonymous functions. Here is a trivial example:
+
+```elixir
+defmodule Example do
+  def run do
+    fun = fn %{} -> :map end
+    fun.("hello")
+  end
+end
+```
+
+The example above has an obvious typing violation, as the anonymous function expects a map but a string is given. With Elixir v1.19, the following warning is now printed:
+
+```
+    warning: incompatible types given on function application:
+
+        fun.("hello")
 
     given types:
 
-        {:ok, %User{age: nil, car_choice: nil}}, empty_list()
+        binary()
 
-    but expected one of:
+    but function has type:
 
-        dynamic(%User{age: term(), car_choice: term()}), dynamic()
-
-    where "car_choices" was given the type:
-
-        # type: empty_list()
-        # from: lib/foo.ex:21:17
-        car_choices = []
+        (dynamic(map()) -> :map)
 
     typing violation found at:
     │
- 22 │     User.drive({:ok, %User{}}, car_choices)
-    │          ~
+  6 │     fun.("hello")
+    │        ~
     │
-    └─ lib/foo.ex:22:10: Example.run/0
+    └─ mod.exs:6:8: Example.run/0
 ```
 
-> The mismatched arguments are shown in red, if your terminal supports ANSI coloring.
+Function captures, such as `&String.to_integer/1`, will also propagate the type as of Elixir v1.19, arising more opportunity for Elixir's type system to catch bugs in our programs.
 
-And the next snippet will warn because the `:error` clause will never match, as that's not a valid return type of the `User.drive/2` call:
+### Acknowledgements
+
+The type system was made possible thanks to a partnership between [CNRS](https://www.cnrs.fr/) and [Remote](https://remote.com/). The development work is currently sponsored by [Fresha](https://www.fresha.com/), [Starfish*](https://starfish.team/), and [Dashbit](https://dashbit.co/).
+
+## Faster compile times in large projects
+
+This release includes two compiler improvements that can lead up to 4x faster builds in large codebases.
+
+While Elixir has always compiled the given files in project or a dependency in parallel, the compiler would sometimes be unable to use all of the machine resources efficiently. This release addresses two common limitations, delivering performance improvements that scale with codebase size and available CPU cores.
+
+### Code loading bottlenecks
+
+Prior to this release, Elixir would load modules as soon as they were defined. However, because the Erlang part of code loading happens within a single process (the code server), this would make it a bottleneck, reducing parallelization, especially on large projects.
+
+This release makes it so modules are loaded lazily. This reduces the pressure on the code server and the amount of work during compilation, with reports of more than two times faster compilation for large projects. The benefits depend on the codebase size and the number of CPU cores available.
+
+Implementation wise, [the parallel compiler already acts as a mechanism to resolve modules during compilation](https://elixir-lang.org/blog/2012/04/24/a-peek-inside-elixir-s-parallel-compiler/), so we built on that. By making sure the compiler controls both module compilation and module loading, it can also better guarantee deterministic builds.
+
+There are two potential regressions with this approach. The first one happens if you spawn processes during compilation which invoke other modules defined within the same project. For example:
 
 ```elixir
-case User.drive(user, car_choices) do
-  {:ok, car} -> car
-  :error -> Logger.error("User cannot drive")
+defmodule MyLib.SomeModule do
+  list = [...]
+
+  Task.async_stream(list, fn item ->
+    MyLib.SomeOtherModule.do_something(item)
+  end)
 end
 ```
 
-And here is the warning:
+Because the spawned process is not visible to the compiler, it won't be able to load `MyLib.SomeOtherModule`. You have two options, either use `Kernel.ParallelCompiler.pmap/2` or explicitly call `Code.ensure_compiled!(MyLib.SomeOtherModule)` before spawning the process that uses said module.
 
-```
-    warning: the following clause will never match:
-
-        :error
-
-    because it attempts to match on the result of:
-
-        User.drive(user, car_choices)
-
-    which has type:
-
-        dynamic({:ok, term()} or {:error, :no_choice} or {:error, :not_allowed})
-
-    typing violation found at:
-    │
- 26 │       :error -> Logger.error("User cannot drive")
-    │       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-    │
-    └─ lib/foo.ex:26: Example.run/0
-```
-
-For more details on typing inference and the trade-offs made by the Elixir team, [see our official documentation](https://hexdocs.pm/elixir/1.18/gradual-set-theoretic-types.html#type-inference).
-
-There are many other improvements to the type system, which we will go in detail within the official release. Meanwhile, here is a list summary of the overall improvements done to the type system:
-
-* Type inference of patterns (typing inference of guards will be part of an upcoming release)
-
-* Type checking of all language constructs, including local and remote calls, except `for`, `with`, and closures
-
-* Type checking of all functions inlined by the compiler found in `Kernel`
-
-* Type checking of all conversion functions inlined by the compiler
-
-* [Support for tuples and lists as composite types](https://elixir-lang.org/blog/2024/08/28/typing-lists-and-tuples/) as well as type checking of their basic operations
-
-* Detection of clauses and patterns that will never match from `case`, `cond`, and `=`
-
-* Detection of unused clauses in private functions
-
-## ExUnit improvements
-
-ExUnit now supports parameterized tests to run the same test module multiple times under different parameters.
-
-For example, Elixir ships a local, decentralized and scalable key-value process storage called `Registry`. The registry can be partitioned and its implementation differs depending if partitioning is enabled or not. Therefore, during tests, we want to ensure both modes are exercised. With Elixir v1.18, we can achieve this by writing:
+The second one is related to `@on_load` callbacks (typically used for [NIFs](https://www.erlang.org/doc/system/nif.html)) that invoke other modules defined within the same project. For example:
 
 ```elixir
-defmodule Registry.Test do
-  use ExUnit.Case,
-    async: true,
-    parameterize: [
-      %{partitions: 1},
-      %{partitions: 8}
-    ]
+defmodule MyLib.SomeModule do
+  @on_load :init
 
-  # ... the actual tests ...
+  def init do
+    MyLib.AnotherModule.do_something()
+  end
+
+  def something_else do
+    ...
+  end
+end
+
+MyLib.SomeModule.something_else()
+```
+
+The reason this fails is because `@on_load` callbacks are invoked within the code server and therefore they have limited ability to load additional modules. It is generally advisable to limit invocation of external modules during `@on_load` callbacks but, in case it is strictly necessary, you can set `@compile {:autoload, true}` in the invoked module to address this issue in a forward and backwards compatible manner.
+
+Both snippets above could actually lead to non-deterministic compilation failures in the past, and as a result of these changes, compiling these cases are now deterministic.
+
+### Parallel compilation of dependencies
+
+This release introduces a variable called `MIX_OS_DEPS_COMPILE_PARTITION_COUNT`, which instructs `mix deps.compile` to compile dependencies in parallel.
+
+While fetching dependencies and compiling individual Elixir dependencies already happened in parallel, as outlined in the previous section, there were pathological cases where performance gains would be left on the table, such as when compiling dependencies with native code or dependencies where one or two large files would take most of the compilation time.
+
+By setting `MIX_OS_DEPS_COMPILE_PARTITION_COUNT` to a number greater than 1, Mix will now compile multiple dependencies at the same time, using separate OS processes. Empirical testing shows that setting it to half of the number of cores on your machine is enough to maximize resource usage. The exact speed up will depend on the number of dependencies and the number of machine cores, although some reports mention up to 4x faster compilation times. If you plan to enable it on CI or build servers, keep in mind it will most likely have a direct impact on memory usage too.
+
+## Improved pretty printing algorithm
+
+Elixir v1.19 ships with a new pretty printing implementation that tracks limits as a whole, instead of per depth. Previous versions would track limits per depth. For example, if you had a list of lists of 4 elements and a limit of 5, it would be pretty printed as follows:
+
+```elixir
+[
+  [1, 2, 3],
+  [1, 2, ...],
+  [1, ...],
+  [...],
+  ...
+]
+```
+
+This allows for more information to be shown at different nesting levels, which is useful for complex data structures. But it led to some pathological cases where the `limit` option had little effect on filtering the amount of data shown. The new implementation decouples the limit handling from depth, decreasing it as it goes. Therefore, the list above with the same limit in Elixir v1.19 is now printed as:
+
+```elixir
+[
+  [1, 2, 3],
+  ...
+]
+```
+
+The outer list is the first element, the first nested list is the second, followed by three numbers, reaching the limit. This gives developers more precise control over pretty printing.
+
+Given this may reduce the amount of data printed by default, the default limit has also been increased from 50 to 100. We may further increase it in upcoming releases based on community feedback.
+
+## Erlang/OTP 28 support
+
+Elixir v1.19 officially supports Erlang/OTP 28.1+ and later. In order to support the new Erlang/OTP 28 representation for regular expressions, structs can now control how they are escaped into abstract syntax trees by defining a `__escape__/1` callback.
+
+On the other hand, the new representation for regular expressions implies they can no longer be used as default values for struct fields. Instead of this:
+
+```elixir
+defmodule Foo do
+  defstruct regex: ~r/foo/
 end
 ```
 
-ExUnit parameterizes whole test modules. If your modules are configured to run concurrently, as above, so will the parameterized ones.
-
-ExUnit also comes with the ability of specifying test groups. While ExUnit supports running tests concurrently, those tests must not have shared state between them. However, in large applications, it may be common for some tests to depend on some shared state, and other tests to depend on a completely separate state. For example, part of your tests may depend on Cassandra, while others depend on Redis. Prior to Elixir v1.18, these tests could not run concurrently, but in v1.18 they might as long as they are assigned to different groups. Tests modules within the same group do not run concurrently, but across groups, they might.
-
-With features like async tests, suite partitioning, and now grouping, Elixir developers have plenty of flexibility to make the most use of their machine resources, both in development and in CI.
-
-## `mix format --migrate`
-
-The `mix format` command now supports an explicit `--migrate` flag, which will convert constructs that have been deprecated in Elixir to their latest version. Because this flag rewrites the AST, it is not guaranteed the migrated format will always be valid when used in combination with macros that also perform AST rewriting.
-
-As of this release, the following migrations are executed:
-
-  * Normalize parens in bitstring modifiers - it removes unnecessary parentheses in known bitstring modifiers, for example `<<foo::binary()>>` becomes `<<foo::binary>>`, or adds parentheses for custom modifiers, where `<<foo::custom_type>>` becomes `<<foo::custom_type()>>`.
-
-  * Charlists as sigils - formats charlists as `~c` sigils, for example `'foo'` becomes `~c"foo"`.
-
-  * `unless` as negated `if`s - rewrites `unless` expressions using `if` with a negated condition, for example `unless foo do` becomes `if !foo do`.
-
-More migrations may be added in future releases.
-
-## JSON support
-
-This release includes official support for JSON encoding and decoding.
-
-Both encoder and decoder fully conform to [RFC 8259](https://tools.ietf.org/html/rfc8259) and [ECMA 404](https://ecma-international.org/publications-and-standards/standards/ecma-404/) standards.
-
-### Encoding
-
-Encoding can be done via `JSON.encode!/1` and `JSON.encode_to_iodata!/1` functions. The default encoding rules are applied as follows:
-
-| **Elixir**                  | **JSON** |
-|-----------------------------|----------|
-| `integer() \| float()`      | Number   |
-| `true \| false `            | Boolean  |
-| `nil`                       | Null     |
-| `binary()`                  | String   |
-| `atom()`                    | String   |
-| `list()`                    | Array    |
-| `%{String.Chars.t() => _}`  | Object   |
-
-You may also implement the `JSON.Encoder` protocol for custom data structures. Elixir already implements the protocol for all Calendar types.
-
-If you have a struct, you can derive the implementation of the `JSON.Encoder` by specifying which fields should be encoded to JSON:
+You must do this:
 
 ```elixir
-  @derive {JSON.Encoder, only: [...]}
-  defstruct ...
+defmodule Foo do
+  defstruct [:regex]
+
+  def new do
+    %Foo{regex: ~r/foo/}
+  end
+end
 ```
 
-### Decoding
+## OpenChain certification
 
-Decoding can be done via `JSON.decode/2` and `JSON.decode!/2` functions. The default decoding rules are applied as follows:
+Elixir v1.19 is also our first release following OpenChain compliance, [as previously announced](https://elixir-lang.org/blog/2025/02/26/elixir-openchain-certification/). In a nutshell:
 
-| **JSON** | **Elixir**             |
-|----------|------------------------|
-| Number   | `integer() \| float()` |
-| Boolean  | `true \| false`        |
-| Null     | `nil`                  |
-| String   | `binary()`             |
-| Object   | `%{binary() => _}`     |
+  * Elixir releases now include a Source SBoM in CycloneDX 1.6 or later and SPDX 2.3 or later formats.
+  * Each release is attested along with the Source SBoM.
 
-## Language server listeners
+These additions offer greater transparency into the components and licenses of each release, supporting more rigorous supply chain requirements.
 
-4 months ago, we welcomed [the Official Language Server team](https://elixir-lang.org/blog/2024/08/15/welcome-elixir-language-server-team/), with the goal of unifying the efforts behind code intelligence, tools, and editors in Elixir. Elixir v1.18 brings new features on this front by introducing locks and listeners to its compilation. Let's understand what it means.
+This work was performed by [Jonatan Männchen](https://maennchen.dev) and sponsored by the [Erlang Ecosystem Foundation](https://erlef.org).
 
-At the moment, all language server implementations have their own compilation environment. This means that your project and dependencies during development are compiled once, for your own use, and then again for the language server. This duplicate effort could cause the language server experience to lag, when it could be relying on the already compiled artifacts of your project.
-
-This release address by introducing a compiler lock, ensuring that only a single operating system process running Elixir compiles your project at a given moment, and by providing the ability for one operating system process to listen to the compilation results of others. In other words, different Elixir instances can now communicate over the same compilation build, instead of racing each other.
-
-These enhancements do not only improve editor tooling, but they also directly benefit projects like IEx and Phoenix. For example, you can invoke `IEx.configure(auto_reload: true)` and IEx will automatically reload modules changed elsewhere, either by a separate terminal or your IDE.
-
-## Potential incompatibilities
-
-This release no longer supports WERL (a graphical user interface on Windows used by Erlang 25 and earlier). For a better user experience on Windows terminals, use Erlang/OTP 26+ (this is also the last Elixir release to support Erlang/OTP 25).
-
-Furthermore, in order to support inference of patterns, Elixir will raise if it finds recursive variable definitions. This means patterns that never match, such as this one, will no longer compile:
-
-    def foo(x = {:ok, y}, x = y)
-
-However, recursion of root variables (where variables directly point to each other), will also fail to compile:
-
-    def foo(x = y, y = z, z = x)
-
-While the definition above could succeed (as long as all three arguments are equal), the cycle is not necessary and could be removed, as below:
-
-    def foo(x = y, y = z, z)
-
-You may also prefer to write using guards:
-
-    def foo(x, y, z) when x == y and y == z
-
-## v1.18.4 (2025-05-21)
-
-This release includes initial support for Erlang/OTP 28, for those who want to try it out. In such cases, you may use Elixir v1.18.4 precompiled for Erlang/OTP 27, as it is binary compatible with Erlang/OTP 28.
-
-### 1. Enhancements
-
-#### IEx
-
-  * [IEx.Helpers] Add `IEx.Helpers.process_info/1` which prints process information
-
-#### Mix
-
-  * [mix compile] Support the `--no-listeners` option
-  * [mix local] Retry HTTP requests with disabled middlebox comp mode depending on the failure reason
-  * [mix local.hex] Install Hex per OTP release
-  * [mix local.rebar] Install Hex per OTP release
-  * [mix run] Support the `--no-listeners` option
-
-### 2. Bug fixes
-
-#### Elixir
-
-  * [Kernel] Emit trace events for `@on_definition` callbacks
-  * [Kernel] Emit trace events for `@on_load` callbacks
-  * [Kernel] Emit trace events for `super` calls
-  * [Kernel] Emit trace events for imported function calls
-  * [Kernel] Optimize map unions to avoid building long lists
-  * [Kernel] Do not crash when type checking nested bitstrings in patterns
-  * [Kernel] Do not crash when non-binary bitstring is given as struct default value
-  * [Kernel] Recompile regexes when escaped from module attributes for Erlang/OTP 28 compatibility
-  * [Kernel] Preserve backwards compatibility in `elixir_erl`
-
-#### Mix
-
-  * [mix deps.get] Ensure git checkout works when there are untracked files in the dependency
-  * [mix loadpaths] Do not run listeners when not checking the deps
-
-## v1.18.3 (2025-03-06)
+## v1.19.5 (2026-01-09)
 
 ### 1. Enhancements
 
 #### Elixir
 
-  * [JSON] Encode any JSON key to string
-  * [Kernel] Allow `<<_::3*8>>` in typespecs
-
-#### Mix
-
-  * [mix loadpaths] Support `--no-listeners` option
+  * [Protocol] Optimize protocol consolidation to no longer load structs
 
 ### 2. Bug fixes
 
 #### Elixir
 
-  * [CLI] Fix `--no-color` not setting `:ansi_enabled` to false
-  * [Protocol] Return correct implementation for an invalid struct pointing to `nil`
-  * [Stream] Do not raise when `Stream.cycle/1` is explicitly halted
-
-#### ExUnit
-
-  * [ExUnit.Diff] Fix regression when diffing nested improper lists
+  * [Kernel] Fix unnecessary recompilation when `dbg_callback` is modified at runtime
+  * [Kernel] Fix parser crash on missing parentheses on expression following operator `not in`
+  * [Kernel] Support fetching abstract code for modules compiled with Elixir v1.14 and earlier
+  * [Protocol] Ensure protocol consolidation no longer stores outdated struct types. As a consequence, protocols types only track struct names at the moment
+  * [Stream] Revert optimization which caused nested streams in `Stream.flat_map/2` to crash
 
 #### IEx
 
-  * [IEx.Autocomplete] Fix autocomplete crash when expanding struct with `__MODULE__`
-  * [IEx.Helpers] Do not purge on `recompile` if IEx is not running
+  * [IEx] Fix usage of `#iex:break` as part of multi-line prompts
 
-## v1.18.2 (2025-01-22)
+#### Logger
+
+  * [Logger.Backends] Do not crash on invalid metadata
+
+## v1.19.4 (2025-11-27)
+
+### 1. Enhancements
+
+#### Mix
+
+  * [mix xref] Add `--min-cycle-label` to help projects adapt to the more precise `mix xref graph` reports in Elixir v1.19. In previous versions, Elixir would break a large compilation cycle into several smaller ones, and therefore developers would check for `--min-cycle-size` on CI. However, the issue is not the size of the cycle (it has no implication in the amount of compiled files), but how many compile-time dependencies (aka compile labels) in a cycle. The new option allows developers to filter on the label parameter
+
+### 2. Bug fixes
+
+#### Elixir
+
+  * [File] Ensure `File.cp_r/3` reports non-existing destination properly (instead of source)
+
+#### ExUnit
+
+  * [ExUnit] Fix formatter crash when diffing takes too long
+  * [ExUnit] Ensure parallel matches in `assert` propagate type information
+
+#### Logger
+
+  * [Logger] Fix regression where formatter would crash when given chardata (the crash would happen when logging non-ASCII characters)
+
+#### Mix
+
+  * [mix help] Ensure `app:APP` works when the project or its dependencies were not yet compiled
+  * [mix escript.build] Ensure the `hex` application can be included in escripts
+
+## v1.19.3 (2025-11-13)
 
 ### 1. Enhancements
 
 #### Elixir
 
-  * [CLI] Add `--color`/`--no-color` for enabling and disabling of ANSI colors
-  * [Code.Fragment] Provide more AST context when invoking `container_cursor_to_quoted` with trailing fragments
-  * [Regex] Ensure compatibility with Erlang/OTP 28+ new Regex engine
+  * [Kernel] Support /E modifier for regular expressions in config files
 
 #### Mix
 
-  * [mix] Print compilation lock waiting message to stderr
-  * [mix] Add an environment variable to optionally disable compilation locking
+  * [mix compile] Allow forcing specific compilers, such as `--force-elixir`, `--force-app`, etc
+  * [mix help app:APP] Support showing helps for apps in Elixir and Erlang standard libraries
 
 ### 2. Bug fixes
 
 #### Elixir
 
-  * [CLI] Temporarily remove PowerShell scripts for `elixir`, `elixirc`, and `mix` on Windows, as they leave the shell broken after quitting Erlang
+  * [IO] Fix dialyzer warning on `IO.inspect :label`
 
 #### ExUnit
 
-  * [ExUnit] Fix crash when diffing bitstring specifiers
-
-#### IEx
-
-  * [IEx.Autocomplete] Fix crashing when autocompleting structs with runtime values
+  * [ExUnit.Case] Fix crash when formatting errors caused by a linked/trapped exit during `setup_all`
 
 #### Mix
 
-  * [mix] Track compilation locks per user to avoid permission errors
-  * [mix deps.update] Ensure Git dependencies can be upgraded by doing so against the origin
+  * [mix compile.app] Ensure functions in the format `&Mod.fun/arity` can be written to .app files
+  * [mix compile.app] Ensure strings with Unicode characters can be written to .app files
 
-## v1.18.1 (2024-12-24)
-
-### 1. Enhancements
-
-  * [Kernel] Do not emit type violation warnings when comparing or matching against literals
-  * [Kernel] Do not validate clauses of private overridable functions
-
-### 2. Bug fixes
-
-#### Elixir
-
-  * [Code.Fragment] Ensure `Code.Fragment.container_cursor_to_quoted/2` with `:trailing_fragment` parses expressions that were supported in previous versions
-  * [Kernel] Do not crash when typing violation is detected on dynamic dispatch
-  * [Kernel] Properly annotate the source for warnings emitted by the compiler with the `@file` annotation
-  * [Kernel] Properly annotate the source for warnings emitted by the type system with the `@file` annotation
-  * [Kernel] Remove `:no_parens` metadata when using capture with arity on all cases
-  * [Kernel] Ensure diagnostic traces are kept backwards compatible
-
-#### ExUnit
-
-  * [ExUnit.Case] Ensure async groups do not run concurrenly while the test suite is still loading
-  * [ExUnit.Case] Ensure `--repeat-until-failure` can be combined with groups
-
-#### Mix
-
-  * [mix compile.elixir] Store compilation results if compilation fails due to `--warnings-as-errors`
-  * [mix deps.loadpaths] Add build lock
-  * [mix escript.build] Ensure build succeeds when protocol consolidation is disabled
-  * [Mix.Shell] Ensure encoding is properly respected on Windows and Unix systems
-
-## v1.18.0 (2024-12-19)
+## v1.19.2 (2025-11-02)
 
 ### 1. Enhancements
 
 #### Elixir
 
-  * [CLI] Add experimental PowerShell scripts for `elixir`, `elixirc`, and `mix` on Windows. Those provide a safer entry point for running Elixir from other platforms
-  * [Calendar] Add `Duration.to_string/1`
-  * [Code] Support several migration options in `Code.format_string!/2`
-  * [Code] Add parenthesis around `--` and `---` in `Code.format_string!/2` to make precedence clearer
-  * [Code] Include more metadata in `Code.string_to_quoted/2` when `token_metadata: true` to help compute ranges from the AST
-  * [Code.Fragment] Have `:capture_arg` as its own entry in `Code.Fragment.surround_context/2`
-  * [Config] Add `Config.read_config/1`
-  * [Enumerable] Add `Enum.product_by/2` and `Enum.sum_by/2`
-  * [Exception] Add `MissingApplicationsError` exception to denote missing applications
-  * [JSON] Add a new `JSON` module with encoding and decoding functionality
-  * [JSON] Implement `JSON.Encoder` for all Calendar types
-  * [Kernel] Update source code parsing to match [UTS #55](https://www.unicode.org/reports/tr55/) latest recommendations. In particular, mixed script is allowed in identifiers as long as they are separate by underscores (`_`), such as `http_сервер`. Previously allowed highly restrictive identifiers, which mixed Latin and other scripts, such as the japanese word for t-shirt, `Tシャツ`, now require the underscore as well
-  * [Kernel] Warn on bidirectional confusability in identifiers
-  * [Kernel] Verify the type of the binary generators
-  * [Kernel] Track the type of tuples in patterns and inside `elem/2`
-  * [Kernel] Perform validation of root AST nodes in `unquote` and `unquote_splicing` to catch bugs earlier
-  * [Kernel] Add source, behaviour, and record information to Docs chunk metadata
-  * [Kernel] Support deterministic builds in tandem with Erlang by setting `ERL_COMPILER_OPTIONS=deterministic`. Keep in mind deterministic builds strip source and other compile time information, which may be relevant for programs
-  * [Kernel] Allow aliases and imports to be enabled conditionally in module body
-  * [List] Add `List.ends_with?/2`
-  * [Macro] Improve `dbg` handling of `if/2`, `with/1` and of code blocks
-  * [Macro] Add `Macro.struct_info!/2` to return struct information mirroring `mod.__info__(:struct)`
-  * [Registry] Add `Registry.lock/3` for local locking
-  * [PartitionSupervisor] Add `PartitionSupervisor.resize!/2` to resize the number of partitions in a supervisor (up to the limit it was started with)
-  * [Process] Handle arbitrarily high integer values in `Process.sleep/1`
-  * [Protocol] Add `@undefined_impl_description` to customize error message when an implementation is undefined
-  * [Protocol] Add `__deriving__/1` as optional macro callback to `Protocol`, no longer requiring empty implementations
-  * [String] Inspect special whitespace and zero-width characters using their Unicode representation
-  * [String] Update Unicode to 16.0
-
-#### ExUnit
-
-  * [ExUnit] Support parameterized tests on `ExUnit.Case`
-  * [ExUnit] Support test groups: tests in the same group never run concurrently
-  * [ExUnit.Case] Add `test_pid` as a tag
-
-#### IEx
-
-  * [IEx] Add `IEx.configure(auto_reload: true)` to automatically pick up modules recompiled from other operating system processes
-  * [IEx] Add `:dot_iex` support to `IEx.configure/1`
-  * [IEx] Add report for normal/shutdown exits in IEx
+  * [Kernel] Measure and optimize writing of `.beam` files in the compiler
+  * [Kernel] Optimize rare scenarios where type checking took too long
 
 #### Mix
 
-  * [mix compile] Ensure only a single operating system process can compile at a given time
-  * [mix deps.get] Ensure only a single operating system process can fetch deps at a given time
-  * [mix format] Add `mix format --migrate` to migrate from deprecated functionality
-  * [mix format] Add new options and metadata to improve formatting applying by editors and other environments
-  * [mix test] Taint failure manifest if requiring or compiling tests fail
-  * [Mix.Project] Add a `:listeners` configuration to listen to compilation events from the current and other operating system processes
-  * [Mix.Task.Compiler] Add API for fetching all persisted compiler diagnostics
-  * [Mix.Task.Compiler] Add API for fetching all compiler tasks
+  * [mix compile] Add flag `--no-check-cwd` to skip compiler check to aid debugging
 
 ### 2. Bug fixes
 
 #### Elixir
 
-  * [Code] Fix delimiter metadata for single quoted atoms and remote calls in `Code.string_to_quoted/2`
-  * [Code.Formatter] Fix formatter adding extra escapes to quoted remote calls
-  * [Code.Fragment] Properly handle keyword keys as their own entry
-  * [Inspect.Algebra] Ensure `next_break_fits` respects `line_length`
-  * [Kernel] Validate AST on `unquote` and `unquote_splicing` to provide better error reports instead of failing too late inside the compiler
-  * [Kernel] Avoid crashes when emitting diagnostics on code using \t for indentation
-  * [Module] Include module attribute line and name when tracing its aliases
-  * [Stream] Do not halt streams twice in `Stream.transform/5`
-  * [URI] Fix a bug when a schemaless URI is given to `URI.merge/2`
+  * [IO] Fix dialyzer warning on `IO.inspect :label`
+  * [Kernel] Ensure we warn on deprecated `~~~` unary operator
 
-#### ExUnit
+#### Logger
 
-  * [ExUnit.Assertions] Raise if guards are used in `assert/1` with `=`
-  * [ExUnit.Assertions] Format inserted/deleted maps in list assertions
-
-#### IEx
-
-  * [IEx.Helpers] `IEx.Helpers.recompile/0` will reload modules changed by other operating system processes
+  * [Logger] Reset ansi escapes before newlines in Logger
 
 #### Mix
 
-  * [mix compile] Ensure warnings from external resources are emitted with `--all-warnings` when files do not change
-  * [mix deps.compile] Fix escaping issues when invoking `rebar3` in some cases
-  * [mix escript] Fix escript layout and support storing `priv` directories
-  * [mix release] Make `.app` files deterministic in releases
-  * [Mix.Shell] Fix `Mix.Shell` on Windows when outputting non UTF-8 characters
+  * [mix compile] Warn if `elixirc_paths` is not a list of string paths
+  * [mix compile] Address regression where umbrella children were compiled too early and without respecting compilation flags
+  * [mix deps.compile] Improve reliability of `MIX_OS_DEPS_COMPILE_PARTITION_COUNT` across `mix escript.install`, `mix archive.install`, and others
+
+## v1.19.1 (2025-10-20)
+
+### 1. Bug fixes
+
+#### EEx
+
+  * [EEx] Address Dialyzer warnings when invoking `EEx.compile_string`
+
+#### Elixir
+
+  * [Kernel] Optimize how types are computed for pretty printing
+  * [Kernel] Optimize how differences are computed in the type system
+  * [Macro] Do not escape options given to `dbg/2`
+  * [Protocol] Improve protocol violation warnings
+
+#### Mix
+
+  * [mix compile] Do not attempt to touch deleted files when compilation fails and then resumed with missing files
+  * [mix deps.compile] Do not spawn partitions when all dependencies are local and already compiled
+
+## v1.19.0 (2025-10-16)
+
+### 1. Enhancements
+
+#### Elixir
+
+  * [Access] Add `Access.values/0` for traversing maps and keyword lists values
+  * [Base] Add functions to verify if an encoding is valid, such as `valid16?`, `valid64?`, and so forth
+  * [Calendar] Support 2-arity options for `Calendar.strftime/3` which receives the whole data type
+  * [Code] Add `:migrate_call_parens_on_pipe` formatter option
+  * [Code] Add `:indentation` option to `Code.string_to_quoted/2`
+  * [Code.Fragment] Preserve more block content around cursor in `container_cursor_to_quoted`
+  * [Code.Fragment] Add `:block_keyword_or_binary_operator` to `Code.Fragment` for more precise suggestions after operators and closing terminators
+  * [Code.Fragment] Add `Code.Fragment.lines/1`
+  * [Enum] Provide more information on `Enum.OutOfBoundsError`
+  * [Inspect] Allow `optional: :all` when deriving Inspect
+  * [Inspect.Algebra] Add optimistic/pessimistic groups as a simplified implementation of `next_break_fits`
+  * [IO.ANSI] Add ANSI codes to turn off conceal and crossed_out
+  * [Kernel] Raise when U+2028 and U+2029 characters are present in comments and strings to avoid line spoofing attacks
+  * [Kernel] Include the line for the previous clause in errors/warnings related to conflicts between defaults on function definitions
+  * [Kernel] Support `min/2` and `max/2` as guards
+  * [Kernel.ParallelCompiler] Add `each_long_verification_threshold` which invokes a callback when type checking a module takes too long
+  * [Kernel.ParallelCompiler] Include lines in `== Compilation error in file ... ==` slogans
+  * [Macro] Print debugging results from `Macro.dbg/3` as they happen, instead of once at the end
+  * [Macro] Add `__escape__/1` callback so structs can escape references and other runtime data types in `Macro.escape/1`
+  * [Module] Do not automatically load modules after their compilation, guaranteeing a more consistent compile time experience and drastically improving compilation times
+  * [OptionParser] Support the `:regex` type
+  * [OptionParser] Enhance parsing error to display available options
+  * [Protocol] Type checking of protocols dispatch and implementations
+  * [Regex] Add `Regex.to_embed/2` which returns an embeddable representation of regex in another regex
+  * [Regex] Raise error message when regexes are used as default values in struct fields for compatibility with Erlang/OTP 28
+  * [Registry] Add key-based partitioning of duplicate registries
+  * [String] Add `String.count/2` to count occurrences of a pattern
+  * [String] Update to Unicode 17.0.0
+
+#### ExUnit
+
+  * [ExUnit] Set a process label for each test
+  * [ExUnit.CaptureLog] Parallelize log dispatch when multiple processes are capturing log
+  * [ExUnit.Case] Add `:test_group` to the test context
+  * [ExUnit.Doctest] Support ellipsis in doctest exceptions to match the remaining of the exception
+  * [ExUnit.Doctest] Add `:inspect_opts` option for doctest
+
+#### IEx
+
+  * [IEx] Support multi-line prompts (due to this feature, `:continuation_prompt` and `:alive_continuation_prompt` are no longer supported as IEx configuration)
+  * [IEx.Autocomplete] Functions annotated with `@doc group: "Name"` metadata will appear within their own groups in autocompletion
+
+#### Logger
+
+  * [Logger] Accept any enumerable in `Logger.metadata/1`
+
+#### Mix
+
+  * [mix] Add support for `MIX_PROFILE_FLAGS` to configure `MIX_PROFILE`
+  * [mix compile] Debug the compiler and type checker PID when `MIX_DEBUG=1` and compilation/verification thresholds are met
+  * [mix compile] Add `Mix.Tasks.Compiler.reenable/1`
+  * [mix deps.compile] Support `MIX_OS_DEPS_COMPILE_PARTITION_COUNT` for compiling deps concurrently across multiple operating system processes
+  * [mix help] Add `mix help Mod`, `mix help :mod`, `mix help Mod.fun`, `mix help Mod.fun/arity`, and `mix help app:package`
+  * [mix format] Add options to mix format to allow excluding of files
+  * [mix test] Add `--name-pattern` option to `mix test`
+  * [mix test] Allow to distinguish the exit status between warnings as errors and test failures
+  * [mix xref graph] Add support for `--format json`
+  * [mix xref graph] Emit a warning if `--source` is part of a cycle
+  * [Mix] Support the `:compilers` option
+  * [Mix.Task.Compiler] Add `Mix.Task.Compiler.run/2`
+
+### 2. Bug fixes
+
+#### Elixir
+
+  * [Code] Return error on invalid unicode sequences in `Code.string_to_quoted/2` instead of raising
+  * [Code] Properly handle column annotation for `in` in `not in` expressions
+  * [DateTime] Do not truncate microseconds regardless of precision in `DateTime.diff/3`
+  * [Enum] Fix infinite loop on `Enum.take/2` with negative index on empty enumerable
+  * [File] Properly handle permissions errors cascading from parent in `File.mkdir_p/1`
+  * [Inspect] Inspect ill-formed structs as maps
+  * [Kernel] Properly increment metadata newline when `?` is followed by a literal newline character
+  * [Kernel] `not_a_map.key` now raises `BadMapError` for consistency with other map operations
+  * [Protocol] `defstruct/1` and `defexception/1` are now disabled inside `defprotocol` as to not allow defining structs/exceptions alongside a protocol
+  * [Regex] Fix `Regex.split/2` returning too many results when the chunk being split on was empty (which can happen when using features such as `/K`)
+  * [Stream] Ensure `Stream.transform/5` respects suspend command when its inner stream halts
+  * [URI] Several fixes to `URI.merge/2` related to trailing slashes, trailing dots, and hostless base URIs
+
+#### ExUnit
+
+  * [ExUnit.Assertions] Fix order of pinned variables in failure reports
+  * [ExUnit.Assertions] Raise if attempting to raise an assertion error with invalid message (not a binary)
+  * [ExUnit.Case] Do not crash on empty test unit groups
+
+#### IEx
+
+  * [IEx] Abort pipelines when there is an error in any step along the way
+
+#### Mix
+
+  * [mix cmd] Preserve argument quoting in subcommands by no longer performing shell expansion. To revert to the previous behaviour, pass `--shell` before the command name
+  * [mix compile] Fix bug where reverting changes to an external resource (such as HEEx template) after a compilation error would make it so the source module would not be compiled
+  * [mix compile] Avoid failures when locking compilation across different users
+  * [mix compile] Fix race condition when renaming files used by the compilation lock
+  * [mix format] Ensure the formatter does not go over the specified limit in certain corner cases
+  * [mix release] Fix `RELEASE_SYS_CONFIG` for Windows 11
+  * [mix test] Ensure modules are preloaded in `mix test --slowest-modules=N`
+  * [mix xref graph] Provide more consistent output by considering strong connected components when computing graphs. This means that, if you were using `mix xref graph --format cycles`, you will now get fewer but larger cycles, as cycle between `A` and `B` and another between `A` and `C` is now considered a single cycle between `A`, `B`, and `C`. Note the cycles themselves are not problematic, unless they have compile-time dependencies in them
 
 ### 3. Soft deprecations (no warnings emitted)
 
 #### Elixir
 
-  * [Inspect.Algebra] `color/3` is deprecated in favor of `color_doc/3`
-  * [Inspect.Algebra] `fold_doc/2` is deprecated in favor of `fold/2`
-  * [Kernel] Deprecate `unless` in favor of `if`. Use `mix format --migrate` to automate the migration
-  * [Macro] `Macro.struct!/2` is deprecated in favor of `Macro.struct_info!/2`
-  * [Protocol] Defining `__deriving__/3` inside the `Any` implementation is deprecated, derive it inside the protocol definition itself
-
-### 4. Hard deprecations
-
-#### EEx
-
-  * [EEx] `<%#` is deprecated in favor of `<%!--` or `<% #`
-  * [EEx] `c:EEx.handle_text/2` is deprecated in favor of `c:EEx.handle_text/3`
-
-#### Elixir
-
-  * [Code] Setting `:warnings_as_errors` is deprecated via `Code.put_compiler_option/2`. This must not affect developers, as the `:warnings_as_errors` option is managed by Mix tasks, and not directly used via the `Code` module
-  * [Enumerable] Deprecate returning a two-arity function in `Enumerable.slice/1`
-  * [List] `List.zip/1` is deprecated in favor of `Enum.zip/1`
-  * [Module] Deprecate `Module.eval_quoted/3` in favor of `Code.eval_quoted/3`
-  * [Range] Deprecate inferring negative ranges on `Range.new/2`
-  * [Tuple] `Tuple.append/2` is deprecated, use `Tuple.insert_at/3` instead
+  * [Inspect.Algebra] `next_break_fits` is deprecated in favor of `optimistic`/`pessimistic` groups
+  * [Node] `Node.start/2-3` is deprecated in favor of `Node.start/2` with a keyword list
 
 #### Mix
 
-  * [mix cmd] Deprecate `mix cmd --app APP` in favor of `mix do --app APP`
-  * [mix compile] `:warnings_as_errors` configuration in `:elixirc_options` is deprecated. Instead pass the `--warnings-as-errors` flag to `mix compile`. Alternatively, you might alias the task: `aliases: [compile: "compile --warnings-as-errors"]`
-  * [mix test] `:warnings_as_errors` configuration in `:test_elixirc_options` is deprecated. Instead pass the `--warnings-as-errors` flag to `mix test`. Alternatively, you might alias the task: `aliases: [test: "test --warnings-as-errors"]`
-  * [Mix.Tasks.Compile] Deprecate `compilers/0` in favor of `Mix.Task.Compiler.compilers/0`
+  * [mix compile] `--no-protocol-consolidation` is deprecated in favor of `--no-consolidate-protocols` for consistency with `mix.exs` configuration
+  * [mix compile.protocols] Protocol consolidation is now part of `compile.elixir` and the task itself has no effect
 
-## v1.17
+### 4. Hard deprecations
 
-The CHANGELOG for v1.17 releases can be found [in the v1.17 branch](https://github.com/elixir-lang/elixir/blob/v1.17/CHANGELOG.md).
+#### Elixir
+
+  * [Code] Warn if line-break characters outside of `\r` and `\r\n` are found in strings according to UX#55. This warning will be fast-tracked into an error for security reasons in Elixir v1.20, following a similar rule to bidirectional control characters. They will already raise if found in comments
+  * [Code] The `on_undefined_variable: :warn` is deprecated. Relying on undefined variables becoming function calls will not be supported in the future
+  * [File] Passing a callback as third argument to `File.cp/3` is deprecated, pass it as a `on_conflict: callback` option instead
+  * [File] Passing a callback as third argument to `File.cp_r/3` is deprecated, pass it as a `on_conflict: callback` option instead
+  * [Kernel] The struct update syntax, such as `%URI{uri | path: "/foo/bar"}`, now requires the given variable (or expression) to explicitly pattern match on the struct before it can be updated. This is because, thanks to the type system, pattern matching on structs can find more errors, more reliably, and we want to promote its usage. Once pattern matching is added, you may optionally convert the struct update syntax into the map update syntax `%{uri | path: "/foo/bar"}` with no less of typing guarantees
+  * [Kernel.ParallelCompiler] Passing `return_diagnostics: true` as an option is required on `compile`, `compile_to_path` and `require`
+
+#### Logger
+
+  * [Logger] The `:backends` configuration is deprecated, either set the `:default_handler` to false or start backends in your application start callback
+
+#### Mix
+
+  * [mix] The `:default_task`, `:preferred_cli_env`, and `:preferred_cli_target` configuration inside `def project` in your `mix.exs` has been deprecated in favor of `:default_task`, `:preferred_envs` and `:preferred_targets` inside the `def cli` function
+  * [mix do] Using commas as task separator in `mix do` (such as `mix do foo, bar`) is deprecated, use `+` instead (as in `mix do foo + bar`)
+
+## v1.18
+
+The CHANGELOG for v1.18 releases can be found [in the v1.18 branch](https://github.com/elixir-lang/elixir/blob/v1.18/CHANGELOG.md).

CODE_OF_CONDUCT.md

@@ -1,3 +1,9 @@
+<!--
+  SPDX-License-Identifier: Apache-2.0
+  SPDX-FileCopyrightText: 2021 The Elixir Team
+  SPDX-FileCopyrightText: 2012 Plataformatec
+-->
+
 # Code of Conduct
 
 Contact: elixir-lang-conduct@googlegroups.com

CONTRIBUTING.md

@@ -0,0 +1,197 @@
+<!--
+  SPDX-License-Identifier: Apache-2.0
+  SPDX-FileCopyrightText: 2021 The Elixir Team
+  SPDX-FileCopyrightText: 2012 Plataformatec
+-->
+
+# Contributing to Elixir
+
+We invite contributions to Elixir. To contribute, there are a few
+things you need to know about the code. First, Elixir code is divided
+by each application inside the `lib` folder:
+
+  * `elixir` - Elixir's kernel and standard library
+
+  * `eex` - EEx is the template engine that allows you to embed Elixir
+
+  * `ex_unit` - ExUnit is a simple test framework that ships with Elixir
+
+  * `iex` - IEx stands for Interactive Elixir: Elixir's interactive shell
+
+  * `logger` - Logger is the built-in logger
+
+  * `mix` - Mix is Elixir's build tool
+
+You can run all tests in the root directory with `make test`. You can
+also run tests for a specific framework with `make test_#{APPLICATION}`, for example,
+`make test_ex_unit`. If you just changed something in Elixir's standard
+library, you can run only that portion through `make test_stdlib`.
+
+If you are only changing one file, you can choose to compile and run tests
+for that specific file for faster development cycles. For example, if you
+are changing the String module, you can compile it and run its tests as:
+
+```sh
+bin/elixirc lib/elixir/lib/string.ex -o lib/elixir/ebin
+bin/elixir lib/elixir/test/elixir/string_test.exs
+```
+
+Some test files need their `test_helper.exs` to be explicitly required
+before, such as:
+
+```sh
+bin/elixir -r lib/logger/test/test_helper.exs lib/logger/test/logger_test.exs
+```
+
+You can also use the `LINE` env var to run a single test:
+
+```sh
+LINE=123 bin/elixir lib/elixir/test/elixir/string_test.exs
+````
+
+To recompile all (including Erlang modules):
+
+```sh
+make compile
+```
+
+After your changes are done, please remember to run `make format` to guarantee
+all files are properly formatted, then run the full suite with
+`make test`.
+
+If your contribution fails during the bootstrapping of the language,
+you can rebuild the language from scratch with:
+
+```sh
+make clean_elixir compile
+```
+
+Similarly, if you can not get Elixir to compile or the tests to pass after
+updating an existing checkout, run `make clean compile`. You can check
+[the official build status](https://github.com/elixir-lang/elixir/actions/workflows/ci.yml).
+More tasks can be found by reading the [Makefile](Makefile).
+
+We encourage contributors to write tests that capture both existing and newly
+introduced behavior, especially for bug fixes and major changes:
+
+  * **Bug Fixes:** If you are fixing a bug, please try to include a test that
+    *fails* before your change and *passes* afterward. This makes it easier to
+    confirm that the fix addresses the underlying issue and helps prevent
+    regressions in the future.
+  * **New Features or Major Changes:** If you are adding a new feature or making
+    major changes to existing functionality, please add tests that cover the
+    major parts of that functionality. Aim to have the best code coverage possible.
+
+With tests running and passing, you are ready to contribute to Elixir and
+[send a pull request](https://help.github.com/articles/using-pull-requests/).
+We have saved some excellent pull requests we have received in the past in
+case you are looking for some examples:
+
+  * [Implement Enum.member? - Pull request](https://github.com/elixir-lang/elixir/pull/992)
+  * [Add String.valid? - Pull request](https://github.com/elixir-lang/elixir/pull/1058)
+  * [Implement capture_io for ExUnit - Pull request](https://github.com/elixir-lang/elixir/pull/1059)
+
+## Reviewing changes
+
+Once a pull request is sent, the Elixir team will review your changes.
+We outline our process below to clarify the roles of everyone involved.
+
+All pull requests must be approved by two committers before being merged into
+the repository. If changes are necessary, the team will leave appropriate
+comments requesting changes to the code. Unfortunately, we cannot guarantee a
+pull request will be merged, even when modifications are requested, as the Elixir
+team will re-evaluate the contribution as it changes.
+
+Committers may also push style changes directly to your branch. If you would
+rather manage all changes yourself, you can disable the "Allow edits from maintainers"
+feature when submitting your pull request.
+
+The Elixir team may optionally assign someone to review a pull request.
+If someone is assigned, they must explicitly approve the code before
+another team member can merge it.
+
+When the review finishes, your pull request will be squashed and merged
+into the repository. If you have carefully organized your commits and
+believe they should be merged without squashing, please mention it in
+a comment.
+
+## Licensing and Compliance Requirements
+
+Please review our [Open Source Policy](OPEN_SOURCE_POLICY.md) for complete
+guidelines on licensing and compliance. Below is a summary of the key points
+affecting **all external contributors**:
+
+- Accepted Licenses: Any code contributed must be licensed under the
+  `Apache-2.0` license.
+- SPDX License Headers: With the exception of approved test fixture files,
+  all new or modified files in a pull request must include correct SPDX
+  headers. If you are creating a new file under the `Apache-2.0` license, for
+  instance, please use:
+    
+    ```elixir
+    # SPDX-License-Identifier: Apache-2.0
+    # SPDX-FileCopyrightText: 2021 The Elixir Team
+    ```
+    
+- No Executable Binaries: Contributions must **not** include any executable
+  binary files. If you require an exception (for example, certain test artifacts),
+  please see the policy on how to request approval and document exceptions.
+- Preserving Copyright and License Info: If you copy code from elsewhere,
+  ensure that **all original copyright and license notices remain intact**. If
+  they are missing or incomplete, you must add them.
+- Failure to Comply: Pull requests that do not meet these licensing and
+  compliance standards will be rejected or require modifications before merging.
+- Developer Certificate of Origin: All contributions are subject to the
+  Developer Certificate of Origin.
+
+    ```
+    By making a contribution to this project, I certify that:
+
+    (a) The contribution was created in whole or in part by me and I
+        have the right to submit it under the open source license
+        indicated in the file; or
+
+    (b) The contribution is based upon previous work that, to the 
+        best of my knowledge, is covered under an appropriate open 
+        source license and I have the right under that license to   
+        submit that work with modifications, whether created in whole
+        or in part by me, under the same open source license (unless
+        I am permitted to submit under a different license), as 
+        Indicated in the file; or
+
+    (c) The contribution was provided directly to me by some other
+        person who certified (a), (b) or (c) and I have not modified
+        it.
+
+    (d) I understand and agree that this project and the contribution
+        are public and that a record of the contribution (including 
+        all personal information I submit with it, including my
+        sign-off) is maintained indefinitely and may be redistributed
+        consistent with this project or the open source license(s)
+        involved.
+    ```
+
+    See http://developercertificate.org/ for a copy of the Developer Certificate
+    of Origin license.
+
+## Building documentation
+
+Building the documentation requires that [ExDoc](https://github.com/elixir-lang/ex_doc)
+is installed and built alongside Elixir:
+
+```sh
+# After cloning and compiling Elixir, in its parent directory:
+git clone https://github.com/elixir-lang/ex_doc.git
+cd ex_doc && ../elixir/bin/elixir ../elixir/bin/mix do deps.get + compile
+```
+
+Now go back to Elixir's root directory and run:
+
+```sh
+make docs                  # to generate HTML pages
+make docs DOCS_FORMAT=epub # to generate EPUB documents
+```
+
+This will produce documentation sets for `elixir`, `eex`, `ex_unit`, `iex`, `logger`,
+and `mix` under the `doc` directory. If you are planning to contribute documentation,
+[please check our best practices for writing documentation](https://hexdocs.pm/elixir/writing-documentation.html).

LICENSES/Apache-2.0.txt

@@ -0,0 +1,73 @@
+Apache License
+Version 2.0, January 2004
+http://www.apache.org/licenses/
+
+TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+1. Definitions.
+
+"License" shall mean the terms and conditions for use, reproduction, and distribution as defined by Sections 1 through 9 of this document.
+
+"Licensor" shall mean the copyright owner or entity authorized by the copyright owner that is granting the License.
+
+"Legal Entity" shall mean the union of the acting entity and all other entities that control, are controlled by, or are under common control with that entity. For the purposes of this definition, "control" means (i) the power, direct or indirect, to cause the direction or management of such entity, whether by contract or otherwise, or (ii) ownership of fifty percent (50%) or more of the outstanding shares, or (iii) beneficial ownership of such entity.
+
+"You" (or "Your") shall mean an individual or Legal Entity exercising permissions granted by this License.
+
+"Source" form shall mean the preferred form for making modifications, including but not limited to software source code, documentation source, and configuration files.
+
+"Object" form shall mean any form resulting from mechanical transformation or translation of a Source form, including but not limited to compiled object code, generated documentation, and conversions to other media types.
+
+"Work" shall mean the work of authorship, whether in Source or Object form, made available under the License, as indicated by a copyright notice that is included in or attached to the work (an example is provided in the Appendix below).
+
+"Derivative Works" shall mean any work, whether in Source or Object form, that is based on (or derived from) the Work and for which the editorial revisions, annotations, elaborations, or other modifications represent, as a whole, an original work of authorship. For the purposes of this License, Derivative Works shall not include works that remain separable from, or merely link (or bind by name) to the interfaces of, the Work and Derivative Works thereof.
+
+"Contribution" shall mean any work of authorship, including the original version of the Work and any modifications or additions to that Work or Derivative Works thereof, that is intentionally submitted to Licensor for inclusion in the Work by the copyright owner or by an individual or Legal Entity authorized to submit on behalf of the copyright owner. For the purposes of this definition, "submitted" means any form of electronic, verbal, or written communication sent to the Licensor or its representatives, including but not limited to communication on electronic mailing lists, source code control systems, and issue tracking systems that are managed by, or on behalf of, the Licensor for the purpose of discussing and improving the Work, but excluding communication that is conspicuously marked or otherwise designated in writing by the copyright owner as "Not a Contribution."
+
+"Contributor" shall mean Licensor and any individual or Legal Entity on behalf of whom a Contribution has been received by Licensor and subsequently incorporated within the Work.
+
+2. Grant of Copyright License. Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare Derivative Works of, publicly display, publicly perform, sublicense, and distribute the Work and such Derivative Works in Source or Object form.
+
+3. Grant of Patent License. Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable (except as stated in this section) patent license to make, have made, use, offer to sell, sell, import, and otherwise transfer the Work, where such license applies only to those patent claims licensable by such Contributor that are necessarily infringed by their Contribution(s) alone or by combination of their Contribution(s) with the Work to which such Contribution(s) was submitted. If You institute patent litigation against any entity (including a cross-claim or counterclaim in a lawsuit) alleging that the Work or a Contribution incorporated within the Work constitutes direct or contributory patent infringement, then any patent licenses granted to You under this License for that Work shall terminate as of the date such litigation is filed.
+
+4. Redistribution. You may reproduce and distribute copies of the Work or Derivative Works thereof in any medium, with or without modifications, and in Source or Object form, provided that You meet the following conditions:
+
+     (a) You must give any other recipients of the Work or Derivative Works a copy of this License; and
+
+     (b) You must cause any modified files to carry prominent notices stating that You changed the files; and
+
+     (c) You must retain, in the Source form of any Derivative Works that You distribute, all copyright, patent, trademark, and attribution notices from the Source form of the Work, excluding those notices that do not pertain to any part of the Derivative Works; and
+
+     (d) If the Work includes a "NOTICE" text file as part of its distribution, then any Derivative Works that You distribute must include a readable copy of the attribution notices contained within such NOTICE file, excluding those notices that do not pertain to any part of the Derivative Works, in at least one of the following places: within a NOTICE text file distributed as part of the Derivative Works; within the Source form or documentation, if provided along with the Derivative Works; or, within a display generated by the Derivative Works, if and wherever such third-party notices normally appear. The contents of the NOTICE file are for informational purposes only and do not modify the License. You may add Your own attribution notices within Derivative Works that You distribute, alongside or as an addendum to the NOTICE text from the Work, provided that such additional attribution notices cannot be construed as modifying the License.
+
+     You may add Your own copyright statement to Your modifications and may provide additional or different license terms and conditions for use, reproduction, or distribution of Your modifications, or for any such Derivative Works as a whole, provided Your use, reproduction, and distribution of the Work otherwise complies with the conditions stated in this License.
+
+5. Submission of Contributions. Unless You explicitly state otherwise, any Contribution intentionally submitted for inclusion in the Work by You to the Licensor shall be under the terms and conditions of this License, without any additional terms or conditions. Notwithstanding the above, nothing herein shall supersede or modify the terms of any separate license agreement you may have executed with Licensor regarding such Contributions.
+
+6. Trademarks. This License does not grant permission to use the trade names, trademarks, service marks, or product names of the Licensor, except as required for reasonable and customary use in describing the origin of the Work and reproducing the content of the NOTICE file.
+
+7. Disclaimer of Warranty. Unless required by applicable law or agreed to in writing, Licensor provides the Work (and each Contributor provides its Contributions) on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. You are solely responsible for determining the appropriateness of using or redistributing the Work and assume any risks associated with Your exercise of permissions under this License.
+
+8. Limitation of Liability. In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall any Contributor be liable to You for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising as a result of this License or out of the use or inability to use the Work (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if such Contributor has been advised of the possibility of such damages.
+
+9. Accepting Warranty or Additional Liability. While redistributing the Work or Derivative Works thereof, You may choose to offer, and charge a fee for, acceptance of support, warranty, indemnity, or other liability obligations and/or rights consistent with this License. However, in accepting such obligations, You may act only on Your own behalf and on Your sole responsibility, not on behalf of any other Contributor, and only if You agree to indemnify, defend, and hold each Contributor harmless for any liability incurred by, or claims asserted against, such Contributor by reason of your accepting any such warranty or additional liability.
+
+END OF TERMS AND CONDITIONS
+
+APPENDIX: How to apply the Apache License to your work.
+
+To apply the Apache License to your work, attach the following boilerplate notice, with the fields enclosed by brackets "[]" replaced with your own identifying information. (Don't include the brackets!)  The text should be enclosed in the appropriate comment syntax for the file format. We also recommend that a file or class name and description of purpose be included on the same "printed page" as the copyright notice for easier identification within third-party archives.
+
+Copyright [yyyy] [name of copyright owner]
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.

LICENSES/LicenseRef-elixir-trademark-policy.txt

@@ -0,0 +1,98 @@
+ELIXIR TEAM TRADEMARKS POLICY
+
+This document outlines the policy for allowed usage of the “Elixir” word and the
+Elixir logo by other parties.
+
+“Elixir” and the Elixir logo are registered trademarks of the Elixir Team. The
+Elixir Team believes in a decentralized approach to growing the community and
+the ecosystem, independent of the Elixir project and the Elixir Team.
+
+Anyone can use the Elixir trademarks if that use of the trademark is nominative.
+The trademarks must not be used to disparage the project and its community, nor
+be used in any way to imply ownership, endorsement, or association with the
+Elixir project and the Elixir Team.
+
+You must not visually combine the Elixir logo with any other images, or change
+the logo in any way other than ways required by printing restrictions. If you
+want to create your own visual identity in relation to Elixir, you might use the
+shape of an unrelated “water drop” as part of your design, as seen in many
+community projects and initiatives. You must not combine or modify the Elixir
+logo.
+
+The Elixir logo is available in our repository in both vertical and horizontal
+versions.
+
+Nominative use
+The “nominative use” (or “nominative fair use”) is a legal doctrine that
+authorizes everyone (even commercial companies) to use or refer to the trademark
+of another if:
+
+The product or service in question must be one not readily identifiable without
+use of the trademark.
+
+Only so much of the mark or marks may be used as is reasonably necessary to
+identify the product or service.
+
+The organization using the mark must do nothing that would, in conjunction with
+the mark, suggest sponsorship or endorsement by the trademark holder.
+
+Our trademarks must be used to refer to the Elixir programming language.
+
+Examples of permitted use
+All examples listed next must strictly adhere to the terms outlined in the
+previous sections:
+
+Usage of the Elixir logo to say a technology is “powered by Elixir” under
+nominative use. Linking back to the Elixir website, if possible, is appreciated.
+
+Usage of the Elixir logo to display it as a supported technology in a service or
+platform. For instance, you may say “we support Elixir” and use the Elixir logo,
+but you may not refer to yourself as “the Elixir platform” nor imply any form of
+endorsement or association with Elixir.
+
+Usage of the Elixir logo in non-commercial community meetups, in presentations,
+and in courses when referring to the language and its ecosystem under nominative
+use.
+
+Usage of the Elixir logo in non-commercial swag (stickers, t-shirts, mugs, etc)
+to promote the Elixir programming language. The Elixir marks must be the only
+marks featured in the product. You need permission to make swag that include
+Elixir and other third party marks in them.
+
+Inclusion of the Elixir logo in non-commercial icon sets. Use of the Elixir
+icons must still adhere to Elixir’s trademark policies.
+
+Usage of the “Elixir” word in book titles, meetups, conferences, and podcasts.
+You must not use the word to imply uniqueness or endorsement from the Elixir
+team. “The Elixir book” and “The Elixir podcast” are not permitted.
+“Elixir in Action”, “Thinking Elixir”, and “Kraków Elixir User Group” are valid
+examples already in use today.
+
+Usage of the “Elixir” word in the names of freely distributed software and
+hardware products is allowed when referring to use with or suitability for the
+Elixir programming language, such as wxElixir, Elixirsense, etc. If the product
+includes the Elixir programming language itself, then you must also respect its
+license.
+
+Examples of not permitted use
+Here is a non-exhaustive list of non permitted uses of the marks:
+
+Usage of the Elixir logo in book covers, conferences, and podcasts.
+
+Usage of the Elixir logo as the mark of third party projects, even in combination
+with other marks.
+
+Naming any company or product after Elixir, such as “The Elixir Hosting”,
+“The Elixir Consultants”, etc.
+
+Examples that require permission
+Here are some examples that may be granted permission upon request:
+
+Selling merchandise (stickers, t-shirts, mugs, etc).
+You can request permission by emailing trademarks@elixir-lang.org.
+
+Important note
+Nothing in this page shall be interpreted to allow any third party to claim any
+association with the Elixir project and the Elixir Team, or to imply any
+approval or support by the Elixir project and the Elixir Team for any third
+party products, services, or events.

LICENSES/LicenseRef-scancode-unicode.txt

@@ -0,0 +1,58 @@
+UNICODE, INC. LICENSE AGREEMENT - DATA FILES AND SOFTWARE
+
+Unicode Data Files include all data files under the directories
+http://www.unicode.org/Public/, http://www.unicode.org/reports/, and
+http://www.unicode.org/cldr/data/ . Unicode Software includes any source
+code published in the Unicode Standard or under the directories
+http://www.unicode.org/Public/, http://www.unicode.org/reports/, and
+http://www.unicode.org/cldr/data/.
+
+NOTICE TO USER: Carefully read the following legal agreement. BY
+DOWNLOADING, INSTALLING, COPYING OR OTHERWISE USING UNICODE INC.'S DATA
+FILES ("DATA FILES"), AND/OR SOFTWARE ("SOFTWARE"), YOU UNEQUIVOCALLY
+ACCEPT, AND AGREE TO BE BOUND BY, ALL OF THE TERMS AND CONDITIONS OF THIS
+AGREEMENT. IF YOU DO NOT AGREE, DO NOT DOWNLOAD, INSTALL, COPY, DISTRIBUTE
+OR USE THE DATA FILES OR SOFTWARE.
+
+COPYRIGHT AND PERMISSION NOTICE
+
+Copyright ©  Unicode, Inc. All rights reserved. Distributed under
+the Terms of Use in http://www.unicode.org/copyright.html.
+
+Permission is hereby granted, free of charge, to any person obtaining a
+copy of the Unicode data files and any associated documentation (the
+"Data Files") or Unicode software and any associated documentation (the
+"Software") to deal in the Data Files or Software without restriction,
+including without limitation the rights to use, copy, modify, merge,
+publish, distribute, and/or sell copies of the Data Files or Software,
+and to permit persons to whom the Data Files or Software are furnished
+to do so, provided that
+
+(a) the above copyright notice(s) and this permission notice appear with
+all copies of the Data Files or Software,
+
+(b) both the above copyright notice(s) and this permission notice appear
+in associated documentation, and
+
+(c) there is clear notice in each modified Data File or in the Software
+as well as in the documentation associated with the Data File(s) or
+Software that the data or software has been modified.
+
+THE DATA FILES AND SOFTWARE ARE PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
+WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE COPYRIGHT
+HOLDER OR HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM, OR
+ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER
+RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
+CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+CONNECTION WITH THE USE OR PERFORMANCE OF THE DATA FILES OR SOFTWARE.
+
+Except as contained in this notice, the name of a copyright holder shall
+not be used in advertising or otherwise to promote the sale, use or
+other dealings in these Data Files or Software without prior written
+authorization of the copyright holder.
+
+Unicode and the Unicode logo are trademarks of Unicode, Inc., and may be
+registered in some jurisdictions. All other trademarks and registered
+trademarks mentioned herein are the property of their respective owners.

Makefile

@@ -1,9 +1,14 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 PREFIX ?= /usr/local
 TEST_FILES ?= "*_test.exs"
 SHARE_PREFIX ?= $(PREFIX)/share
 MAN_PREFIX ?= $(SHARE_PREFIX)/man
 # CANONICAL := main/
 ELIXIRC := bin/elixirc --ignore-module-conflict $(ELIXIRC_OPTS)
+ELIXIRC_MIN_SIG := $(ELIXIRC) -e 'Code.put_compiler_option :infer_signatures, []'
 ERLC := erlc -I lib/elixir/include
 ERL_MAKE := erl -make
 ERL := erl -I lib/elixir/include -noshell -pa lib/elixir/ebin
@@ -21,15 +26,15 @@ GIT_TAG = $(strip $(shell head="$(call GIT_REVISION)"; git tag --points-at $$hea
 SOURCE_DATE_EPOCH_PATH = lib/elixir/tmp/ebin_reproducible
 SOURCE_DATE_EPOCH_FILE = $(SOURCE_DATE_EPOCH_PATH)/SOURCE_DATE_EPOCH
 
-.PHONY: install install_man build_plt clean_plt dialyze test check_reproducible clean clean_elixir clean_man format docs Docs.zip Precompiled.zip zips
+.PHONY: cover install install_man build_plt clean_plt dialyze test check_reproducible clean clean_elixir clean_man format docs Docs.zip Precompiled.zip zips
 .NOTPARALLEL:
 
 #==> Functions
 
 define CHECK_ERLANG_RELEASE
-	erl -noshell -eval '{V,_} = string:to_integer(erlang:system_info(otp_release)), io:fwrite("~s", [is_integer(V) and (V >= 25)])' -s erlang halt | grep -q '^true'; \
+	erl -noshell -eval '{V,_} = string:to_integer(erlang:system_info(otp_release)), io:fwrite("~s", [is_integer(V) and (V >= 26)])' -s erlang halt | grep -q '^true'; \
 		if [ $$? != 0 ]; then \
-		  echo "At least Erlang/OTP 25.0 is required to build Elixir"; \
+		  echo "At least Erlang/OTP 26.0 is required to build Elixir"; \
 		  exit 1; \
 		fi
 endef
@@ -48,6 +53,10 @@ lib/$(1)/ebin/Elixir.$(2).beam: $(wildcard lib/$(1)/lib/*.ex) $(wildcard lib/$(1
 test_$(1): test_formatted $(1)
 	@ echo "==> $(1) (ex_unit)"
 	$(Q) cd lib/$(1) && ../../bin/elixir -r "test/test_helper.exs" -pr "test/**/$(TEST_FILES)";
+
+cover/ex_unit_$(1).coverdata:
+	$(Q) COVER="1" $(MAKE) test_$(1)
+cover/combined.coverdata: cover/ex_unit_$(1).coverdata
 endef
 
 define WRITE_SOURCE_DATE_EPOCH
@@ -97,7 +106,7 @@ $(KERNEL): lib/elixir/src/* lib/elixir/lib/*.ex lib/elixir/lib/*/*.ex lib/elixir
 		"$(MAKE)" unicode; \
 	fi
 	@ echo "==> elixir (compile)";
-	$(Q) cd lib/elixir && ../../$(ELIXIRC) "lib/**/*.ex" -o ebin;
+	$(Q) cd lib/elixir && ../../$(ELIXIRC_MIN_SIG) "lib/**/*.ex" -o ebin;
 
 $(APP): lib/elixir/src/elixir.app.src lib/elixir/ebin VERSION $(GENERATE_APP)
 	$(Q) $(GENERATE_APP) $(VERSION)
@@ -105,9 +114,9 @@ $(APP): lib/elixir/src/elixir.app.src lib/elixir/ebin VERSION $(GENERATE_APP)
 unicode: $(UNICODE)
 $(UNICODE): lib/elixir/unicode/*
 	@ echo "==> unicode (compile)";
-	$(Q) $(ELIXIRC) lib/elixir/unicode/unicode.ex -o lib/elixir/ebin;
-	$(Q) $(ELIXIRC) lib/elixir/unicode/tokenizer.ex -o lib/elixir/ebin;
-	$(Q) $(ELIXIRC) lib/elixir/unicode/security.ex -o lib/elixir/ebin;
+	$(Q) $(ELIXIRC_MIN_SIG) lib/elixir/unicode/unicode.ex -o lib/elixir/ebin;
+	$(Q) $(ELIXIRC_MIN_SIG) lib/elixir/unicode/tokenizer.ex -o lib/elixir/ebin;
+	$(Q) $(ELIXIRC_MIN_SIG) lib/elixir/unicode/security.ex -o lib/elixir/ebin;
 
 $(eval $(call APP_TEMPLATE,ex_unit,ExUnit))
 $(eval $(call APP_TEMPLATE,logger,Logger))
@@ -170,6 +179,7 @@ clean: clean_man
 	rm -rf lib/mix/test/fixtures/git_sparse_repo/
 	rm -rf lib/mix/test/fixtures/archive/ebin/
 	rm -f erl_crash.dump
+	rm -rf cover
 
 clean_elixir:
 	$(Q) rm -f lib/*/ebin/Elixir.*.beam
@@ -177,7 +187,7 @@ clean_elixir:
 #==> Documentation tasks
 
 SOURCE_REF = $(shell tag="$(call GIT_TAG)" revision="$(call GIT_REVISION)"; echo "$${tag:-$$revision}")
-DOCS_COMPILE = CANONICAL=$(CANONICAL) bin/elixir ../ex_doc/bin/ex_doc "$(1)" "$(VERSION)" "lib/$(2)/ebin" --main "$(3)" --source-url "https://github.com/elixir-lang/elixir" --source-ref "$(call SOURCE_REF)" --logo lib/elixir/pages/images/logo.png --output doc/$(2) --canonical "https://hexdocs.pm/$(2)/$(CANONICAL)" --homepage-url "https://elixir-lang.org/docs.html" $(4)
+DOCS_COMPILE = CANONICAL=$(CANONICAL) bin/elixir ../ex_doc/bin/ex_doc "$(1)" "$(VERSION)" "lib/$(2)/ebin" --main "$(3)" --source-url "https://github.com/elixir-lang/elixir" --source-ref "$(call SOURCE_REF)" --logo lib/elixir/pages/images/logo.png --output doc/$(2) --canonical "https://hexdocs.pm/$(2)/$(CANONICAL)" --homepage-url "https://elixir-lang.org/docs.html" $(DOCS_OPTIONS) $(4)
 DOCS_CONFIG = bin/elixir lib/elixir/scripts/docs_config.exs "$(1)"
 
 docs: compile ../ex_doc/bin/ex_doc docs_elixir docs_eex docs_mix docs_iex docs_ex_unit docs_logger
@@ -219,19 +229,19 @@ docs_logger: compile ../ex_doc/bin/ex_doc
 	$(call DOCS_CONFIG,logger)
 
 ../ex_doc/bin/ex_doc:
-	@ echo "ex_doc is not found in ../ex_doc as expected. See README for more information."
+	@ echo "ex_doc is not found in ../ex_doc as expected. See CONTRIBUTING.md for more information."
 	@ false
 
 #==> Zip tasks
 
 Docs.zip: docs
 	rm -f Docs.zip
-	zip -9 -r Docs.zip CHANGELOG.md doc NOTICE LICENSE README.md
+	zip -9 -r Docs.zip CHANGELOG.md doc LICENSE README.md
 	@ echo "Docs file created $(CURDIR)/Docs.zip"
 
 Precompiled.zip: build_man compile
 	rm -f Precompiled.zip
-	zip -9 -r Precompiled.zip bin CHANGELOG.md lib/*/ebin lib/*/lib LICENSE Makefile man NOTICE README.md VERSION
+	zip -9 -r Precompiled.zip bin CHANGELOG.md lib/*/ebin lib/*/lib LICENSE Makefile man README.md VERSION
 	@ echo "Precompiled file created $(CURDIR)/Precompiled.zip"
 
 #==> Test tasks
@@ -282,6 +292,15 @@ test_stdlib: compile
 		cd lib/elixir && ../../bin/elixir --sname primary -r "test/elixir/test_helper.exs" -pr "test/elixir/**/$(TEST_FILES)"; \
 	fi
 
+cover/ex_unit_elixir.coverdata:
+	$(Q) COVER="1" $(MAKE) test_stdlib
+cover/combined.coverdata: cover/ex_unit_elixir.coverdata
+
+cover/combined.coverdata:
+	bin/elixir ./lib/elixir/scripts/cover.exs
+
+cover: cover/combined.coverdata
+
 #==> Dialyzer tasks
 
 DIALYZER_OPTS = --no_check_plt --fullpath -Werror_handling -Wunmatched_returns -Wunderspecs

NOTICE

@@ -1,38 +0,0 @@
-LEGAL NOTICE INFORMATION
-------------------------
-
-All the files in this distribution are copyright to the terms below.
-
-== lib/elixir/src/elixir_json.erl
-== lib/elixir/src/elixir_parser.erl (generated by build scripts)
-
-Copyright Ericsson AB 1996-2024
-
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
-
-    https://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
-
-== All other files
-
-Copyright 2012 Plataformatec
-Copyright 2021 The Elixir Team
-
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
-
-   https://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.

OPEN_SOURCE_POLICY.md

@@ -0,0 +1,168 @@
+<!--
+  SPDX-License-Identifier: Apache-2.0
+  SPDX-FileCopyrightText: 2021 The Elixir Team
+-->
+
+# Open Source Policy
+
+## 1. Introduction
+
+This Open Source Policy outlines the licensing, contribution, and compliance
+requirements for all code released under the Elixir project. By adhering to
+these guidelines, we ensure that our community, maintainers, and contributors
+uphold both legal and ethical standards while fostering a collaborative,
+transparent environment.
+
+This policy exists to support and protect the Elixir community. It aims to
+balance openness, collaboration, and respect for all contributors’ rights,
+ensuring that Elixir remains a trusted and innovative open source project.
+
+## 2. Scope
+
+This policy applies to the Elixir Programming language, located at
+https://github.com/elixir-lang/elixir. It covers every file, and contribution
+made, including documentation and any associated assets.
+
+## 3. Licensing
+
+All code released by the Elixir team is licensed under the
+[Apache-2.0](./LICENSES/Apache-2.0.txt) license. Additionally, the following
+licenses are recognized as permissible in this project:
+
+- The Unicode license, as documented at
+  [LicenseRef-scancode-unicode](./LICENSES/LicenseRef-scancode-unicode.txt)
+- The Elixir Trademark Policy, as documented at
+  [LicenseRef-elixir-trademark-policy](./LICENSES/LicenseRef-elixir-trademark-policy.txt)
+
+These licenses are considered acceptable for any files or code that form part of
+an Elixir repository. If a contribution requires a different license, it must
+either be rejected or prompt an update to this policy.
+
+## 4. Contributing to Elixir Projects
+
+Any code contributed to Elixir repositories must fall under one of the accepted
+licenses (Apache-2.0, Unicode, or Elixir Trademark). Contributions under any
+other license will be rejected unless this policy is formally revised to include
+that license. All files except those specifically exempted (e.g., certain test
+fixture files) must contain SPDX license and copyright headers
+(`SPDX-License-Identifier` and `SPDX-FileCopyrightText`). If a file qualifies
+for an exception, this must be configured in the ORT (Open Source Review Toolkit)
+configuration and undergo review.
+
+Contributions must not introduce executable binary files into the codebase.
+
+Every Elixir project within the organization will have an automated GitHub
+Action to enforce these rules. This mechanism aids in detecting non-compliant
+licenses or files early in the review process.
+
+## 5. Preservation of Copyright and License Information
+
+Any third-party code incorporated into Elixir projects must retain original
+copyright and license headers. If no such headers exist in the source, they must
+be added. This practice ensures that original authors receive proper credit and
+that the licensing lineage is preserved.
+
+## 6. Objectives
+
+The Elixir project aims to promote a culture of responsible open source usage.
+Specifically, our objectives include:
+
+### 6.1 Clearly Define and Communicate Licensing & Compliance Policies
+
+We will identify and document all third-party dependencies, ensure that license
+information is communicated clearly, and maintain a project-wide license policy
+or compliance handbook.
+
+### 6.2 Implement Clear Processes for Reviewing Contributions
+
+We will provide well-defined contribution guidelines. We implement the
+Developer Certificate of Origin (DCO) for additional clarity regarding
+contributor rights and obligations.
+
+### 6.3 Track and Audit Third-Party Code Usage
+
+All projects will implement a Software Bill of Materials (SBoM) strategy and
+regularly verify license compliance for direct and transitive dependencies.
+
+### 6.4 Monitor and Continuously Improve Open Source Compliance
+
+We will conduct periodic internal audits, integrate compliance checks into
+continuous integration (CI/CD) pipelines, and regularly review and refine these
+objectives to align with best practices.
+
+## 7. Roles and Responsibilities
+
+### 7.1 Core Team Member
+
+Core Team Members are responsible for being familiar with this policy and
+ensuring it is consistently enforced. They must demonstrate sufficient
+competencies to understand the policy requirements and must reject or request
+changes to any pull requests that violate these standards.
+
+### 7.2 Contributor
+
+Contributors are expected to follow this policy when submitting code. If a
+contributor submits a pull request that does not comply with the policy
+(e.g., introduces a disallowed license), Core Team Members have the authority to
+reject it or request changes. No special competencies are required for
+contributors beyond awareness and adherence to the policy.
+
+### 7.3 EEF CISO
+
+The CISO designated by the Erlang Ecosystem Foundation (EEF) provides oversight
+on queries and guidance regarding open source compliance or legal matters for
+Elixir. The CISO is responsible for checking ongoing compliance with the policy,
+escalating potential violations to the Core Team, and involving legal counsel if
+necessary. This role does not require legal expertise but does involve
+initiating legal or community discussions when needed.
+
+## 8. Implications of Failing to Follow the Program Requirements
+
+If a violation of this policy is identified, the Elixir Core Team will undertake
+the following actions:
+
+## 8.1 Review the Codebase for Additional Violations
+
+We will investigate the codebase thoroughly to detect any similar instances of
+non-compliance.
+
+## 8.2 Review and Update the Process or Policy
+
+In collaboration with the EEF CISO, the Elixir Core Team will assess the policy
+and our internal workflows, making any necessary clarifications or amendments to
+reduce the likelihood of recurrence.
+
+## 8.3 Notify and Train Core Team Members
+
+We will ensure that all active Core Team Members are informed about any policy
+changes and understand how to apply them in everyday development.
+
+## 8.4 Remove or Replace the Offending Code
+
+If required, we will remove or replace the non-compliant code.
+
+## 9. Contact
+
+The project maintains a private mailing list at
+[policy@elixir-lang.org](mailto:policy@elixir-lang.org) for handling licensing
+and policy-related queries. Email is the preferred communication channel, and
+the EEF CISO will be included on this list to provide assistance and ensure
+timely responses. While solutions may take longer to implement, the project
+commits to acknowledging all queries within five business days.
+
+## 10. External Contributions of Core Team Members
+
+When Core Team Members contribute to repositories outside Elixir, they do so in
+a personal capacity or via their employer. They will not act as official
+representatives of the Elixir team in those external contexts.
+
+## 11. Policy Review and Amendments
+
+This policy will be revisited annually to address new concerns, accommodate
+changes in community standards, or adjust to emerging legal or technical
+requirements. Proposed amendments must be reviewed by the Core Team and, if
+necessary, by the EEF CISO. Any significant changes will be communicated to
+contributors and made publicly available.
+
+*Effective Date: 2025-02-20*  
+*Last Reviewed: 2025-02-20*

README.md

@@ -1,3 +1,9 @@
+<!--
+  SPDX-License-Identifier: Apache-2.0
+  SPDX-FileCopyrightText: 2021 The Elixir Team
+  SPDX-FileCopyrightText: 2012 Plataformatec
+-->
+
 <h1>
  <picture>
   <source media="(prefers-color-scheme: dark)" srcset="https://github.com/elixir-lang/elixir-lang.github.com/raw/main/images/logo/logo-dark.png">
@@ -6,6 +12,7 @@
 </h1>
 
 [![CI](https://github.com/elixir-lang/elixir/actions/workflows/ci.yml/badge.svg?branch=main)](https://github.com/elixir-lang/elixir/actions/workflows/ci.yml?query=branch%3Amain)
+[![OpenSSF Best Practices](https://www.bestpractices.dev/projects/10187/badge)](https://www.bestpractices.dev/projects/10187)
 
 Elixir is a dynamic, functional language designed for building scalable
 and maintainable applications.
@@ -25,19 +32,18 @@ information, please read our [Security Policy][9].
 All interactions in our official communication channels follow our
 [Code of Conduct][1].
 
+All contributions are required to conform to our [Open Source Policy][11].
+
 ## Bug reports
 
 For reporting bugs, [visit our issue tracker][2] and follow the steps
 for reporting a new issue. **Please disclose security vulnerabilities
-privately at <elixir-security@googlegroups.com>**.
+privately [in our Security page](https://github.com/elixir-lang/elixir/security)**.
 
-## Issues tracker management
-
-All currently open bugs related to the Elixir repository are listed
-in the issues tracker. The Elixir team uses the issues tracker to focus
-on *actionable items*, including planned enhancements in the short and
-medium term. We also do our best to label entries for clarity and to ease
-collaboration.
+All currently open bugs related to Elixir are listed in the issues tracker.
+The Elixir team uses the issues tracker to focus on *actionable items*,
+including planned enhancements in the short and medium term. We also do
+our best to label entries for clarity and to ease collaboration.
 
 Our *actionable item policy* has some important consequences, such as:
 
@@ -49,38 +55,42 @@ Our *actionable item policy* has some important consequences, such as:
     elsewhere if appropriate).
 
   * We actively close unrelated and non-actionable issues to keep the
-    issues tracker tidy. We may get things wrong from time to
-    time and will gladly revisit issues, reopening when necessary.
+    issues tracker tidy. If you believe we got something wrong, drop a
+    comment and we can always reopen the issue.
 
-Keep the tone positive and be kind! For more information, see the
-[Code of Conduct][1].
+By keeping the overall issues tracker tidy and organized, the community
+can easily peak at what is coming in new releases and also get involved
+by commenting on existing issues and submitting pull requests. Please
+remember to keep the tone positive and be kind! For more information,
+see the [Code of Conduct][1].
 
-### Proposing new features
-
-For proposing new features, please start a discussion in the
-[Elixir Core mailing list][3]. The [language development history and
-its focus are described on our website](https://elixir-lang.org/development.html).
-
-Keep in mind that it is your responsibility to argue and explain
-why a feature is useful and how it will impact the codebase and
-the community. A good proposal includes the problem description
-and how the proposed solution compares with existing alternatives
-in the Elixir ecosystem (as well as in other languages). To iron
-out a proposal before submission, consider using and gathering
-feedback from the community spaces [listed on the sidebar of the
-Elixir website](https://elixir-lang.org/).
-
-Once a proposal is accepted, it will be added to [the issue tracker][2].
-Features and bug fixes that have already been merged and will be included
-in the next release are then "closed" and added to the [changelog][7].
-
-### Discussions, support, and help
+## Discussions, support, and help
 
 For general discussions, support, and help, please use the community
 spaces [listed on the sidebar of the Elixir website](https://elixir-lang.org/),
 such as forums, chat platforms, etc, where the wider community will be available
 to help you.
 
+## Proposing new features
+
+We encourage you to first propose new features in the community spaces
+listed above. These discussions help refine ideas and gather feedback before
+submission. Our website also includes [a general outline of the language
+history and its current development focus](https://elixir-lang.org/development.html).
+
+Once you are ready, you can submit your proposal to the [Elixir Core
+mailing list][3], either through the web interface or by subscribing to
+it at <elixir-lang-core+subscribe@googlegroups.com>. Remember to include
+a clear problem description, compare the proposed solution to existing
+alternatives in the Elixir ecosystem (and in other languages if possible),
+and consider the potential impact your changes will have on the codebase and
+community.
+
+Once a proposal is accepted, it will be added to [the issue tracker][2].
+Features and bug fixes that have already been merged and will be included
+in the next release are then "closed" and added to the [changelog][7]
+before release.
+
 ## Compiling from source
 
 For the many different ways to install Elixir,
@@ -109,125 +119,12 @@ variable `ERL_COMPILER_OPTIONS=deterministic`.
 
 ## Contributing
 
-We invite contributions to Elixir. To contribute, there are a few
-things you need to know about the code. First, Elixir code is divided
-by each application inside the `lib` folder:
-
-  * `elixir` - Elixir's kernel and standard library
-
-  * `eex` - EEx is the template engine that allows you to embed Elixir
-
-  * `ex_unit` - ExUnit is a simple test framework that ships with Elixir
-
-  * `iex` - IEx stands for Interactive Elixir: Elixir's interactive shell
-
-  * `logger` - Logger is the built-in logger
-
-  * `mix` - Mix is Elixir's build tool
-
-You can run all tests in the root directory with `make test`. You can
-also run tests for a specific framework with `make test_#{APPLICATION}`, for example,
-`make test_ex_unit`. If you just changed something in Elixir's standard
-library, you can run only that portion through `make test_stdlib`.
-
-If you are only changing one file, you can choose to compile and run tests
-for that specific file for faster development cycles. For example, if you
-are changing the String module, you can compile it and run its tests as:
-
-```sh
-bin/elixirc lib/elixir/lib/string.ex -o lib/elixir/ebin
-bin/elixir lib/elixir/test/elixir/string_test.exs
-```
-
-Some test files need their `test_helper.exs` to be explicitly required
-before, such as:
-
-```sh
-bin/elixir -r lib/logger/test/test_helper.exs lib/logger/test/logger_test.exs
-```
-
-You can also use the `LINE` env var to run a single test:
-
-```sh
-LINE=123 bin/elixir lib/elixir/test/elixir/string_test.exs
-````
-
-To recompile all (including Erlang modules):
-
-```sh
-make compile
-```
-
-After your changes are done, please remember to run `make format` to guarantee
-all files are properly formatted, then run the full suite with
-`make test`.
-
-If your contribution fails during the bootstrapping of the language,
-you can rebuild the language from scratch with:
-
-```sh
-make clean_elixir compile
-```
-
-Similarly, if you can not get Elixir to compile or the tests to pass after
-updating an existing checkout, run `make clean compile`. You can check
-[the official build status](https://github.com/elixir-lang/elixir/actions/workflows/ci.yml).
-More tasks can be found by reading the [Makefile](Makefile).
-
-With tests running and passing, you are ready to contribute to Elixir and
-[send a pull request](https://help.github.com/articles/using-pull-requests/).
-We have saved some excellent pull requests we have received in the past in
-case you are looking for some examples:
-
-  * [Implement Enum.member? - Pull request](https://github.com/elixir-lang/elixir/pull/992)
-  * [Add String.valid? - Pull request](https://github.com/elixir-lang/elixir/pull/1058)
-  * [Implement capture_io for ExUnit - Pull request](https://github.com/elixir-lang/elixir/pull/1059)
-
-### Reviewing changes
-
-Once a pull request is sent, the Elixir team will review your changes.
-We outline our process below to clarify the roles of everyone involved.
-
-All pull requests must be approved by two committers before being merged into
-the repository. If changes are necessary, the team will leave appropriate
-comments requesting changes to the code. Unfortunately, we cannot guarantee a
-pull request will be merged, even when modifications are requested, as the Elixir
-team will re-evaluate the contribution as it changes.
-
-Committers may also push style changes directly to your branch. If you would
-rather manage all changes yourself, you can disable the "Allow edits from maintainers"
-feature when submitting your pull request.
-
-The Elixir team may optionally assign someone to review a pull request.
-If someone is assigned, they must explicitly approve the code before
-another team member can merge it.
-
-When the review finishes, your pull request will be squashed and merged
-into the repository. If you have carefully organized your commits and
-believe they should be merged without squashing, please mention it in
-a comment.
-
-## Building documentation
-
-Building the documentation requires that [ExDoc](https://github.com/elixir-lang/ex_doc)
-is installed and built alongside Elixir:
-
-```sh
-# After cloning and compiling Elixir, in its parent directory:
-git clone https://github.com/elixir-lang/ex_doc.git
-cd ex_doc && ../elixir/bin/elixir ../elixir/bin/mix do deps.get + compile
-```
-
-Now go back to Elixir's root directory and run:
-
-```sh
-make docs                  # to generate HTML pages
-make docs DOCS_FORMAT=epub # to generate EPUB documents
-```
-
-This will produce documentation sets for `elixir`, `eex`, `ex_unit`, `iex`, `logger`,
-and `mix` under the `doc` directory. If you are planning to contribute documentation,
-[please check our best practices for writing documentation](https://hexdocs.pm/elixir/writing-documentation.html).
+Contributions to Elixir are always welcome! Before you get started, please check
+out our [CONTRIBUTING.md](CONTRIBUTING.md) file. There you will find detailed
+guidelines on how to set up your environment, run the test suite, format your
+code, and submit pull requests. We also include information on our review
+process, licensing requirements, and helpful tips to ensure a smooth
+contribution experience.
 
 ## Development links
 
@@ -250,6 +147,7 @@ and `mix` under the `doc` directory. If you are planning to contribute documenta
   [8]: https://groups.google.com/group/elixir-lang-ann
   [9]: SECURITY.md
   [10]: https://groups.google.com/forum/#!searchin/elixir-lang-ann/%5Bsecurity%5D%7Csort:date
+  [11]: OPEN_SOURCE_POLICY.md
 
 ## License
 
@@ -257,4 +155,4 @@ and `mix` under the `doc` directory. If you are planning to contribute documenta
 
 Elixir source code is released under Apache License 2.0.
 
-Check [NOTICE](NOTICE) and [LICENSE](LICENSE) files for more information.
+Check [LICENSE](LICENSE) file for more information.

RELEASE.md

@@ -1,3 +1,9 @@
+<!--
+  SPDX-License-Identifier: Apache-2.0
+  SPDX-FileCopyrightText: 2021 The Elixir Team
+  SPDX-FileCopyrightText: 2012 Plataformatec
+-->
+
 # Release process
 
 ## Shipping a new version
@@ -22,7 +28,7 @@
 
 ### In the new branch
 
-1. Comment out `CANONICAL=` in /Makefile
+1. Comment out `CANONICAL := main/` in /Makefile
 
 2. Update tables in /SECURITY.md and "Compatibility and Deprecations"
 
@@ -44,6 +50,6 @@
 
 2. Update `otp_release` checks in `/Makefile` and `/lib/elixir/src/elixir.erl`
 
-3. Update relevant CI workflows in `/.github/workflows/*.yml`
+3. Update relevant CI workflows in `/.github/workflows/*.yml` - for release workflows, outdated/recently added Erlang/OTP versions must run conditionally
 
 4. Remove `otp_release` version checks that are no longer needed

SECURITY.md

@@ -1,3 +1,9 @@
+<!--
+  SPDX-License-Identifier: Apache-2.0
+  SPDX-FileCopyrightText: 2021 The Elixir Team
+  SPDX-FileCopyrightText: 2012 Plataformatec
+-->
+
 # Security Policy
 
 ## Supported versions
@@ -6,11 +12,11 @@ Elixir applies bug fixes only to the latest minor branch. Security patches are a
 
 Elixir version | Support
 :------------- | :-----------------------------
-1.18           | Bug fixes and security patches
+1.19           | Bug fixes and security patches
+1.18           | Security patches only
 1.17           | Security patches only
 1.16           | Security patches only
 1.15           | Security patches only
-1.14           | Security patches only
 
 ## Announcements
 

VERSION

@@ -1 +1 @@
-1.18.4
+1.19.5

bin/elixir

@@ -1,7 +1,12 @@
 #!/bin/sh
+
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 set -e
 
-ELIXIR_VERSION=1.18.4
+ELIXIR_VERSION=1.19.5
 
 if [ $# -eq 0 ] || { [ $# -eq 1 ] && { [ "$1" = "--help" ] || [ "$1" = "-h" ]; }; }; then
   cat <<USAGE >&2
@@ -216,10 +221,6 @@ SCRIPT_PATH=$(dirname "$SELF")
 if [ "$OSTYPE" = "cygwin" ]; then SCRIPT_PATH=$(cygpath -m "$SCRIPT_PATH"); fi
 if [ "$MODE" != "iex" ]; then ERL="-s elixir start_cli $ERL"; fi
 
-if [ "$OS" != "Windows_NT" ] && [ -z "$NO_COLOR" ]; then
-  if test -t 1 -a -t 2; then ERL="-elixir ansi_enabled true $ERL"; fi
-fi
-
 # One MAY change ERTS_BIN= but you MUST NOT change
 # ERTS_BIN=$ERTS_BIN as it is handled by Elixir releases.
 ERTS_BIN=

bin/elixir.bat

@@ -1,6 +1,10 @@
 @echo off
 
-set ELIXIR_VERSION=1.18.4
+:: SPDX-License-Identifier: Apache-2.0
+:: SPDX-FileCopyrightText: 2021 The Elixir Team
+:: SPDX-FileCopyrightText: 2012 Plataformatec
+
+set ELIXIR_VERSION=1.19.5
 
 if    ""%1""==""""                if ""%2""=="""" goto documentation
 if /I ""%1""==""--help""          if ""%2""=="""" goto documentation

bin/elixirc

@@ -1,4 +1,9 @@
 #!/bin/sh
+
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 set -e
 
 if [ $# -eq 0 ] || [ "$1" = "--help" ] || [ "$1" = "-h" ]; then

bin/elixirc.bat

@@ -1,4 +1,9 @@
 @echo off
+
+:: SPDX-License-Identifier: Apache-2.0
+:: SPDX-FileCopyrightText: 2021 The Elixir Team
+:: SPDX-FileCopyrightText: 2012 Plataformatec
+
 setlocal
 set argc=0
 for %%A in (%*) do (

bin/iex

@@ -1,4 +1,9 @@
 #!/bin/sh
+
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 set -e
 
 if [ "$1" = "--help" ] || [ "$1" = "-h" ]; then

bin/iex.bat

@@ -1,4 +1,9 @@
 @echo off
+
+:: SPDX-License-Identifier: Apache-2.0
+:: SPDX-FileCopyrightText: 2021 The Elixir Team
+:: SPDX-FileCopyrightText: 2012 Plataformatec
+
 setlocal
 if /I ""%1""==""--help"" goto documentation
 if /I ""%1""==""-h""     goto documentation

bin/mix

@@ -1,2 +1,7 @@
 #!/usr/bin/env elixir
+
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 Mix.CLI.main()

bin/mix.bat

@@ -1,2 +1,7 @@
 @echo off
+
+:: SPDX-License-Identifier: Apache-2.0
+:: SPDX-FileCopyrightText: 2021 The Elixir Team
+:: SPDX-FileCopyrightText: 2012 Plataformatec
+
 call "%~dp0\elixir.bat" "%~dp0\mix" %*

bin/mix.ps1

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 # Store path to mix.bat as a FileInfo object
 $mixBatPath = (Get-ChildItem (((Get-ChildItem $MyInvocation.MyCommand.Path).Directory.FullName) + '\mix.bat'))
 $newArgs = @()

lib/eex/lib/eex.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule EEx.SyntaxError do
   defexception [:file, :line, :column, :snippet, message: "syntax error"]
 
@@ -114,6 +118,19 @@ defmodule EEx do
           | {:expr | :start_expr | :middle_expr | :end_expr, marker, charlist, metadata}
           | {:eof, metadata}
 
+  @type tokenize_opt ::
+          {:file, binary()}
+          | {:line, line}
+          | {:column, column}
+          | {:indentation, non_neg_integer}
+          | {:trim, boolean()}
+
+  @type compile_opt ::
+          tokenize_opt
+          | {:engine, module()}
+          | {:parser_options, Code.parser_opts()}
+          | {atom(), term()}
+
   @doc """
   Generates a function definition from the given string.
 
@@ -124,6 +141,7 @@ defmodule EEx do
   template.
 
   The supported `options` are described [in the module docs](#module-options).
+  Additional options are passed to the underlying engine.
 
   ## Examples
 
@@ -216,9 +234,11 @@ defmodule EEx do
       "3"
 
   """
-  @spec compile_string(String.t(), keyword) :: Macro.t()
+  @spec compile_string(String.t(), [compile_opt]) :: Macro.t()
   def compile_string(source, options \\ []) when is_binary(source) and is_list(options) do
-    case tokenize(source, options) do
+    tokenize_opts = Keyword.take(options, [:file, :line, :column, :indentation, :trim])
+
+    case tokenize(source, tokenize_opts) do
       {:ok, tokens} ->
         EEx.Compiler.compile(tokens, source, options)
 
@@ -255,7 +275,7 @@ defmodule EEx do
       #=> "3"
 
   """
-  @spec compile_file(Path.t(), keyword) :: Macro.t()
+  @spec compile_file(Path.t(), [compile_opt]) :: Macro.t()
   def compile_file(filename, options \\ []) when is_list(options) do
     filename = IO.chardata_to_string(filename)
     options = Keyword.merge([file: filename, line: 1], options)
@@ -273,7 +293,7 @@ defmodule EEx do
       "foo baz"
 
   """
-  @spec eval_string(String.t(), keyword, keyword) :: String.t()
+  @spec eval_string(String.t(), keyword, [compile_opt]) :: String.t()
   def eval_string(source, bindings \\ [], options \\ [])
       when is_binary(source) and is_list(bindings) and is_list(options) do
     compiled = compile_string(source, options)
@@ -295,7 +315,7 @@ defmodule EEx do
       #=> "foo baz"
 
   """
-  @spec eval_file(Path.t(), keyword, keyword) :: String.t()
+  @spec eval_file(Path.t(), keyword, [compile_opt]) :: String.t()
   def eval_file(filename, bindings \\ [], options \\ [])
       when is_list(bindings) and is_list(options) do
     filename = IO.chardata_to_string(filename)
@@ -335,7 +355,7 @@ defmodule EEx do
   Note new tokens may be added in the future.
   """
   @doc since: "1.14.0"
-  @spec tokenize([char()] | String.t(), opts :: keyword) ::
+  @spec tokenize([char()] | String.t(), [tokenize_opt]) ::
           {:ok, [token()]} | {:error, String.t(), metadata()}
   def tokenize(contents, opts \\ []) do
     EEx.Compiler.tokenize(contents, opts)

lib/eex/lib/eex/compiler.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule EEx.Compiler do
   @moduledoc false
 
@@ -300,7 +304,7 @@ defmodule EEx.Compiler do
       source: source,
       line: line,
       quoted: [],
-      parser_options: parser_options,
+      parser_options: [indentation: indentation] ++ parser_options,
       indentation: indentation
     }
 

lib/eex/lib/eex/engine.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule EEx.Engine do
   @moduledoc ~S"""
   Basic EEx engine that ships with Elixir.
@@ -13,6 +17,10 @@ defmodule EEx.Engine do
   @doc """
   Called at the beginning of every template.
 
+  It receives the options during compilation, including the
+  ones managed by EEx, such as `:line` and `:file`, as well
+  as custom engine options.
+
   It must return the initial state.
   """
   @callback init(opts :: keyword) :: state

lib/eex/lib/eex/smart_engine.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule EEx.SmartEngine do
   @moduledoc """
   The default engine used by EEx.

lib/eex/mix.exs

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule EEx.MixProject do
   use Mix.Project
 

lib/eex/test/eex/smart_engine_test.exs

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 Code.require_file("../test_helper.exs", __DIR__)
 
 defmodule EEx.SmartEngineTest do

lib/eex/test/eex/tokenizer_test.exs

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 Code.require_file("../test_helper.exs", __DIR__)
 
 defmodule EEx.TokenizerTest do

lib/eex/test/eex_test.exs

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 Code.require_file("test_helper.exs", __DIR__)
 
 require EEx
@@ -498,6 +502,59 @@ defmodule EExTest do
       end
     end
 
+    test "from Elixir parser" do
+      line = __ENV__.line + 6
+
+      message =
+        assert_raise TokenMissingError, fn ->
+          EEx.compile_string(
+            """
+            <li>
+              <strong>Some:</strong>
+              <%= true && @some[ %>
+            </li>
+            """,
+            file: __ENV__.file,
+            line: line,
+            indentation: 12
+          )
+        end
+
+      assert message |> Exception.message() |> strip_ansi() =~ """
+                  │
+              514 │                   true && @some[\s
+                  │                                │ └ missing closing delimiter (expected "]")
+                  │                                └ unclosed delimiter
+             """
+    end
+
+    test "from Elixir parser with line breaks" do
+      line = __ENV__.line + 6
+
+      message =
+        assert_raise TokenMissingError, fn ->
+          EEx.compile_string(
+            """
+            <li>
+              <strong>Some:</strong>
+              <%= true &&
+                @some[ %>
+            </li>
+            """,
+            file: __ENV__.file,
+            line: line,
+            indentation: 12
+          )
+        end
+
+      assert message |> Exception.message() |> strip_ansi() =~ """
+                  │
+              #{line + 3} │                 @some[\s
+                  │                      │ └ missing closing delimiter (expected "]")
+                  │                      └ unclosed delimiter
+             """
+    end
+
     test "honor line numbers" do
       assert_raise EEx.SyntaxError,
                    "nofile:100:6: expected closing '%>' for EEx expression",
@@ -860,13 +917,13 @@ defmodule EExTest do
       file = to_charlist(Path.relative_to_cwd(__ENV__.file))
 
       assert EExTest.Compiled.before_compile() ==
-               {7, {EExTest.Compiled, :before_compile, 0, [file: file, line: 7]}}
+               {11, {EExTest.Compiled, :before_compile, 0, [file: file, line: 11]}}
 
       assert EExTest.Compiled.after_compile() ==
-               {21, {EExTest.Compiled, :after_compile, 0, [file: file, line: 21]}}
+               {25, {EExTest.Compiled, :after_compile, 0, [file: file, line: 25]}}
 
       assert EExTest.Compiled.unknown() ==
-               {26, {EExTest.Compiled, :unknown, 0, [file: ~c"unknown", line: 26]}}
+               {30, {EExTest.Compiled, :unknown, 0, [file: ~c"unknown", line: 30]}}
     end
   end
 
@@ -944,6 +1001,12 @@ defmodule EExTest do
     end
   end
 
+  @strip_ansi [IO.ANSI.green(), IO.ANSI.red(), IO.ANSI.reset()]
+
+  defp strip_ansi(doc) do
+    String.replace(doc, @strip_ansi, "")
+  end
+
   defp assert_eval(expected, actual, binding \\ [], opts \\ []) do
     opts = Keyword.merge([file: __ENV__.file, engine: opts[:engine] || EEx.Engine], opts)
     result = EEx.eval_string(actual, binding, opts)

lib/eex/test/test_helper.exs

@@ -1,6 +1,13 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 {line_exclude, line_include} =
   if line = System.get_env("LINE"), do: {[:test], [line: line]}, else: {[], []}
 
+Code.require_file("../../elixir/scripts/cover_record.exs", __DIR__)
+CoverageRecorder.maybe_record("eex")
+
 ExUnit.start(
   trace: !!System.get_env("TRACE"),
   include: line_include,

lib/elixir/Emakefile

@@ -1,3 +1,7 @@
+%% SPDX-License-Identifier: Apache-2.0
+%% SPDX-FileCopyrightText: 2021 The Elixir Team
+%% SPDX-FileCopyrightText: 2012 Plataformatec
+
 {'src/*', [
   warn_unused_vars,
   warn_export_all,

lib/elixir/lib/access.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Access do
   @moduledoc """
   Key-based access to data structures.
@@ -513,8 +517,8 @@ defmodule Access do
   An error is raised if the accessed structure is not a map or a struct:
 
       iex> get_in([], [Access.key(:foo)])
-      ** (BadMapError) expected a map, got: []
-
+      ** (BadMapError) expected a map, got:
+      ...
   """
   @spec key(key, term) :: access_fun(data :: struct | map, current_value :: term)
   def key(key, default \\ nil) do
@@ -552,7 +556,8 @@ defmodule Access do
       iex> pop_in(map, [Access.key!(:user), Access.key!(:name)])
       {"john", %{user: %{}}}
       iex> get_in(map, [Access.key!(:user), Access.key!(:unknown)])
-      ** (KeyError) key :unknown not found in: %{name: \"john\"}
+      ** (KeyError) key :unknown not found in:
+      ...
 
   The examples above could be partially written as:
 
@@ -807,7 +812,7 @@ defmodule Access do
       iex> get_in([:a, :b, :c], [Access.at!(2)])
       :c
       iex> get_in([:a, :b, :c], [Access.at!(3)])
-      ** (Enum.OutOfBoundsError) out of bounds error
+      ** (Enum.OutOfBoundsError) out of bounds error at position 3 when traversing enumerable [:a, :b, :c]
 
   """
   @doc since: "1.11.0"
@@ -819,12 +824,14 @@ defmodule Access do
   defp at!(:get, data, index, next) when is_list(data) do
     case Enum.fetch(data, index) do
       {:ok, value} -> next.(value)
-      :error -> raise Enum.OutOfBoundsError
+      :error -> raise Enum.OutOfBoundsError, index: index, enumerable: data
     end
   end
 
   defp at!(:get_and_update, data, index, next) when is_list(data) do
-    get_and_update_at(data, index, next, [], fn -> raise Enum.OutOfBoundsError end)
+    get_and_update_at(data, index, next, [], fn ->
+      raise Enum.OutOfBoundsError, index: index, enumerable: data
+    end)
   end
 
   defp at!(_op, data, _index, _next) do
@@ -884,7 +891,7 @@ defmodule Access do
   end
 
   defp filter(:get, data, func, next) when is_list(data) do
-    data |> Enum.filter(func) |> Enum.map(next)
+    for elem <- data, func.(elem), do: next.(elem)
   end
 
   defp filter(:get_and_update, data, func, next) when is_list(data) do
@@ -992,6 +999,93 @@ defmodule Access do
     raise ArgumentError, "Access.slice/1 expected a list, got: #{inspect(data)}"
   end
 
+  @doc """
+  Returns a function that accesses all values in a map or a keyword list.
+
+  The returned function is typically passed as an accessor to `Kernel.get_in/2`,
+  `Kernel.get_and_update_in/3`, and friends.
+
+  ## Examples
+
+      iex> users = %{"john" => %{age: 27}, "meg" => %{age: 23}}
+      iex> get_in(users, [Access.values(), :age]) |> Enum.sort()
+      [23, 27]
+      iex> update_in(users, [Access.values(), :age], fn age -> age + 1 end)
+      %{"john" => %{age: 28}, "meg" => %{age: 24}}
+      iex> put_in(users, [Access.values(), :planet], "Earth")
+      %{"john" => %{age: 27, planet: "Earth"}, "meg" => %{age: 23, planet: "Earth"}}
+
+  Values in keyword lists can be accessed as well:
+
+      iex> users = [john: %{age: 27}, meg: %{age: 23}]
+      iex> get_and_update_in(users, [Access.values(), :age], fn age -> {age, age + 1} end)
+      {[27, 23], [john: %{age: 28}, meg: %{age: 24}]}
+
+  By returning `:pop` from an accessor function, you can remove the accessed key and value
+  from the map or keyword list:
+
+      iex> require Integer
+      iex> numbers = [one: 1, two: 2, three: 3, four: 4]
+      iex> get_and_update_in(numbers, [Access.values()], fn num ->
+      ...>   if Integer.is_even(num), do: :pop, else: {num, to_string(num)}
+      ...> end)
+      {[1, 2, 3, 4], [one: "1", three: "3"]}
+
+  An error is raised if the accessed structure is not a map nor a keyword list:
+
+      iex> get_in([1, 2, 3], [Access.values()])
+      ** (RuntimeError) Access.values/0 expected a map or a keyword list, got: [1, 2, 3]
+  """
+  @doc since: "1.19.0"
+  @spec values() :: Access.access_fun(data :: map() | keyword(), current_value :: list())
+  def values do
+    &values/3
+  end
+
+  defp values(:get, data = %{}, next) do
+    Enum.map(data, fn {_key, value} -> next.(value) end)
+  end
+
+  defp values(:get_and_update, data = %{}, next) do
+    {reverse_gets, updated_data} =
+      Enum.reduce(data, {[], %{}}, fn {key, value}, {gets, data_acc} ->
+        case next.(value) do
+          {get, update} -> {[get | gets], Map.put(data_acc, key, update)}
+          :pop -> {[value | gets], data_acc}
+        end
+      end)
+
+    {Enum.reverse(reverse_gets), updated_data}
+  end
+
+  defp values(op, data = [], next) do
+    values_keyword(op, data, next)
+  end
+
+  defp values(op, data = [{key, _value} | _tail], next) when is_atom(key) do
+    values_keyword(op, data, next)
+  end
+
+  defp values(_op, data, _next) do
+    raise "Access.values/0 expected a map or a keyword list, got: #{inspect(data)}"
+  end
+
+  defp values_keyword(:get, data, next) do
+    Enum.map(data, fn {key, value} when is_atom(key) -> next.(value) end)
+  end
+
+  defp values_keyword(:get_and_update, data, next) do
+    {reverse_gets, reverse_updated_data} =
+      Enum.reduce(data, {[], []}, fn {key, value}, {gets, data_acc} when is_atom(key) ->
+        case next.(value) do
+          {get, update} -> {[get | gets], [{key, update} | data_acc]}
+          :pop -> {[value | gets], data_acc}
+        end
+      end)
+
+    {Enum.reverse(reverse_gets), Enum.reverse(reverse_updated_data)}
+  end
+
   defp normalize_range(%Range{first: first, last: last, step: step}, list)
        when first < 0 or last < 0 do
     count = length(list)
@@ -1038,9 +1132,9 @@ defmodule Access do
       iex> list = [%{name: "john", salary: 10}, %{name: "francine", salary: 30}]
       iex> get_in(list, [Access.find(&(&1.salary > 20)), :name])
       "francine"
-      iex>  get_and_update_in(list, [Access.find(&(&1.salary <= 40)), :name], fn prev ->
-      ...> {prev, String.upcase(prev)}
-      ...>  end)
+      iex> get_and_update_in(list, [Access.find(&(&1.salary <= 40)), :name], fn prev ->
+      ...>   {prev, String.upcase(prev)}
+      ...> end)
       {"john", [%{name: "JOHN", salary: 10}, %{name: "francine", salary: 30}]}
 
   `find/1` can also be used to pop the first found element out of a list or
@@ -1067,7 +1161,7 @@ defmodule Access do
 
   An error is raised if the accessed structure is not a list:
 
-      iex>  get_in(%{}, [Access.find(fn a -> a == 10 end)])
+      iex> get_in(%{}, [Access.find(fn a -> a == 10 end)])
       ** (RuntimeError) Access.find/1 expected a list, got: %{}
   """
   @doc since: "1.17.0"

lib/elixir/lib/agent.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Agent do
   @moduledoc """
   Agents are a simple abstraction around state.

lib/elixir/lib/agent/server.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Agent.Server do
   @moduledoc false
 

lib/elixir/lib/application.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Application do
   @moduledoc """
   A module for working with applications and defining application callbacks.
@@ -243,7 +247,7 @@ defmodule Application do
   invoked if it hasn't been done yet. Then, it checks if the dependencies listed
   in the `applications` key of the resource file are already started. Having at
   least one dependency not started is an error condition. Functions like
-  `ensure_all_started/1` takes care of starting an application and all of its
+  `ensure_all_started/1` take care of starting an application and all of its
   dependencies for you.
 
   If the application does not have a callback module configured, starting is
@@ -908,8 +912,7 @@ defmodule Application do
       `:permanent`, or `:transient`. See `t:restart_type/1` for more information.
 
     * `:mode` - (since v1.15.0) if the applications should be started serially
-      (`:serial`, default) or concurrently (`:concurrent`). This option requires
-      Erlang/OTP 26+.
+      (`:serial`, default) or concurrently (`:concurrent`).
 
   """
   @spec ensure_all_started(app | [app], type: restart_type(), mode: :serial | :concurrent) ::
@@ -930,18 +933,7 @@ defmodule Application do
 
   def ensure_all_started(apps, opts) when is_list(apps) and is_list(opts) do
     opts = Keyword.validate!(opts, type: :temporary, mode: :serial)
-
-    if function_exported?(:application, :ensure_all_started, 3) do
-      :application.ensure_all_started(apps, opts[:type], opts[:mode])
-    else
-      # TODO: Remove this clause when we require Erlang/OTP 26+
-      Enum.reduce_while(apps, {:ok, []}, fn app, {:ok, acc} ->
-        case :application.ensure_all_started(app, opts[:type]) do
-          {:ok, apps} -> {:cont, {:ok, apps ++ acc}}
-          {:error, e} -> {:halt, {:error, e}}
-        end
-      end)
-    end
+    :application.ensure_all_started(apps, opts[:type], opts[:mode])
   end
 
   @doc """

lib/elixir/lib/atom.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Atom do
   @moduledoc """
   Atoms are constants whose values are their own name.

lib/elixir/lib/base.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Base do
   import Bitwise
 
@@ -315,58 +319,126 @@ defmodule Base do
             "Double check your string for unwanted characters or pad it accordingly"
   end
 
+  @doc """
+  Checks if a string is a valid base 16 encoded string.
+
+  > #### When to use this {: .tip}
+  >
+  > Use this function when you just need to *validate* that a string is
+  > valid base 16 data, without actually producing a decoded output string.
+  > This function is both more performant and memory efficient than using
+  > `decode16/2`, checking that the result is `{:ok, ...}`, and then
+  > discarding the decoded binary.
+
+  ## Options
+
+  Accepts the same options as `decode16/2`.
+
+  ## Examples
+
+      iex> Base.valid16?("666F6F626172")
+      true
+
+      iex> Base.valid16?("666f6f626172", case: :lower)
+      true
+
+      iex> Base.valid16?("666f6F626172", case: :mixed)
+      true
+
+      iex> Base.valid16?("ff", case: :upper)
+      false
+
+  """
+  @doc since: "1.19.0"
+  @spec valid16?(binary, case: decode_case) :: boolean
+  def valid16?(string, opts \\ [])
+
+  def valid16?(string, opts) when is_binary(string) and rem(byte_size(string), 2) == 0 do
+    case Keyword.get(opts, :case, :upper) do
+      :upper -> validate16upper?(string)
+      :lower -> validate16lower?(string)
+      :mixed -> validate16mixed?(string)
+    end
+  end
+
+  def valid16?(string, _opts) when is_binary(string) do
+    false
+  end
+
   upper = Enum.with_index(b16_alphabet)
 
   for {base, alphabet} <- [upper: upper, lower: to_lower_dec.(upper), mixed: to_mixed_dec.(upper)] do
-    name = :"decode16#{base}!"
+    decode_name = :"decode16#{base}!"
+    validate_name = :"validate16#{base}?"
+    valid_char_name = :"valid_char16#{base}?"
+
     {min, decoded} = to_decode_list.(alphabet)
 
-    defp unquote(name)(char) do
-      try do
-        elem({unquote_splicing(decoded)}, char - unquote(min))
-      rescue
-        _ -> bad_character!(char)
-      else
-        nil -> bad_character!(char)
-        char -> char
+    defp unquote(validate_name)(<<>>), do: true
+
+    defp unquote(validate_name)(<<c1, c2, rest::binary>>) do
+      unquote(valid_char_name)(c1) and
+        unquote(valid_char_name)(c2) and
+        unquote(validate_name)(rest)
+    end
+
+    defp unquote(validate_name)(<<_char, _rest::binary>>), do: false
+
+    @compile {:inline, [{valid_char_name, 1}]}
+    defp unquote(valid_char_name)(char)
+         when elem({unquote_splicing(decoded)}, char - unquote(min)) != nil,
+         do: true
+
+    defp unquote(valid_char_name)(_char), do: false
+
+    defp unquote(decode_name)(char) do
+      index = char - unquote(min)
+
+      cond do
+        index not in 0..unquote(length(decoded) - 1) -> bad_character!(char)
+        new_char = elem({unquote_splicing(decoded)}, index) -> new_char
+        true -> bad_character!(char)
       end
     end
 
-    defp unquote(name)(<<c1, c2, c3, c4, c5, c6, c7, c8, rest::binary>>, acc) do
-      unquote(name)(
+    defp unquote(decode_name)(<<c1, c2, c3, c4, c5, c6, c7, c8, rest::binary>>, acc) do
+      unquote(decode_name)(
         rest,
         <<
           acc::binary,
-          unquote(name)(c1)::4,
-          unquote(name)(c2)::4,
-          unquote(name)(c3)::4,
-          unquote(name)(c4)::4,
-          unquote(name)(c5)::4,
-          unquote(name)(c6)::4,
-          unquote(name)(c7)::4,
-          unquote(name)(c8)::4
+          unquote(decode_name)(c1)::4,
+          unquote(decode_name)(c2)::4,
+          unquote(decode_name)(c3)::4,
+          unquote(decode_name)(c4)::4,
+          unquote(decode_name)(c5)::4,
+          unquote(decode_name)(c6)::4,
+          unquote(decode_name)(c7)::4,
+          unquote(decode_name)(c8)::4
         >>
       )
     end
 
-    defp unquote(name)(<<c1, c2, c3, c4, rest::binary>>, acc) do
-      unquote(name)(
+    defp unquote(decode_name)(<<c1, c2, c3, c4, rest::binary>>, acc) do
+      unquote(decode_name)(
         rest,
         <<
           acc::binary,
-          unquote(name)(c1)::4,
-          unquote(name)(c2)::4,
-          unquote(name)(c3)::4,
-          unquote(name)(c4)::4
+          unquote(decode_name)(c1)::4,
+          unquote(decode_name)(c2)::4,
+          unquote(decode_name)(c3)::4,
+          unquote(decode_name)(c4)::4
         >>
       )
     end
 
-    defp unquote(name)(<<c1::8, c2::8, rest::binary>>, acc) do
-      unquote(name)(rest, <<acc::binary, unquote(name)(c1)::4, unquote(name)(c2)::4>>)
+    defp unquote(decode_name)(<<c1::8, c2::8, rest::binary>>, acc) do
+      unquote(decode_name)(
+        rest,
+        <<acc::binary, unquote(decode_name)(c1)::4, unquote(decode_name)(c2)::4>>
+      )
     end
 
-    defp unquote(name)(<<>>, acc) do
+    defp unquote(decode_name)(<<>>, acc) do
       acc
     end
   end
@@ -555,6 +627,40 @@ defmodule Base do
     string |> remove_ignored(opts[:ignore]) |> decode64base!(pad?)
   end
 
+  @doc """
+  Validates a base 64 encoded string.
+
+  > #### When to use this {: .tip}
+  >
+  > Use this function when you just need to *validate* that a string is
+  > valid base 64 data, without actually producing a decoded output string.
+  > This function is both more performant and memory efficient than using
+  > `decode64/2`, checking that the result is `{:ok, ...}`, and then
+  > discarding the decoded binary.
+
+  ## Options
+
+  Accepts the same options as `decode64/2`.
+
+  ## Examples
+
+      iex> Base.valid64?("Zm9vYmFy")
+      true
+
+      iex> Base.valid64?("Zm9vYmFy\\n", ignore: :whitespace)
+      true
+
+      iex> Base.valid64?("Zm9vYg==")
+      true
+
+  """
+  @doc since: "1.19.0"
+  @spec valid64?(binary, ignore: :whitespace, padding: boolean) :: boolean
+  def valid64?(string, opts \\ []) when is_binary(string) do
+    pad? = Keyword.get(opts, :padding, true)
+    string |> remove_ignored(opts[:ignore]) |> validate64base?(pad?)
+  end
+
   @doc """
   Decodes a base 64 encoded string with URL and filename safe alphabet
   into a binary string.
@@ -615,120 +721,266 @@ defmodule Base do
     string |> remove_ignored(opts[:ignore]) |> decode64url!(pad?)
   end
 
+  @doc """
+  Validates a base 64 encoded string with URL and filename safe alphabet.
+
+  > #### When to use this {: .tip}
+  >
+  > Use this function when you just need to *validate* that a string is
+  > valid (URL-safe) base 64 data, without actually producing a decoded
+  > output string. This function is both more performant and memory efficient
+  > than using `url_decode64/2`, checking that the result is `{:ok, ...}`,
+  > and then discarding the decoded binary.
+
+  ## Options
+
+  Accepts the same options as `url_decode64/2`.
+
+  ## Examples
+
+      iex> Base.url_valid64?("_3_-_A==")
+      true
+
+      iex> Base.url_valid64?("_3_-_A==\\n", ignore: :whitespace)
+      true
+
+      iex> Base.url_valid64?("_3_-_A", padding: false)
+      true
+
+  """
+  @doc since: "1.19.0"
+  @spec url_valid64?(binary, ignore: :whitespace, padding: boolean) :: boolean
+  def url_valid64?(string, opts \\ []) when is_binary(string) do
+    pad? = Keyword.get(opts, :padding, true)
+    string |> remove_ignored(opts[:ignore]) |> validate64url?(pad?)
+  end
+
   for {base, alphabet} <- [base: b64_alphabet, url: b64url_alphabet] do
-    name = :"decode64#{base}!"
+    decode_name = :"decode64#{base}!"
+
+    validate_name = :"validate64#{base}?"
+    validate_main_name = :"validate_main64#{validate_name}?"
+    valid_char_name = :"valid_char64#{base}?"
     {min, decoded} = alphabet |> Enum.with_index() |> to_decode_list.()
 
-    defp unquote(name)(char) do
-      try do
-        elem({unquote_splicing(decoded)}, char - unquote(min))
-      rescue
-        _ -> bad_character!(char)
-      else
-        nil -> bad_character!(char)
-        char -> char
+    defp unquote(validate_main_name)(<<>>), do: true
+
+    defp unquote(validate_main_name)(
+           <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8, c8::8, rest::binary>>
+         ) do
+      unquote(valid_char_name)(c1) and
+        unquote(valid_char_name)(c2) and
+        unquote(valid_char_name)(c3) and
+        unquote(valid_char_name)(c4) and
+        unquote(valid_char_name)(c5) and
+        unquote(valid_char_name)(c6) and
+        unquote(valid_char_name)(c7) and
+        unquote(valid_char_name)(c8) and
+        unquote(validate_main_name)(rest)
+    end
+
+    defp unquote(validate_name)(<<>>, _pad?), do: true
+
+    defp unquote(validate_name)(string, pad?) do
+      segs = div(byte_size(string) + 7, 8) - 1
+      <<main::size(^segs)-binary-unit(64), rest::binary>> = string
+      main_valid? = unquote(validate_main_name)(main)
+
+      case rest do
+        _ when not main_valid? ->
+          false
+
+        <<c1::8, c2::8, ?=, ?=>> ->
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2)
+
+        <<c1::8, c2::8, c3::8, ?=>> ->
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3)
+
+        <<c1::8, c2::8, c3::8, c4::8>> ->
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3) and
+            unquote(valid_char_name)(c4)
+
+        <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, ?=, ?=>> ->
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3) and
+            unquote(valid_char_name)(c4) and
+            unquote(valid_char_name)(c5) and
+            unquote(valid_char_name)(c6)
+
+        <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8, ?=>> ->
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3) and
+            unquote(valid_char_name)(c4) and
+            unquote(valid_char_name)(c5) and
+            unquote(valid_char_name)(c6) and
+            unquote(valid_char_name)(c7)
+
+        <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8, c8::8>> ->
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3) and
+            unquote(valid_char_name)(c4) and
+            unquote(valid_char_name)(c5) and
+            unquote(valid_char_name)(c6) and
+            unquote(valid_char_name)(c7) and
+            unquote(valid_char_name)(c8)
+
+        <<c1::8, c2::8>> when not pad? ->
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2)
+
+        <<c1::8, c2::8, c3::8>> when not pad? ->
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3)
+
+        <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8>> when not pad? ->
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3) and
+            unquote(valid_char_name)(c4) and
+            unquote(valid_char_name)(c5) and
+            unquote(valid_char_name)(c6)
+
+        <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8>> when not pad? ->
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3) and
+            unquote(valid_char_name)(c4) and
+            unquote(valid_char_name)(c5) and
+            unquote(valid_char_name)(c6) and
+            unquote(valid_char_name)(c7)
+
+        _ ->
+          false
       end
     end
 
-    defp unquote(name)(<<>>, _pad?), do: <<>>
+    @compile {:inline, [{valid_char_name, 1}]}
+    defp unquote(valid_char_name)(char)
+         when elem({unquote_splicing(decoded)}, char - unquote(min)) != nil,
+         do: true
 
-    defp unquote(name)(string, pad?) do
+    defp unquote(valid_char_name)(_char), do: false
+
+    defp unquote(decode_name)(char) do
+      index = char - unquote(min)
+
+      cond do
+        index not in 0..unquote(length(decoded) - 1) -> bad_character!(char)
+        new_char = elem({unquote_splicing(decoded)}, index) -> new_char
+        true -> bad_character!(char)
+      end
+    end
+
+    defp unquote(decode_name)(<<>>, _pad?), do: <<>>
+
+    defp unquote(decode_name)(string, pad?) do
       segs = div(byte_size(string) + 7, 8) - 1
       <<main::size(^segs)-binary-unit(64), rest::binary>> = string
 
       main =
         for <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8, c8::8 <- main>>, into: <<>> do
           <<
-            unquote(name)(c1)::6,
-            unquote(name)(c2)::6,
-            unquote(name)(c3)::6,
-            unquote(name)(c4)::6,
-            unquote(name)(c5)::6,
-            unquote(name)(c6)::6,
-            unquote(name)(c7)::6,
-            unquote(name)(c8)::6
+            unquote(decode_name)(c1)::6,
+            unquote(decode_name)(c2)::6,
+            unquote(decode_name)(c3)::6,
+            unquote(decode_name)(c4)::6,
+            unquote(decode_name)(c5)::6,
+            unquote(decode_name)(c6)::6,
+            unquote(decode_name)(c7)::6,
+            unquote(decode_name)(c8)::6
           >>
         end
 
       case rest do
         <<c1::8, c2::8, ?=, ?=>> ->
-          <<main::bits, unquote(name)(c1)::6, bsr(unquote(name)(c2), 4)::2>>
+          <<main::bits, unquote(decode_name)(c1)::6, bsr(unquote(decode_name)(c2), 4)::2>>
 
         <<c1::8, c2::8, c3::8, ?=>> ->
-          <<main::bits, unquote(name)(c1)::6, unquote(name)(c2)::6, bsr(unquote(name)(c3), 2)::4>>
+          <<main::bits, unquote(decode_name)(c1)::6, unquote(decode_name)(c2)::6,
+            bsr(unquote(decode_name)(c3), 2)::4>>
 
         <<c1::8, c2::8, c3::8, c4::8>> ->
           <<
             main::bits,
-            unquote(name)(c1)::6,
-            unquote(name)(c2)::6,
-            unquote(name)(c3)::6,
-            unquote(name)(c4)::6
+            unquote(decode_name)(c1)::6,
+            unquote(decode_name)(c2)::6,
+            unquote(decode_name)(c3)::6,
+            unquote(decode_name)(c4)::6
           >>
 
         <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, ?=, ?=>> ->
           <<
             main::bits,
-            unquote(name)(c1)::6,
-            unquote(name)(c2)::6,
-            unquote(name)(c3)::6,
-            unquote(name)(c4)::6,
-            unquote(name)(c5)::6,
-            bsr(unquote(name)(c6), 4)::2
+            unquote(decode_name)(c1)::6,
+            unquote(decode_name)(c2)::6,
+            unquote(decode_name)(c3)::6,
+            unquote(decode_name)(c4)::6,
+            unquote(decode_name)(c5)::6,
+            bsr(unquote(decode_name)(c6), 4)::2
           >>
 
         <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8, ?=>> ->
           <<
             main::bits,
-            unquote(name)(c1)::6,
-            unquote(name)(c2)::6,
-            unquote(name)(c3)::6,
-            unquote(name)(c4)::6,
-            unquote(name)(c5)::6,
-            unquote(name)(c6)::6,
-            bsr(unquote(name)(c7), 2)::4
+            unquote(decode_name)(c1)::6,
+            unquote(decode_name)(c2)::6,
+            unquote(decode_name)(c3)::6,
+            unquote(decode_name)(c4)::6,
+            unquote(decode_name)(c5)::6,
+            unquote(decode_name)(c6)::6,
+            bsr(unquote(decode_name)(c7), 2)::4
           >>
 
         <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8, c8::8>> ->
           <<
             main::bits,
-            unquote(name)(c1)::6,
-            unquote(name)(c2)::6,
-            unquote(name)(c3)::6,
-            unquote(name)(c4)::6,
-            unquote(name)(c5)::6,
-            unquote(name)(c6)::6,
-            unquote(name)(c7)::6,
-            unquote(name)(c8)::6
+            unquote(decode_name)(c1)::6,
+            unquote(decode_name)(c2)::6,
+            unquote(decode_name)(c3)::6,
+            unquote(decode_name)(c4)::6,
+            unquote(decode_name)(c5)::6,
+            unquote(decode_name)(c6)::6,
+            unquote(decode_name)(c7)::6,
+            unquote(decode_name)(c8)::6
           >>
 
         <<c1::8, c2::8>> when not pad? ->
-          <<main::bits, unquote(name)(c1)::6, bsr(unquote(name)(c2), 4)::2>>
+          <<main::bits, unquote(decode_name)(c1)::6, bsr(unquote(decode_name)(c2), 4)::2>>
 
         <<c1::8, c2::8, c3::8>> when not pad? ->
-          <<main::bits, unquote(name)(c1)::6, unquote(name)(c2)::6, bsr(unquote(name)(c3), 2)::4>>
+          <<main::bits, unquote(decode_name)(c1)::6, unquote(decode_name)(c2)::6,
+            bsr(unquote(decode_name)(c3), 2)::4>>
 
         <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8>> when not pad? ->
           <<
             main::bits,
-            unquote(name)(c1)::6,
-            unquote(name)(c2)::6,
-            unquote(name)(c3)::6,
-            unquote(name)(c4)::6,
-            unquote(name)(c5)::6,
-            bsr(unquote(name)(c6), 4)::2
+            unquote(decode_name)(c1)::6,
+            unquote(decode_name)(c2)::6,
+            unquote(decode_name)(c3)::6,
+            unquote(decode_name)(c4)::6,
+            unquote(decode_name)(c5)::6,
+            bsr(unquote(decode_name)(c6), 4)::2
           >>
 
         <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8>> when not pad? ->
           <<
             main::bits,
-            unquote(name)(c1)::6,
-            unquote(name)(c2)::6,
-            unquote(name)(c3)::6,
-            unquote(name)(c4)::6,
-            unquote(name)(c5)::6,
-            unquote(name)(c6)::6,
-            bsr(unquote(name)(c7), 2)::4
+            unquote(decode_name)(c1)::6,
+            unquote(decode_name)(c2)::6,
+            unquote(decode_name)(c3)::6,
+            unquote(decode_name)(c4)::6,
+            unquote(decode_name)(c5)::6,
+            unquote(decode_name)(c6)::6,
+            bsr(unquote(decode_name)(c7), 2)::4
           >>
 
         _ ->
@@ -983,6 +1235,45 @@ defmodule Base do
     end
   end
 
+  @doc """
+  Checks if a base 32 encoded string is valid.
+
+  > #### When to use this {: .tip}
+  >
+  > Use this function when you just need to *validate* that a string is
+  > valid base 32 data, without actually producing a decoded output string.
+  > This function is both more performant and memory efficient than using
+  > `decode32/2`, checking that the result is `{:ok, ...}`, and then
+  > discarding the decoded binary.
+
+  ## Options
+
+  Accepts the same options as `decode32/2`.
+
+  ## Examples
+
+      iex> Base.valid32?("MZXW6YTBOI======")
+      true
+
+      iex> Base.valid32?("mzxw6ytboi======", case: :lower)
+      true
+
+      iex> Base.valid32?("zzz")
+      false
+
+  """
+  @doc since: "1.19.0"
+  @spec valid32?(binary, case: decode_case, padding: boolean) :: boolean()
+  def valid32?(string, opts \\ []) when is_binary(string) do
+    pad? = Keyword.get(opts, :padding, true)
+
+    case Keyword.get(opts, :case, :upper) do
+      :upper -> validate32upper?(string, pad?)
+      :lower -> validate32lower?(string, pad?)
+      :mixed -> validate32mixed?(string, pad?)
+    end
+  end
+
   @doc """
   Decodes a base 32 encoded string with extended hexadecimal alphabet
   into a binary string.
@@ -1078,6 +1369,45 @@ defmodule Base do
     end
   end
 
+  @doc """
+  Checks if a base 32 encoded string with extended hexadecimal alphabet is valid.
+
+  > #### When to use this {: .tip}
+  >
+  > Use this function when you just need to *validate* that a string is
+  > valid (extended hexadecimal) base 32 data, without actually producing
+  > a decoded output string. This function is both more performant and
+  > memory efficient than using `hex_decode32/2`, checking that the result
+  > is `{:ok, ...}`, and then discarding the decoded binary.
+
+  ## Options
+
+  Accepts the same options as `hex_decode32/2`.
+
+  ## Examples
+
+      iex> Base.hex_valid32?("CPNMUOJ1E8======")
+      true
+
+      iex> Base.hex_valid32?("cpnmuoj1e8======", case: :lower)
+      true
+
+      iex> Base.hex_valid32?("zzz", padding: false)
+      false
+
+  """
+  @doc since: "1.19.0"
+  @spec hex_valid32?(binary, case: decode_case, padding: boolean) :: boolean
+  def hex_valid32?(string, opts \\ []) when is_binary(string) do
+    pad? = Keyword.get(opts, :padding, true)
+
+    case Keyword.get(opts, :case, :upper) do
+      :upper -> validate32hexupper?(string, pad?)
+      :lower -> validate32hexlower?(string, pad?)
+      :mixed -> validate32hexmixed?(string, pad?)
+    end
+  end
+
   upper = Enum.with_index(b32_alphabet)
   hexupper = Enum.with_index(b32hex_alphabet)
 
@@ -1089,120 +1419,223 @@ defmodule Base do
         hexlower: to_lower_dec.(hexupper),
         hexmixed: to_mixed_dec.(hexupper)
       ] do
-    name = :"decode32#{base}!"
+    decode_name = :"decode32#{base}!"
+    validate_name = :"validate32#{base}?"
+    validate_main_name = :"validate_main32#{validate_name}?"
+    valid_char_name = :"valid_char32#{base}?"
     {min, decoded} = to_decode_list.(alphabet)
 
-    defp unquote(name)(char) do
-      try do
-        elem({unquote_splicing(decoded)}, char - unquote(min))
-      rescue
-        _ -> bad_character!(char)
-      else
-        nil -> bad_character!(char)
-        char -> char
+    defp unquote(validate_main_name)(<<>>), do: true
+
+    defp unquote(validate_main_name)(
+           <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8, c8::8, rest::binary>>
+         ) do
+      unquote(valid_char_name)(c1) and
+        unquote(valid_char_name)(c2) and
+        unquote(valid_char_name)(c3) and
+        unquote(valid_char_name)(c4) and
+        unquote(valid_char_name)(c5) and
+        unquote(valid_char_name)(c6) and
+        unquote(valid_char_name)(c7) and
+        unquote(valid_char_name)(c8) and
+        unquote(validate_main_name)(rest)
+    end
+
+    defp unquote(validate_name)(<<>>, _pad?), do: true
+
+    defp unquote(validate_name)(string, pad?) do
+      segs = div(byte_size(string) + 7, 8) - 1
+      <<main::size(^segs)-binary-unit(64), rest::binary>> = string
+      main_valid? = unquote(validate_main_name)(main)
+
+      case rest do
+        _ when not main_valid? ->
+          false
+
+        <<c1::8, c2::8, ?=, ?=, ?=, ?=, ?=, ?=>> ->
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2)
+
+        <<c1::8, c2::8, c3::8, c4::8, ?=, ?=, ?=, ?=>> ->
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3) and
+            unquote(valid_char_name)(c4)
+
+        <<c1::8, c2::8, c3::8, c4::8, c5::8, ?=, ?=, ?=>> ->
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3) and
+            unquote(valid_char_name)(c4) and
+            unquote(valid_char_name)(c5)
+
+        <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8, ?=>> ->
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3) and
+            unquote(valid_char_name)(c4) and
+            unquote(valid_char_name)(c5) and
+            unquote(valid_char_name)(c6) and
+            unquote(valid_char_name)(c7)
+
+        <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8, c8::8>> ->
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3) and
+            unquote(valid_char_name)(c4) and
+            unquote(valid_char_name)(c5) and
+            unquote(valid_char_name)(c6) and
+            unquote(valid_char_name)(c7) and
+            unquote(valid_char_name)(c8)
+
+        <<c1::8, c2::8>> when not pad? ->
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2)
+
+        <<c1::8, c2::8, c3::8, c4::8>> when not pad? ->
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3) and
+            unquote(valid_char_name)(c4)
+
+        <<c1::8, c2::8, c3::8, c4::8, c5::8>> when not pad? ->
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3) and
+            unquote(valid_char_name)(c4) and
+            unquote(valid_char_name)(c5)
+
+        <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8>> when not pad? ->
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3) and
+            unquote(valid_char_name)(c4) and
+            unquote(valid_char_name)(c5) and
+            unquote(valid_char_name)(c6) and
+            unquote(valid_char_name)(c7)
+
+        _ ->
+          false
       end
     end
 
-    defp unquote(name)(<<>>, _), do: <<>>
+    @compile {:inline, [{valid_char_name, 1}]}
+    defp unquote(valid_char_name)(char)
+         when elem({unquote_splicing(decoded)}, char - unquote(min)) != nil,
+         do: true
 
-    defp unquote(name)(string, pad?) do
+    defp unquote(valid_char_name)(_char), do: false
+
+    defp unquote(decode_name)(char) do
+      index = char - unquote(min)
+
+      cond do
+        index not in 0..unquote(length(decoded) - 1) -> bad_character!(char)
+        new_char = elem({unquote_splicing(decoded)}, index) -> new_char
+        true -> bad_character!(char)
+      end
+    end
+
+    defp unquote(decode_name)(<<>>, _), do: <<>>
+
+    defp unquote(decode_name)(string, pad?) do
       segs = div(byte_size(string) + 7, 8) - 1
       <<main::size(^segs)-binary-unit(64), rest::binary>> = string
 
       main =
         for <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8, c8::8 <- main>>, into: <<>> do
           <<
-            unquote(name)(c1)::5,
-            unquote(name)(c2)::5,
-            unquote(name)(c3)::5,
-            unquote(name)(c4)::5,
-            unquote(name)(c5)::5,
-            unquote(name)(c6)::5,
-            unquote(name)(c7)::5,
-            unquote(name)(c8)::5
+            unquote(decode_name)(c1)::5,
+            unquote(decode_name)(c2)::5,
+            unquote(decode_name)(c3)::5,
+            unquote(decode_name)(c4)::5,
+            unquote(decode_name)(c5)::5,
+            unquote(decode_name)(c6)::5,
+            unquote(decode_name)(c7)::5,
+            unquote(decode_name)(c8)::5
           >>
         end
 
       case rest do
         <<c1::8, c2::8, ?=, ?=, ?=, ?=, ?=, ?=>> ->
-          <<main::bits, unquote(name)(c1)::5, bsr(unquote(name)(c2), 2)::3>>
+          <<main::bits, unquote(decode_name)(c1)::5, bsr(unquote(decode_name)(c2), 2)::3>>
 
         <<c1::8, c2::8, c3::8, c4::8, ?=, ?=, ?=, ?=>> ->
           <<
             main::bits,
-            unquote(name)(c1)::5,
-            unquote(name)(c2)::5,
-            unquote(name)(c3)::5,
-            bsr(unquote(name)(c4), 4)::1
+            unquote(decode_name)(c1)::5,
+            unquote(decode_name)(c2)::5,
+            unquote(decode_name)(c3)::5,
+            bsr(unquote(decode_name)(c4), 4)::1
           >>
 
         <<c1::8, c2::8, c3::8, c4::8, c5::8, ?=, ?=, ?=>> ->
           <<
             main::bits,
-            unquote(name)(c1)::5,
-            unquote(name)(c2)::5,
-            unquote(name)(c3)::5,
-            unquote(name)(c4)::5,
-            bsr(unquote(name)(c5), 1)::4
+            unquote(decode_name)(c1)::5,
+            unquote(decode_name)(c2)::5,
+            unquote(decode_name)(c3)::5,
+            unquote(decode_name)(c4)::5,
+            bsr(unquote(decode_name)(c5), 1)::4
           >>
 
         <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8, ?=>> ->
           <<
             main::bits,
-            unquote(name)(c1)::5,
-            unquote(name)(c2)::5,
-            unquote(name)(c3)::5,
-            unquote(name)(c4)::5,
-            unquote(name)(c5)::5,
-            unquote(name)(c6)::5,
-            bsr(unquote(name)(c7), 3)::2
+            unquote(decode_name)(c1)::5,
+            unquote(decode_name)(c2)::5,
+            unquote(decode_name)(c3)::5,
+            unquote(decode_name)(c4)::5,
+            unquote(decode_name)(c5)::5,
+            unquote(decode_name)(c6)::5,
+            bsr(unquote(decode_name)(c7), 3)::2
           >>
 
         <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8, c8::8>> ->
           <<
             main::bits,
-            unquote(name)(c1)::5,
-            unquote(name)(c2)::5,
-            unquote(name)(c3)::5,
-            unquote(name)(c4)::5,
-            unquote(name)(c5)::5,
-            unquote(name)(c6)::5,
-            unquote(name)(c7)::5,
-            unquote(name)(c8)::5
+            unquote(decode_name)(c1)::5,
+            unquote(decode_name)(c2)::5,
+            unquote(decode_name)(c3)::5,
+            unquote(decode_name)(c4)::5,
+            unquote(decode_name)(c5)::5,
+            unquote(decode_name)(c6)::5,
+            unquote(decode_name)(c7)::5,
+            unquote(decode_name)(c8)::5
           >>
 
         <<c1::8, c2::8>> when not pad? ->
-          <<main::bits, unquote(name)(c1)::5, bsr(unquote(name)(c2), 2)::3>>
+          <<main::bits, unquote(decode_name)(c1)::5, bsr(unquote(decode_name)(c2), 2)::3>>
 
         <<c1::8, c2::8, c3::8, c4::8>> when not pad? ->
           <<
             main::bits,
-            unquote(name)(c1)::5,
-            unquote(name)(c2)::5,
-            unquote(name)(c3)::5,
-            bsr(unquote(name)(c4), 4)::1
+            unquote(decode_name)(c1)::5,
+            unquote(decode_name)(c2)::5,
+            unquote(decode_name)(c3)::5,
+            bsr(unquote(decode_name)(c4), 4)::1
           >>
 
         <<c1::8, c2::8, c3::8, c4::8, c5::8>> when not pad? ->
           <<
             main::bits,
-            unquote(name)(c1)::5,
-            unquote(name)(c2)::5,
-            unquote(name)(c3)::5,
-            unquote(name)(c4)::5,
-            bsr(unquote(name)(c5), 1)::4
+            unquote(decode_name)(c1)::5,
+            unquote(decode_name)(c2)::5,
+            unquote(decode_name)(c3)::5,
+            unquote(decode_name)(c4)::5,
+            bsr(unquote(decode_name)(c5), 1)::4
           >>
 
         <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8>> when not pad? ->
           <<
             main::bits,
-            unquote(name)(c1)::5,
-            unquote(name)(c2)::5,
-            unquote(name)(c3)::5,
-            unquote(name)(c4)::5,
-            unquote(name)(c5)::5,
-            unquote(name)(c6)::5,
-            bsr(unquote(name)(c7), 3)::2
+            unquote(decode_name)(c1)::5,
+            unquote(decode_name)(c2)::5,
+            unquote(decode_name)(c3)::5,
+            unquote(decode_name)(c4)::5,
+            unquote(decode_name)(c5)::5,
+            unquote(decode_name)(c6)::5,
+            bsr(unquote(decode_name)(c7), 3)::2
           >>
 
         _ ->

lib/elixir/lib/behaviour.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Behaviour do
   @moduledoc """
   Mechanism for handling behaviours.

lib/elixir/lib/bitwise.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Bitwise do
   @moduledoc """
   A set of functions that perform calculations on bits.

lib/elixir/lib/calendar.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Calendar do
   @moduledoc """
   This module defines the responsibilities for working with
@@ -54,9 +58,20 @@ defmodule Calendar do
   @typedoc """
   Microseconds with stored precision.
 
-  The precision represents the number of digits that must be used when
+  `value` always represents the total value in microseconds.
+
+  The `precision` represents the number of digits that must be used when
   representing the microseconds to external format. If the precision is `0`,
-  it means microseconds must be skipped.
+  it means microseconds must be skipped. If the precision is `6`, it means
+  that `value` represents exactly the number of microseconds to be used.
+
+  ## Examples
+
+    * `{0, 0}` means no microseconds.
+    * `{1, 6}` means 1µs.
+    * `{1000, 6}` means 1000µs (which is 1ms but measured at the microsecond precision).
+    * `{1000, 3}` means 1ms (which is measured at the millisecond precision).
+
   """
   @type microsecond :: {value :: non_neg_integer, precision :: non_neg_integer}
 
@@ -147,6 +162,22 @@ defmodule Calendar do
   """
   @type time_zone_database :: module()
 
+  @typedoc """
+  Options for formatting dates and times with `strftime/3`.
+  """
+  @type strftime_opts :: [
+          preferred_datetime: String.t(),
+          preferred_date: String.t(),
+          preferred_time: String.t(),
+          am_pm_names: (:am | :pm -> String.t()) | (:am | :pm, map() -> String.t()),
+          month_names: (pos_integer() -> String.t()) | (pos_integer(), map() -> String.t()),
+          abbreviated_month_names:
+            (pos_integer() -> String.t()) | (pos_integer(), map() -> String.t()),
+          day_of_week_names: (pos_integer() -> String.t()) | (pos_integer(), map() -> String.t()),
+          abbreviated_day_of_week_names:
+            (pos_integer() -> String.t()) | (pos_integer(), map() -> String.t())
+        ]
+
   @doc """
   Returns how many days there are in the given month of the given year.
   """
@@ -172,6 +203,15 @@ defmodule Calendar do
   `starting_on` represents the starting day of the week. All
   calendars must support at least the `:default` value. They may
   also support other values representing their days of the week.
+
+  The value of `day_of_week` is an ordinal number meaning that a
+  value of `1` is defined to mean "first day of the week". It is
+  specifically not defined to mean `1` is `Monday`.
+
+  It is a requirement that `first_day_of_week` is less than `last_day_of_week`
+  and that `day_of_week` must be within that range. Therefore it can be said
+  that `day_of_week in first_day_of_week..last_day_of_week//1` must be
+  `true` for all values of `day_of_week`.
   """
   @callback day_of_week(year, month, day, starting_on :: :default | atom) ::
               {day_of_week(), first_day_of_week :: non_neg_integer(),
@@ -452,25 +492,30 @@ defmodule Calendar do
       it can't contain the `%X` format and defaults to `"%H:%M:%S"`
       if the option is not received
 
-    * `:am_pm_names` - a function that receives either `:am` or `:pm` and returns
+    * `:am_pm_names` - a function that receives either `:am` or `:pm`
+      (and also the datetime if the function is arity/2) and returns
       the name of the period of the day, if the option is not received it defaults
       to a function that returns `"am"` and `"pm"`, respectively
 
-    *  `:month_names` - a function that receives a number and returns the name of
+    *  `:month_names` - a function that receives a number (and also the
+      datetime if the function is arity/2) and returns the name of
       the corresponding month, if the option is not received it defaults to a
       function that returns the month names in English
 
-    * `:abbreviated_month_names` - a function that receives a number and returns the
+    * `:abbreviated_month_names` - a function that receives a number (and also
+      the datetime if the function is arity/2) and returns the
       abbreviated name of the corresponding month, if the option is not received it
       defaults to a function that returns the abbreviated month names in English
 
-    * `:day_of_week_names` - a function that receives a number and returns the name of
+    * `:day_of_week_names` - a function that receives a number and (and also the
+      datetime if the function is arity/2) returns the name of
       the corresponding day of week, if the option is not received it defaults to a
       function that returns the day of week names in English
 
-    * `:abbreviated_day_of_week_names` - a function that receives a number and returns
-      the abbreviated name of the corresponding day of week, if the option is not received
-      it defaults to a function that returns the abbreviated day of week names in English
+    * `:abbreviated_day_of_week_names` - a function that receives a number (and also
+      the datetime if the function is arity/2) and returns the abbreviated name of
+      the corresponding day of week, if the option is not received it defaults to a
+      function that returns the abbreviated day of week names in English
 
   ## Formatting syntax
 
@@ -504,7 +549,7 @@ defmodule Calendar do
   B      | Full month name                                                         | January
   c      | Preferred date+time representation                                      | 2018-10-17 12:34:56
   d      | Day of the month                                                        | 01, 31
-  f      | Microseconds *(does not support width and padding modifiers)*           | 000000, 999999, 0123
+  f      | Microseconds (uses its precision for width and padding)                 | 000000, 999999, 0123
   H      | Hour using a 24-hour clock                                              | 00, 23
   I      | Hour using a 12-hour clock                                              | 01, 12
   j      | Day of the year                                                         | 001, 366
@@ -526,6 +571,12 @@ defmodule Calendar do
 
   Any other character will be interpreted as an invalid format and raise an error.
 
+  ### `%f` Microseconds
+
+  `%f` does not support width and padding modifiers.  It will be formatted by truncating
+  the microseconds to the precision of the `microseconds` field of the struct, with a
+  minimum precision of 1.
+
   ## Examples
 
   Without user options:
@@ -569,9 +620,20 @@ defmodule Calendar do
       ...>)
       "серпень"
 
+   Microsecond formatting:
+
+      iex> Calendar.strftime(~U[2019-08-26 13:52:06Z], "%y-%m-%d %H:%M:%S.%f")
+      "19-08-26 13:52:06.0"
+
+      iex> Calendar.strftime(~U[2019-08-26 13:52:06.048Z], "%y-%m-%d %H:%M:%S.%f")
+      "19-08-26 13:52:06.048"
+
+      iex> Calendar.strftime(~U[2019-08-26 13:52:06.048531Z], "%y-%m-%d %H:%M:%S.%f")
+      "19-08-26 13:52:06.048531"
+
   """
   @doc since: "1.11.0"
-  @spec strftime(map(), String.t(), keyword()) :: String.t()
+  @spec strftime(map(), String.t(), strftime_opts()) :: String.t()
   def strftime(date_or_time_or_datetime, string_format, user_options \\ [])
       when is_map(date_or_time_or_datetime) and is_binary(string_format) do
     parse(
@@ -624,12 +686,12 @@ defmodule Calendar do
     format_modifiers(rest, width, pad, datetime, format_options, acc)
   end
 
-  defp am_pm(hour, format_options) when hour > 11 do
-    format_options.am_pm_names.(:pm)
+  defp am_pm(hour, format_options, datetime) when hour > 11 do
+    apply_format(:pm, format_options.am_pm_names, datetime)
   end
 
-  defp am_pm(hour, format_options) when hour <= 11 do
-    format_options.am_pm_names.(:am)
+  defp am_pm(hour, format_options, datetime) when hour <= 11 do
+    apply_format(:am, format_options.am_pm_names, datetime)
   end
 
   defp default_pad(format) when format in ~c"aAbBpPZ", do: ?\s
@@ -650,7 +712,7 @@ defmodule Calendar do
     result =
       datetime
       |> Date.day_of_week()
-      |> format_options.abbreviated_day_of_week_names.()
+      |> apply_format(format_options.abbreviated_day_of_week_names, datetime)
       |> pad_leading(width, pad)
 
     parse(rest, datetime, format_options, [result | acc])
@@ -661,7 +723,7 @@ defmodule Calendar do
     result =
       datetime
       |> Date.day_of_week()
-      |> format_options.day_of_week_names.()
+      |> apply_format(format_options.day_of_week_names, datetime)
       |> pad_leading(width, pad)
 
     parse(rest, datetime, format_options, [result | acc])
@@ -671,7 +733,7 @@ defmodule Calendar do
   defp format_modifiers("b" <> rest, width, pad, datetime, format_options, acc) do
     result =
       datetime.month
-      |> format_options.abbreviated_month_names.()
+      |> apply_format(format_options.abbreviated_month_names, datetime)
       |> pad_leading(width, pad)
 
     parse(rest, datetime, format_options, [result | acc])
@@ -679,7 +741,10 @@ defmodule Calendar do
 
   # Full month name
   defp format_modifiers("B" <> rest, width, pad, datetime, format_options, acc) do
-    result = datetime.month |> format_options.month_names.() |> pad_leading(width, pad)
+    result =
+      datetime.month
+      |> apply_format(format_options.month_names, datetime)
+      |> pad_leading(width, pad)
 
     parse(rest, datetime, format_options, [result | acc])
   end
@@ -757,7 +822,11 @@ defmodule Calendar do
 
   # "AM" or "PM" (noon is "PM", midnight as "AM")
   defp format_modifiers("p" <> rest, width, pad, datetime, format_options, acc) do
-    result = datetime.hour |> am_pm(format_options) |> String.upcase() |> pad_leading(width, pad)
+    result =
+      datetime.hour
+      |> am_pm(format_options, datetime)
+      |> String.upcase()
+      |> pad_leading(width, pad)
 
     parse(rest, datetime, format_options, [result | acc])
   end
@@ -766,7 +835,7 @@ defmodule Calendar do
   defp format_modifiers("P" <> rest, width, pad, datetime, format_options, acc) do
     result =
       datetime.hour
-      |> am_pm(format_options)
+      |> am_pm(format_options, datetime)
       |> String.downcase()
       |> pad_leading(width, pad)
 
@@ -932,6 +1001,18 @@ defmodule Calendar do
   defp do_pad_leading(count, padding, acc),
     do: do_pad_leading(count - 1, padding, [padding | acc])
 
+  defp apply_format(term, formatter, _datetime) when is_function(formatter, 1) do
+    formatter.(term)
+  end
+
+  defp apply_format(term, formatter, datetime) when is_function(formatter, 2) do
+    formatter.(term, datetime)
+  end
+
+  defp apply_format(_term, formatter, _datetime) do
+    raise ArgumentError, "formatter functions must be of arity 1 or 2, got: #{inspect(formatter)}"
+  end
+
   defp options(user_options) do
     default_options = %{
       preferred_date: "%Y-%m-%d",

lib/elixir/lib/calendar/date.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Date do
   @moduledoc """
   A Date struct and functions.
@@ -31,11 +35,12 @@ defmodule Date do
 
   Comparisons in Elixir using `==/2`, `>/2`, `</2` and similar are structural
   and based on the `Date` struct fields. For proper comparison between
-  dates, use the `compare/2` function. The existence of the `compare/2`
-  function in this module also allows using `Enum.min/2` and `Enum.max/2`
-  functions to get the minimum and maximum date of an `Enum`. For example:
+  dates, use the `compare/2`, `after?/2` and `before?/2` functions.
+  The existence of the `compare/2` function in this module also allows
+  using `Enum.min/2` and `Enum.max/2` functions to get the minimum and
+  maximum date of an `Enum`. For example:
 
-      iex>  Enum.min([~D[2017-03-31], ~D[2017-04-01]], Date)
+      iex> Enum.min([~D[2017-03-31], ~D[2017-04-01]], Date)
       ~D[2017-03-31]
 
   ## Using epochs
@@ -188,9 +193,8 @@ defmodule Date do
   end
 
   def utc_today(calendar) do
-    calendar
-    |> DateTime.utc_now()
-    |> DateTime.to_date()
+    %{year: year, month: month, day: day} = DateTime.utc_now(calendar)
+    %Date{year: year, month: month, day: day, calendar: calendar}
   end
 
   @doc """
@@ -317,7 +321,7 @@ defmodule Date do
   @doc """
   Converts the given date to a string according to its calendar.
 
-  ### Examples
+  ## Examples
 
       iex> Date.to_string(~D[2000-02-28])
       "2000-02-28"
@@ -395,7 +399,7 @@ defmodule Date do
   or other calendars in which the days also start at midnight.
   Attempting to convert dates from other calendars will raise an `ArgumentError`.
 
-  ### Examples
+  ## Examples
 
       iex> Date.to_iso8601(~D[2000-02-28])
       "2000-02-28"
@@ -629,7 +633,7 @@ defmodule Date do
   ## Examples
 
   Imagine someone implements `Calendar.Holocene`, a calendar based on the
-  Gregorian calendar that adds exactly 10,000 years to the current Gregorian
+  Gregorian calendar that adds exactly 10 000 years to the current Gregorian
   year:
 
       iex> Date.convert(~D[2000-01-01], Calendar.Holocene)
@@ -663,7 +667,7 @@ defmodule Date do
   ## Examples
 
   Imagine someone implements `Calendar.Holocene`, a calendar based on the
-  Gregorian calendar that adds exactly 10,000 years to the current Gregorian
+  Gregorian calendar that adds exactly 10 000 years to the current Gregorian
   year:
 
       iex> Date.convert!(~D[2000-01-01], Calendar.Holocene)
@@ -687,10 +691,15 @@ defmodule Date do
   @doc """
   Adds the number of days to the given `date`.
 
-  The days are counted as Gregorian days. The date is returned in the same
-  calendar as it was given in.
+  > #### Prefer `shift/2` {: .info}
+  >
+  > Prefer `shift/2` over `add/2`, as it offers a more ergonomic API.
+  >
+  > `add/2` always considers a day to be measured according to the
+  > `Calendar.ISO`.
 
-  To shift a date by a `Duration` and according to its underlying calendar, use `Date.shift/2`.
+  The days are counted as Gregorian days, independent of the underlying
+  calendar. The date is returned in the same calendar as it was given in.
 
   ## Examples
 
@@ -852,7 +861,7 @@ defmodule Date do
   end
 
   @doc """
-  Calculates the day of the week of a given `date`.
+  Calculates the ordinal day of the week of a given `date`.
 
   Returns the day of the week as an integer. For the ISO 8601
   calendar (the default), it is an integer from 1 to 7, where
@@ -861,10 +870,19 @@ defmodule Date do
   An optional `starting_on` value may be supplied, which
   configures the weekday the week starts on. The default value
   for it is `:default`, which translates to `:monday` for the
-  built-in ISO calendar. Any other weekday may be given to.
+  built-in ISO 8601 calendar. Any other weekday may be used for
+  `starting_on`, in such cases, that weekday will be considered the first
+  day of the week, and therefore it will be assigned the ordinal number 1.
+
+  The other calendars, the value returned is an ordinal day of week.
+  For example, `1` may mean "first day of the week" and `7` is
+  defined to mean "seventh day of the week". Custom calendars may
+  also accept their own variations of the `starting_on` parameter
+  with their own meaning.
 
   ## Examples
 
+      # 2016-10-31 is a Monday and by default Monday is the first day of the week
       iex> Date.day_of_week(~D[2016-10-31])
       1
       iex> Date.day_of_week(~D[2016-11-01])
@@ -874,6 +892,7 @@ defmodule Date do
       iex> Date.day_of_week(~D[-0015-10-30])
       3
 
+      # 2016-10-31 is a Monday but, as we start the week on Sunday, now it returns 2
       iex> Date.day_of_week(~D[2016-10-31], :sunday)
       2
       iex> Date.day_of_week(~D[2016-11-01], :sunday)

lib/elixir/lib/calendar/date_range.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Date.Range do
   @moduledoc """
   Returns an inclusive range between dates.
@@ -91,7 +95,7 @@ defmodule Date.Range do
       [date_from_iso_days(current, calendar)]
     end
 
-    defp slice(current, step, remaining, calendar) do
+    defp slice(current, step, remaining, calendar) when remaining > 1 do
       [
         date_from_iso_days(current, calendar)
         | slice(current + step, step, remaining - 1, calendar)
@@ -167,8 +171,12 @@ defmodule Date.Range do
          when step < 0 and first_days < last_days,
          do: 0
 
-    defp size(%Date.Range{first_in_iso_days: first_days, last_in_iso_days: last_days, step: step}),
-      do: abs(div(last_days - first_days, step)) + 1
+    defp size(%Date.Range{
+           first_in_iso_days: first_days,
+           last_in_iso_days: last_days,
+           step: step
+         }),
+         do: abs(div(last_days - first_days, step)) + 1
 
     # TODO: Remove me on v2.0
     defp size(

lib/elixir/lib/calendar/datetime.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule DateTime do
   @moduledoc """
   A datetime implementation with a time zone.
@@ -13,8 +17,8 @@ defmodule DateTime do
 
   Remember, comparisons in Elixir using `==/2`, `>/2`, `</2` and friends
   are structural and based on the DateTime struct fields. For proper
-  comparison between datetimes, use the `compare/2` function. The
-  existence of the `compare/2` function in this module also allows
+  comparison between datetimes, use the `compare/2`, `after?/2` and `before?/2` functions.
+  The existence of the `compare/2` function in this module also allows
   using `Enum.min/2` and `Enum.max/2` functions to get the minimum and
   maximum datetime of an `Enum`. For example:
 
@@ -379,13 +383,12 @@ defmodule DateTime do
   @doc """
   Converts the given Unix time to `DateTime`.
 
-  The integer can be given in different unit
-  according to `System.convert_time_unit/3` and it will
-  be converted to microseconds internally. Up to
-  253402300799 seconds is supported.
+  The integer can be given in different unit, according to `System.convert_time_unit/3`,
+  and it will be converted to microseconds internally, which is the maximum precision
+  supported by `DateTime`. In other words, any precision higher than microseconds will
+  lead to truncation.
 
-  Unix times are always in UTC and therefore the DateTime
-  will be returned in UTC.
+  Unix times are always in UTC. Therefore the DateTime will be returned in UTC.
 
   ## Examples
 
@@ -881,8 +884,10 @@ defmodule DateTime do
   The `datetime` is expected to be using the ISO calendar
   with a year greater than or equal to 0.
 
-  It will return the integer with the given unit,
-  according to `System.convert_time_unit/3`.
+  It will return the integer with the given unit, according
+  to `System.convert_time_unit/3`. If the given unit is different
+  than microseconds, the returned value will be either truncated
+  or padded accordingly.
 
   ## Examples
 
@@ -1041,7 +1046,7 @@ defmodule DateTime do
   its abbreviation, which means information is lost when converting to such
   format.
 
-  ### Examples
+  ## Examples
 
       iex> dt = %DateTime{year: 2000, month: 2, day: 29, zone_abbr: "CET",
       ...>                hour: 23, minute: 0, second: 7, microsecond: {0, 0},
@@ -1091,8 +1096,21 @@ defmodule DateTime do
   @spec to_iso8601(Calendar.datetime(), :basic | :extended, nil | integer()) :: String.t()
   def to_iso8601(datetime, format \\ :extended, offset \\ nil)
 
-  def to_iso8601(%{calendar: Calendar.ISO} = datetime, format, nil)
+  def to_iso8601(%{calendar: Calendar.ISO} = datetime, format, offset)
       when format in [:extended, :basic] do
+    datetime
+    |> to_iso8601_iodata(format, offset)
+    |> IO.iodata_to_binary()
+  end
+
+  def to_iso8601(%{calendar: _} = datetime, format, offset)
+      when format in [:extended, :basic] do
+    datetime
+    |> convert!(Calendar.ISO)
+    |> to_iso8601(format, offset)
+  end
+
+  defp to_iso8601_iodata(datetime, format, nil) do
     %{
       year: year,
       month: month,
@@ -1106,35 +1124,51 @@ defmodule DateTime do
       std_offset: std_offset
     } = datetime
 
-    datetime_to_string(year, month, day, hour, minute, second, microsecond, format) <>
-      Calendar.ISO.offset_to_string(utc_offset, std_offset, time_zone, format)
+    [
+      datetime_to_iodata(year, month, day, hour, minute, second, microsecond, format),
+      Calendar.ISO.offset_to_iodata(utc_offset, std_offset, time_zone, format)
+    ]
   end
 
-  def to_iso8601(
-        %{calendar: Calendar.ISO, microsecond: {_, precision}, time_zone: "Etc/UTC"} = datetime,
-        format,
-        0
-      )
-      when format in [:extended, :basic] do
+  defp to_iso8601_iodata(
+         %{microsecond: {_, precision}, time_zone: "Etc/UTC"} = datetime,
+         format,
+         0
+       ) do
     {year, month, day, hour, minute, second, {microsecond, _}} = shift_by_offset(datetime, 0)
 
-    datetime_to_string(year, month, day, hour, minute, second, {microsecond, precision}, format) <>
-      "Z"
+    [
+      datetime_to_iodata(
+        year,
+        month,
+        day,
+        hour,
+        minute,
+        second,
+        {microsecond, precision},
+        format
+      ),
+      ?Z
+    ]
   end
 
-  def to_iso8601(%{calendar: Calendar.ISO} = datetime, format, offset)
-      when format in [:extended, :basic] do
+  defp to_iso8601_iodata(datetime, format, offset) do
     {_, precision} = datetime.microsecond
     {year, month, day, hour, minute, second, {microsecond, _}} = shift_by_offset(datetime, offset)
 
-    datetime_to_string(year, month, day, hour, minute, second, {microsecond, precision}, format) <>
-      Calendar.ISO.offset_to_string(offset, 0, nil, format)
-  end
-
-  def to_iso8601(%{calendar: _} = datetime, format, offset) when format in [:extended, :basic] do
-    datetime
-    |> convert!(Calendar.ISO)
-    |> to_iso8601(format, offset)
+    [
+      datetime_to_iodata(
+        year,
+        month,
+        day,
+        hour,
+        minute,
+        second,
+        {microsecond, precision},
+        format
+      ),
+      Calendar.ISO.offset_to_iodata(offset, 0, nil, format)
+    ]
   end
 
   defp shift_by_offset(%{calendar: calendar} = datetime, offset) do
@@ -1147,10 +1181,12 @@ defmodule DateTime do
     |> calendar.naive_datetime_from_iso_days()
   end
 
-  defp datetime_to_string(year, month, day, hour, minute, second, microsecond, format) do
-    Calendar.ISO.date_to_string(year, month, day, format) <>
-      "T" <>
-      Calendar.ISO.time_to_string(hour, minute, second, microsecond, format)
+  defp datetime_to_iodata(year, month, day, hour, minute, second, microsecond, format) do
+    [
+      Calendar.ISO.date_to_iodata(year, month, day, format),
+      ?T,
+      Calendar.ISO.time_to_iodata(hour, minute, second, microsecond, format)
+    ]
   end
 
   @doc """
@@ -1354,7 +1390,7 @@ defmodule DateTime do
   custom (but relatively common) representation which appends the time
   zone abbreviation and full name to the datetime.
 
-  ### Examples
+  ## Examples
 
       iex> dt = %DateTime{year: 2000, month: 2, day: 29, zone_abbr: "CET",
       ...>                hour: 23, minute: 0, second: 7, microsecond: {0, 0},
@@ -1563,42 +1599,56 @@ defmodule DateTime do
     end
 
     naive_diff =
-      (datetime1 |> to_iso_days() |> Calendar.ISO.iso_days_to_unit(unit)) -
-        (datetime2 |> to_iso_days() |> Calendar.ISO.iso_days_to_unit(unit))
+      (datetime1 |> to_iso_days() |> Calendar.ISO.iso_days_to_unit(:microsecond)) -
+        (datetime2 |> to_iso_days() |> Calendar.ISO.iso_days_to_unit(:microsecond))
 
     offset_diff = utc_offset2 + std_offset2 - (utc_offset1 + std_offset1)
-    naive_diff + System.convert_time_unit(offset_diff, :second, unit)
+
+    System.convert_time_unit(naive_diff, :microsecond, unit) +
+      System.convert_time_unit(offset_diff, :second, unit)
   end
 
   @doc """
   Adds a specified amount of time to a `DateTime`.
 
+  > #### Prefer `shift/2` {: .info}
+  >
+  > Prefer `shift/2` over `add/3`, as it offers a more ergonomic API.
+  >
+  > `add/3` provides a lower-level API which only supports fixed units
+  > such as `:hour` and `:second`, but not `:month` (as the exact length
+  > of a month depends on the current month). `add/3` always considers
+  > the unit to be computed according to the `Calendar.ISO`.
+
   Accepts an `amount_to_add` in any `unit`. `unit` can be `:day`,
   `:hour`, `:minute`, `:second` or any subsecond precision from
   `t:System.time_unit/0`. It defaults to `:second`. Negative values
   will move backwards in time.
 
-  This function always considers the unit to be computed according
-  to the `Calendar.ISO`.
-
   This function relies on a contiguous representation of time,
-  ignoring the wall time and timezone changes. For example, if you add
-  one day when there are summer time/daylight saving time changes,
-  it will also change the time forward or backward by one hour,
-  so the elapsed time is precisely 24 hours. Similarly, adding just
-  a few seconds to a datetime just before "spring forward" can cause
-  wall time to increase by more than an hour.
+  ignoring timezone changes. For example, if you add one day when there
+  are summer time/daylight saving time changes, it will also change the
+  time forward or backward by one hour, so the elapsed time is precisely
+  24 hours. Similarly, adding just a few seconds to a datetime just before
+  "spring forward" can cause wall time to increase by more than an hour.
 
   While this means this function is precise in terms of elapsed time,
-  its result may be misleading in certain use cases. For example, if a
+  its result may be confusing in certain use cases. For example, if a
   user requests a meeting to happen every day at 15:00 and you use this
   function to compute all future meetings by adding day after day, this
   function may change the meeting time to 14:00 or 16:00 if there are
-  changes to the current timezone. Computing of recurring datetimes is
-  not currently supported in Elixir's standard library but it is available
-  by third-party libraries.
+  changes to the current timezone.
 
-  ### Examples
+  In case you don't want these changes to happen automatically or you
+  want to surface time zone conflicts to the user, you can add to
+  the datetime as a naive datetime and then use `from_naive/2`:
+
+      dt |> NaiveDateTime.add(1, :day) |> DateTime.from_naive(dt.time_zone)
+
+  The above will surface time jumps and ambiguous datetimes, allowing you
+  to deal with them accordingly.
+
+  ## Examples
 
       iex> dt = DateTime.from_naive!(~N[2018-11-15 10:00:00], "Europe/Copenhagen", FakeTimeZoneDatabase)
       iex> dt |> DateTime.add(3600, :second, FakeTimeZoneDatabase)
@@ -1626,8 +1676,6 @@ defmodule DateTime do
       iex> result.microsecond
       {21000, 3}
 
-  To shift a datetime by a `Duration` and according to its underlying calendar, use `DateTime.shift/3`.
-
   """
   @doc since: "1.8.0"
   @spec add(
@@ -1701,7 +1749,7 @@ defmodule DateTime do
   to UTC, and finally computing the new timezone in case of shifts.
   This ensures `shift/3` always returns a valid datetime.
 
-  On the other hand, time zones that observe "Daylight Saving Time"
+  Consequently, time zones that observe "Daylight Saving Time"
   or other changes, across summer/winter time will add/remove hours
   from the resulting datetime:
 
@@ -1713,12 +1761,22 @@ defmodule DateTime do
       DateTime.shift(dt, hour: 2)
       #=> #DateTime<2018-11-04 01:00:00-08:00 PST America/Los_Angeles>
 
+  Although the first example shows a difference of 2 hours when
+  comparing the wall clocks of the given datetime with the returned one,
+  due to the "spring forward" time jump, the actual elapsed time is
+  still exactly of 1 hour.
+
   In case you don't want these changes to happen automatically or you
   want to surface time zone conflicts to the user, you can shift
   the datetime as a naive datetime and then use `from_naive/2`:
 
       dt |> NaiveDateTime.shift(duration) |> DateTime.from_naive(dt.time_zone)
 
+  The above will surface time jumps and ambiguous datetimes, allowing you
+  to deal with them accordingly.
+
+  ## ISO calendar considerations
+
   When using the default ISO calendar, durations are collapsed and
   applied in the order of months, then seconds and microseconds:
 
@@ -1884,7 +1942,7 @@ defmodule DateTime do
   ## Examples
 
   Imagine someone implements `Calendar.Holocene`, a calendar based on the
-  Gregorian calendar that adds exactly 10,000 years to the current Gregorian
+  Gregorian calendar that adds exactly 10 000 years to the current Gregorian
   year:
 
       iex> dt1 = %DateTime{year: 2000, month: 2, day: 29, zone_abbr: "AMT",
@@ -1913,7 +1971,7 @@ defmodule DateTime do
     if Calendar.compatible_calendars?(dt_calendar, calendar) do
       result_datetime =
         datetime
-        |> to_iso_days
+        |> to_iso_days()
         |> from_iso_days(datetime, calendar, precision)
 
       {:ok, result_datetime}
@@ -1931,7 +1989,7 @@ defmodule DateTime do
   ## Examples
 
   Imagine someone implements `Calendar.Holocene`, a calendar based on the
-  Gregorian calendar that adds exactly 10,000 years to the current Gregorian
+  Gregorian calendar that adds exactly 10 000 years to the current Gregorian
   year:
 
       iex> dt1 = %DateTime{year: 2000, month: 2, day: 29, zone_abbr: "AMT",

lib/elixir/lib/calendar/duration.ex

@@ -1,3 +1,6 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
 defmodule Duration do
   @moduledoc """
   Struct and functions for handling durations.
@@ -88,6 +91,30 @@ defmodule Duration do
   The second example consistently points to the last day of the month,
   as it performs operations on the duration, rather than shifting date
   after date.
+
+  ## Comparing durations
+
+  In order to accurately compare durations, you need to either compare
+  only certain fields or use a reference time instant. This is because
+  some fields are relative to others. For example, you may say that
+  1 month is the same as 30 days, but if you add both of these durations
+  to `~D[2015-02-01]`, you would get different results, as that month
+  has only 28 days.
+
+  Therefore, if you wish to compare durations, one option is to use
+  `Date.shift/2` (or `DateTime.shift/2` or similar), and then compare
+  the dates:
+
+      iex> date = ~D[2015-02-01]
+      iex> Date.compare(Date.shift(date, month: 1), Date.shift(date, day: 30))
+      :lt
+
+  Or alternatively convert the durations to a fixed unit by using `to_timeout/1`,
+  which supports durations only up to weeks, raising if it has the month or year
+  fields set.
+
+      iex> to_timeout(hour: 24) == to_timeout(day: 1)
+      true
   """
 
   @moduledoc since: "1.17.0"
@@ -113,7 +140,7 @@ defmodule Duration do
           hour: integer,
           minute: integer,
           second: integer,
-          microsecond: {integer, 0..6}
+          microsecond: Calendar.microsecond()
         }
 
   @typedoc """
@@ -127,13 +154,29 @@ defmodule Duration do
           | {:hour, integer}
           | {:minute, integer}
           | {:second, integer}
-          | {:microsecond, {integer, 0..6}}
+          | {:microsecond, Calendar.microsecond()}
 
   @typedoc """
   The duration type specifies a `%Duration{}` struct or a keyword list of valid duration unit pairs.
   """
   @type duration :: t | [unit_pair]
 
+  @typedoc """
+  Options for `Duration.to_string/2`.
+  """
+  @type to_string_opts :: [
+          units: [
+            year: String.t(),
+            month: String.t(),
+            week: String.t(),
+            day: String.t(),
+            hour: String.t(),
+            minute: String.t(),
+            second: String.t()
+          ],
+          separator: String.t()
+        ]
+
   @microseconds_per_second 1_000_000
 
   @doc """
@@ -409,6 +452,7 @@ defmodule Duration do
 
   """
   @doc since: "1.18.0"
+  @spec to_string(t, to_string_opts) :: String.t()
   def to_string(%Duration{} = duration, opts \\ []) do
     units = Keyword.get(opts, :units, [])
     separator = Keyword.get(opts, :separator, " ")
@@ -532,7 +576,7 @@ defmodule Duration do
       sign,
       Integer.to_string(second),
       ?.,
-      ms |> Integer.to_string() |> String.pad_leading(6, "0") |> binary_part(0, p)
+      Calendar.ISO.microseconds_to_iodata(ms, p)
     ]
   end
 

lib/elixir/lib/calendar/iso.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Calendar.ISO do
   @moduledoc """
   The default calendar implementation, a Gregorian calendar following ISO 8601.
@@ -1220,6 +1224,37 @@ defmodule Calendar.ISO do
           :basic | :extended
         ) :: String.t()
   def time_to_string(
+        hour,
+        minute,
+        second,
+        microsecond,
+        format \\ :extended
+      ) do
+    time_to_iodata(hour, minute, second, microsecond, format)
+    |> IO.iodata_to_binary()
+  end
+
+  @doc """
+  Converts the given time into a iodata.
+
+  See `time_to_string/5` for more information.
+
+  ## Examples
+
+      iex> data = Calendar.ISO.time_to_iodata(2, 2, 2, {2, 6})
+      iex> IO.iodata_to_binary(data)
+      "02:02:02.000002"
+
+  """
+  @doc since: "1.19.0"
+  @spec time_to_iodata(
+          Calendar.hour(),
+          Calendar.minute(),
+          Calendar.second(),
+          Calendar.microsecond(),
+          :basic | :extended
+        ) :: iodata
+  def time_to_iodata(
         hour,
         minute,
         second,
@@ -1228,24 +1263,43 @@ defmodule Calendar.ISO do
       )
       when is_hour(hour) and is_minute(minute) and is_second(second) and
              is_microsecond(ms_value, ms_precision) and format in [:basic, :extended] do
-    time_to_string_guarded(hour, minute, second, microsecond, format)
+    time_to_iodata_guarded(hour, minute, second, microsecond, format)
   end
 
-  defp time_to_string_guarded(hour, minute, second, {_, 0}, format) do
-    time_to_string_format(hour, minute, second, format)
+  defp time_to_iodata_guarded(hour, minute, second, {_, 0}, format) do
+    time_to_iodata_format(hour, minute, second, format)
   end
 
-  defp time_to_string_guarded(hour, minute, second, {microsecond, precision}, format) do
-    time_to_string_format(hour, minute, second, format) <>
-      "." <> (microsecond |> zero_pad(6) |> binary_part(0, precision))
+  defp time_to_iodata_guarded(hour, minute, second, {microsecond, precision}, format) do
+    [
+      time_to_iodata_format(hour, minute, second, format),
+      ?.
+      | microseconds_to_iodata(microsecond, precision)
+    ]
   end
 
-  defp time_to_string_format(hour, minute, second, :extended) do
-    zero_pad(hour, 2) <> ":" <> zero_pad(minute, 2) <> ":" <> zero_pad(second, 2)
+  @doc false
+  def microseconds_to_iodata(_microsecond, 0), do: []
+  def microseconds_to_iodata(microsecond, 6), do: zero_pad(microsecond, 6)
+
+  def microseconds_to_iodata(microsecond, precision) do
+    num = div(microsecond, scale_factor(precision))
+    zero_pad(num, precision)
   end
 
-  defp time_to_string_format(hour, minute, second, :basic) do
-    zero_pad(hour, 2) <> zero_pad(minute, 2) <> zero_pad(second, 2)
+  defp scale_factor(1), do: 100_000
+  defp scale_factor(2), do: 10_000
+  defp scale_factor(3), do: 1_000
+  defp scale_factor(4), do: 100
+  defp scale_factor(5), do: 10
+  defp scale_factor(6), do: 1
+
+  defp time_to_iodata_format(hour, minute, second, :extended) do
+    [zero_pad(hour, 2), ?:, zero_pad(minute, 2), ?: | zero_pad(second, 2)]
+  end
+
+  defp time_to_iodata_format(hour, minute, second, :basic) do
+    [zero_pad(hour, 2), zero_pad(minute, 2) | zero_pad(second, 2)]
   end
 
   @doc """
@@ -1273,18 +1327,36 @@ defmodule Calendar.ISO do
   @doc since: "1.4.0"
   @spec date_to_string(year, month, day, :basic | :extended) :: String.t()
   @impl true
-  def date_to_string(year, month, day, format \\ :extended)
+  def date_to_string(year, month, day, format \\ :extended) do
+    date_to_iodata(year, month, day, format)
+    |> IO.iodata_to_binary()
+  end
+
+  @doc """
+  Converts the given date into a iodata.
+
+  See `date_to_string/4` for more information.
+
+  ## Examples
+
+      iex> data = Calendar.ISO.date_to_iodata(2015, 2, 28)
+      iex> IO.iodata_to_binary(data)
+      "2015-02-28"
+  """
+  @doc since: "1.19.0"
+  @spec date_to_iodata(year, month, day, :basic | :extended) :: iodata
+  def date_to_iodata(year, month, day, format \\ :extended)
       when is_integer(year) and is_integer(month) and is_integer(day) and
              format in [:basic, :extended] do
-    date_to_string_guarded(year, month, day, format)
+    date_to_iodata_guarded(year, month, day, format)
   end
 
-  defp date_to_string_guarded(year, month, day, :extended) do
-    zero_pad(year, 4) <> "-" <> zero_pad(month, 2) <> "-" <> zero_pad(day, 2)
+  defp date_to_iodata_guarded(year, month, day, :extended) do
+    [zero_pad(year, 4), ?-, zero_pad(month, 2), ?- | zero_pad(day, 2)]
   end
 
-  defp date_to_string_guarded(year, month, day, :basic) do
-    zero_pad(year, 4) <> zero_pad(month, 2) <> zero_pad(day, 2)
+  defp date_to_iodata_guarded(year, month, day, :basic) do
+    [zero_pad(year, 4), zero_pad(month, 2) | zero_pad(day, 2)]
   end
 
   @doc """
@@ -1327,8 +1399,61 @@ defmodule Calendar.ISO do
         microsecond,
         format \\ :extended
       ) do
-    date_to_string(year, month, day, format) <>
-      " " <> time_to_string(hour, minute, second, microsecond, format)
+    naive_datetime_to_iodata(
+      year,
+      month,
+      day,
+      hour,
+      minute,
+      second,
+      microsecond,
+      format
+    )
+    |> IO.iodata_to_binary()
+  end
+
+  @doc """
+  Converts the given naive_datetime into a iodata.
+
+  See `naive_datetime_to_iodata/8` for more information.
+
+  ## Examples
+
+      iex> data = Calendar.ISO.naive_datetime_to_iodata(2015, 2, 28, 1, 2, 3, {4, 6}, :basic)
+      iex> IO.iodata_to_binary(data)
+      "20150228 010203.000004"
+
+      iex> data = Calendar.ISO.naive_datetime_to_iodata(2015, 2, 28, 1, 2, 3, {4, 6}, :extended)
+      iex> IO.iodata_to_binary(data)
+      "2015-02-28 01:02:03.000004"
+
+  """
+  @doc since: "1.19.0"
+  @spec naive_datetime_to_iodata(
+          year,
+          month,
+          day,
+          Calendar.hour(),
+          Calendar.minute(),
+          Calendar.second(),
+          Calendar.microsecond(),
+          :basic | :extended
+        ) :: iodata
+  def naive_datetime_to_iodata(
+        year,
+        month,
+        day,
+        hour,
+        minute,
+        second,
+        microsecond,
+        format \\ :extended
+      ) do
+    [
+      date_to_iodata(year, month, day, format),
+      ?\s
+      | time_to_iodata(hour, minute, second, microsecond, format)
+    ]
   end
 
   @doc """
@@ -1394,20 +1519,89 @@ defmodule Calendar.ISO do
         utc_offset,
         std_offset,
         format \\ :extended
+      ) do
+    datetime_to_iodata(
+      year,
+      month,
+      day,
+      hour,
+      minute,
+      second,
+      microsecond,
+      time_zone,
+      zone_abbr,
+      utc_offset,
+      std_offset,
+      format
+    )
+    |> IO.iodata_to_binary()
+  end
+
+  @doc """
+  Converts the given datetime into a iodata.
+
+  See `datetime_to_iodata/12` for more information.
+
+  ## Examples
+
+      iex> time_zone = "Etc/UTC"
+      iex> data = Calendar.ISO.datetime_to_iodata(2017, 8, 1, 1, 2, 3, {4, 5}, time_zone, "UTC", 0, 0)
+      iex> IO.iodata_to_binary(data)
+      "2017-08-01 01:02:03.00000Z"
+
+  """
+  @doc since: "1.19.0"
+  @spec datetime_to_iodata(
+          year,
+          month,
+          day,
+          Calendar.hour(),
+          Calendar.minute(),
+          Calendar.second(),
+          Calendar.microsecond(),
+          Calendar.time_zone(),
+          Calendar.zone_abbr(),
+          Calendar.utc_offset(),
+          Calendar.std_offset(),
+          :basic | :extended
+        ) :: iodata
+  def datetime_to_iodata(
+        year,
+        month,
+        day,
+        hour,
+        minute,
+        second,
+        microsecond,
+        time_zone,
+        zone_abbr,
+        utc_offset,
+        std_offset,
+        format \\ :extended
       )
       when is_time_zone(time_zone) and is_zone_abbr(zone_abbr) and is_utc_offset(utc_offset) and
              is_std_offset(std_offset) do
-    date_to_string(year, month, day, format) <>
-      " " <>
-      time_to_string(hour, minute, second, microsecond, format) <>
-      offset_to_string(utc_offset, std_offset, time_zone, format) <>
-      zone_to_string(utc_offset, std_offset, zone_abbr, time_zone)
+    [
+      date_to_iodata(year, month, day, format),
+      ?\s,
+      time_to_iodata(hour, minute, second, microsecond, format),
+      offset_to_iodata(utc_offset, std_offset, time_zone, format),
+      zone_to_iodata(utc_offset, std_offset, zone_abbr, time_zone)
+    ]
   end
 
   @doc false
   def offset_to_string(0, 0, "Etc/UTC", _format), do: "Z"
 
-  def offset_to_string(utc, std, _zone, format) do
+  def offset_to_string(utc, std, zone, format) do
+    offset_to_iodata(utc, std, zone, format)
+    |> IO.iodata_to_binary()
+  end
+
+  @doc false
+  def offset_to_iodata(0, 0, "Etc/UTC", _format), do: ?Z
+
+  def offset_to_iodata(utc, std, _zone, format) do
     total = utc + std
     second = abs(total)
     minute = second |> rem(3600) |> div(60)
@@ -1416,15 +1610,15 @@ defmodule Calendar.ISO do
   end
 
   defp format_offset(total, hour, minute, :extended) do
-    sign(total) <> zero_pad(hour, 2) <> ":" <> zero_pad(minute, 2)
+    [sign(total), zero_pad(hour, 2), ?: | zero_pad(minute, 2)]
   end
 
   defp format_offset(total, hour, minute, :basic) do
-    sign(total) <> zero_pad(hour, 2) <> zero_pad(minute, 2)
+    [sign(total), zero_pad(hour, 2) | zero_pad(minute, 2)]
   end
 
-  defp zone_to_string(_, _, _, "Etc/UTC"), do: ""
-  defp zone_to_string(_, _, abbr, zone), do: " " <> abbr <> " " <> zone
+  defp zone_to_iodata(_, _, _, "Etc/UTC"), do: []
+  defp zone_to_iodata(_, _, abbr, zone), do: [?\s, abbr, ?\s | zone]
 
   @doc """
   Determines if the date given is valid according to the proleptic Gregorian calendar.
@@ -1485,16 +1679,24 @@ defmodule Calendar.ISO do
     {0, 1}
   end
 
-  defp sign(total) when total < 0, do: "-"
-  defp sign(_), do: "+"
+  defp sign(total) when total < 0, do: ?-
+  defp sign(_), do: ?+
 
-  defp zero_pad(val, count) when val >= 0 do
+  defp zero_pad(val, count) when val >= 0 and count <= 6 do
     num = Integer.to_string(val)
-    :binary.copy("0", max(count - byte_size(num), 0)) <> num
+
+    case max(count - byte_size(num), 0) do
+      0 -> num
+      1 -> ["0" | num]
+      2 -> ["00" | num]
+      3 -> ["000" | num]
+      4 -> ["0000" | num]
+      5 -> ["00000" | num]
+    end
   end
 
   defp zero_pad(val, count) do
-    "-" <> zero_pad(-val, count)
+    [?- | zero_pad(-val, count)]
   end
 
   @doc """
@@ -1791,16 +1993,13 @@ defmodule Calendar.ISO do
   end
 
   defp parse_microsecond("." <> rest) do
-    case parse_microsecond(rest, 0, "") do
-      {"", 0, _} ->
+    case parse_microsecond(rest, 0, []) do
+      {[], 0, _} ->
         :error
 
-      {microsecond, precision, rest} when precision in 1..6 ->
-        pad = String.duplicate("0", 6 - byte_size(microsecond))
-        {{String.to_integer(microsecond <> pad), precision}, rest}
-
-      {microsecond, _precision, rest} ->
-        {{String.to_integer(binary_part(microsecond, 0, 6)), 6}, rest}
+      {microsecond, precision, rest} ->
+        scale = scale_factor(precision)
+        {{:erlang.list_to_integer(microsecond) * scale, precision}, rest}
     end
   end
 
@@ -1812,34 +2011,42 @@ defmodule Calendar.ISO do
     {{0, 0}, rest}
   end
 
-  defp parse_microsecond(<<head, tail::binary>>, precision, acc) when head in ?0..?9,
-    do: parse_microsecond(tail, precision + 1, <<acc::binary, head>>)
+  defp parse_microsecond(<<head, tail::binary>>, 6, acc) when head in ?0..?9,
+    do: parse_microsecond(tail, 6, acc)
 
-  defp parse_microsecond(rest, precision, acc), do: {acc, precision, rest}
+  defp parse_microsecond(<<head, tail::binary>>, precision, acc) when head in ?0..?9,
+    do: parse_microsecond(tail, precision + 1, [head | acc])
+
+  defp parse_microsecond(rest, precision, acc) do
+    {:lists.reverse(acc), precision, rest}
+  end
 
   defp parse_offset(""), do: {nil, ""}
   defp parse_offset("Z"), do: {0, ""}
   defp parse_offset("-00:00"), do: :error
 
-  defp parse_offset(<<?+, hour::2-bytes, ?:, min::2-bytes, rest::binary>>),
-    do: parse_offset(1, hour, min, rest)
+  defp parse_offset(<<?+, h1, h2, ?:, m1, m2, rest::binary>>),
+    do: parse_offset(1, h1, h2, m1, m2, rest)
 
-  defp parse_offset(<<?-, hour::2-bytes, ?:, min::2-bytes, rest::binary>>),
-    do: parse_offset(-1, hour, min, rest)
+  defp parse_offset(<<?-, h1, h2, ?:, m1, m2, rest::binary>>),
+    do: parse_offset(-1, h1, h2, m1, m2, rest)
 
-  defp parse_offset(<<?+, hour::2-bytes, min::2-bytes, rest::binary>>),
-    do: parse_offset(1, hour, min, rest)
+  defp parse_offset(<<?+, h1, h2, m1, m2, rest::binary>>),
+    do: parse_offset(1, h1, h2, m1, m2, rest)
 
-  defp parse_offset(<<?-, hour::2-bytes, min::2-bytes, rest::binary>>),
-    do: parse_offset(-1, hour, min, rest)
+  defp parse_offset(<<?-, h1, h2, m1, m2, rest::binary>>),
+    do: parse_offset(-1, h1, h2, m1, m2, rest)
 
-  defp parse_offset(<<?+, hour::2-bytes, rest::binary>>), do: parse_offset(1, hour, "00", rest)
-  defp parse_offset(<<?-, hour::2-bytes, rest::binary>>), do: parse_offset(-1, hour, "00", rest)
+  defp parse_offset(<<?+, h1, h2, rest::binary>>), do: parse_offset(1, h1, h2, ?0, ?0, rest)
+  defp parse_offset(<<?-, h1, h2, rest::binary>>), do: parse_offset(-1, h1, h2, ?0, ?0, rest)
   defp parse_offset(_), do: :error
 
-  defp parse_offset(sign, hour, min, rest) do
-    with {hour, ""} when hour < 24 <- Integer.parse(hour),
-         {min, ""} when min < 60 <- Integer.parse(min) do
+  defp parse_offset(sign, h1, h2, m1, m2, rest) do
+    with true <- h1 in ?0..?2 and h2 in ?0..?9,
+         true <- m1 in ?0..?5 and m2 in ?0..?9,
+         hour = (h1 - ?0) * 10 + h2 - ?0,
+         min = (m1 - ?0) * 10 + m2 - ?0,
+         true <- hour < 24 do
       {(hour * 60 + min) * 60 * sign, rest}
     else
       _ -> :error

lib/elixir/lib/calendar/naive_datetime.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule NaiveDateTime do
   @moduledoc """
   A NaiveDateTime struct (without a time zone) and functions.
@@ -36,10 +40,10 @@ defmodule NaiveDateTime do
 
   Comparisons in Elixir using `==/2`, `>/2`, `</2` and similar are structural
   and based on the `NaiveDateTime` struct fields. For proper comparison
-  between naive datetimes, use the `compare/2` function. The existence of the
-  `compare/2` function in this module also allows using `Enum.min/2` and
-  `Enum.max/2` functions to get the minimum and maximum naive datetime of an
-  `Enum`. For example:
+  between naive datetimes, use the `compare/2`, `after?/2` and `before?/2` functions.
+  The existence of the `compare/2` function in this module also allows
+  using `Enum.min/2` and `Enum.max/2` functions to get the minimum and
+  maximum naive datetime of an `Enum`. For example:
 
       iex> Enum.min([~N[2020-01-01 23:00:07], ~N[2000-01-01 23:00:07]], NaiveDateTime)
       ~N[2000-01-01 23:00:07]
@@ -387,14 +391,20 @@ defmodule NaiveDateTime do
   @doc """
   Adds a specified amount of time to a `NaiveDateTime`.
 
+  > #### Prefer `shift/2` {: .info}
+  >
+  > Prefer `shift/2` over `add/3`, as it offers a more ergonomic API.
+  >
+  > `add/3` provides a lower-level API which only supports fixed units
+  > such as `:hour` and `:second`, but not `:month` (as the exact length
+  > of a month depends on the current month). `add/3` always considers
+  > the unit to be computed according to the `Calendar.ISO`.
+
   Accepts an `amount_to_add` in any `unit`. `unit` can be `:day`,
   `:hour`, `:minute`, `:second` or any subsecond precision from
   `t:System.time_unit/0`. It defaults to `:second`. Negative values
   will move backwards in time.
 
-  This function always consider the unit to be computed according
-  to the `Calendar.ISO`.
-
   ## Examples
 
   It uses seconds by default:
@@ -443,8 +453,6 @@ defmodule NaiveDateTime do
       iex> NaiveDateTime.add(dt, 21, :second)
       ~N[2000-02-29 23:00:28]
 
-  To shift a naive datetime by a `Duration` and according to its underlying calendar, use `NaiveDateTime.shift/2`.
-
   """
   @doc since: "1.4.0"
   @spec add(Calendar.naive_datetime(), integer, :day | :hour | :minute | System.time_unit()) :: t
@@ -754,10 +762,10 @@ defmodule NaiveDateTime do
   @doc """
   Converts the given naive datetime to a string according to its calendar.
 
-  For redability, this function follows the RFC3339 suggestion of removing
+  For readability, this function follows the RFC3339 suggestion of removing
   the "T" separator between the date and time components.
 
-  ### Examples
+  ## Examples
 
       iex> NaiveDateTime.to_string(~N[2000-02-28 23:00:13])
       "2000-02-28 23:00:13"
@@ -904,7 +912,7 @@ defmodule NaiveDateTime do
   Only supports converting naive datetimes which are in the ISO calendar,
   attempting to convert naive datetimes from other calendars will raise.
 
-  ### Examples
+  ## Examples
 
       iex> NaiveDateTime.to_iso8601(~N[2000-02-28 23:00:13])
       "2000-02-28T23:00:13"
@@ -930,6 +938,19 @@ defmodule NaiveDateTime do
 
   def to_iso8601(%{calendar: Calendar.ISO} = naive_datetime, format)
       when format in [:basic, :extended] do
+    naive_datetime
+    |> to_iso8601_iodata(format)
+    |> IO.iodata_to_binary()
+  end
+
+  def to_iso8601(%{calendar: _} = naive_datetime, format)
+      when format in [:basic, :extended] do
+    naive_datetime
+    |> convert!(Calendar.ISO)
+    |> to_iso8601(format)
+  end
+
+  defp to_iso8601_iodata(naive_datetime, format) do
     %{
       year: year,
       month: month,
@@ -940,14 +961,11 @@ defmodule NaiveDateTime do
       microsecond: microsecond
     } = naive_datetime
 
-    Calendar.ISO.date_to_string(year, month, day, format) <>
-      "T" <> Calendar.ISO.time_to_string(hour, minute, second, microsecond, format)
-  end
-
-  def to_iso8601(%{calendar: _} = naive_datetime, format) when format in [:basic, :extended] do
-    naive_datetime
-    |> convert!(Calendar.ISO)
-    |> to_iso8601(format)
+    [
+      Calendar.ISO.date_to_iodata(year, month, day, format),
+      ?T,
+      Calendar.ISO.time_to_iodata(hour, minute, second, microsecond, format)
+    ]
   end
 
   @doc """
@@ -1247,7 +1265,7 @@ defmodule NaiveDateTime do
   ## Examples
 
   Imagine someone implements `Calendar.Holocene`, a calendar based on the
-  Gregorian calendar that adds exactly 10,000 years to the current Gregorian
+  Gregorian calendar that adds exactly 10 000 years to the current Gregorian
   year:
 
       iex> NaiveDateTime.convert(~N[2000-01-01 13:30:15], Calendar.Holocene)
@@ -1295,7 +1313,7 @@ defmodule NaiveDateTime do
     if Calendar.compatible_calendars?(ndt_calendar, calendar) do
       result_naive_datetime =
         naive_datetime
-        |> to_iso_days
+        |> to_iso_days()
         |> from_iso_days(calendar, precision)
 
       {:ok, result_naive_datetime}
@@ -1313,7 +1331,7 @@ defmodule NaiveDateTime do
   ## Examples
 
   Imagine someone implements `Calendar.Holocene`, a calendar based on the
-  Gregorian calendar that adds exactly 10,000 years to the current Gregorian
+  Gregorian calendar that adds exactly 10 000 years to the current Gregorian
   year:
 
       iex> NaiveDateTime.convert!(~N[2000-01-01 13:30:15], Calendar.Holocene)

lib/elixir/lib/calendar/time.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Time do
   @moduledoc """
   A Time struct and functions.
@@ -31,9 +35,10 @@ defmodule Time do
 
   Comparisons in Elixir using `==/2`, `>/2`, `</2` and similar are structural
   and based on the `Time` struct fields. For proper comparison between
-  times, use the `compare/2` function. The existence of the `compare/2`
-  function in this module also allows using `Enum.min/2` and `Enum.max/2`
-  functions to get the minimum and maximum time of an `Enum`. For example:
+  times, use the `compare/2`, `after?/2` and `before?/2` functions.
+  The existence of the `compare/2` function in this module also allows
+  using `Enum.min/2` and `Enum.max/2` functions to get the minimum and
+  maximum time of an `Enum`. For example:
 
       iex> Enum.min([~T[23:00:07.001], ~T[10:00:07.001]], Time)
       ~T[10:00:07.001]
@@ -55,17 +60,52 @@ defmodule Time do
   @doc """
   Returns the current time in UTC.
 
+  You can pass a time unit to automatically truncate the resulting time.
+
+  The default unit if none gets passed is `:native` which results on a default resolution of microseconds.
+
   ## Examples
 
       iex> time = Time.utc_now()
       iex> time.hour >= 0
       true
 
+      iex> time = Time.utc_now(:second)
+      iex> time.microsecond
+      {0, 0}
+
   """
   @doc since: "1.4.0"
-  @spec utc_now(Calendar.calendar()) :: t
-  def utc_now(calendar \\ Calendar.ISO) do
-    {:ok, _, time, microsecond} = Calendar.ISO.from_unix(:os.system_time(), :native)
+  @spec utc_now(Calendar.calendar() | :native | :microsecond | :millisecond | :second) :: t
+  def utc_now(calendar_or_time_unit \\ Calendar.ISO) do
+    case calendar_or_time_unit do
+      unit when unit in [:native, :microsecond, :millisecond, :second] ->
+        utc_now(unit, Calendar.ISO)
+
+      calendar ->
+        utc_now(:native, calendar)
+    end
+  end
+
+  @doc """
+  Returns the current time in UTC, supporting a precision and a specific calendar.
+
+  ## Examples
+
+      iex> time = Time.utc_now(:microsecond, Calendar.ISO)
+      iex> time.hour >= 0
+      true
+
+      iex> time = Time.utc_now(:second, Calendar.ISO)
+      iex> time.microsecond
+      {0, 0}
+
+  """
+  @doc since: "1.19.0"
+  @spec utc_now(:native | :microsecond | :millisecond | :second, Calendar.calendar()) :: t
+  def utc_now(time_unit, calendar)
+      when time_unit in [:native, :microsecond, :millisecond, :second] do
+    {:ok, _, time, microsecond} = Calendar.ISO.from_unix(System.os_time(time_unit), time_unit)
     {hour, minute, second} = time
 
     iso_time = %Time{
@@ -185,7 +225,7 @@ defmodule Time do
   @doc """
   Converts the given `time` to a string.
 
-  ### Examples
+  ## Examples
 
       iex> Time.to_string(~T[23:00:00])
       "23:00:00"
@@ -294,7 +334,7 @@ defmodule Time do
   format, for human readability. It also supports the "basic" format through
   passing the `:basic` option.
 
-  ### Examples
+  ## Examples
 
       iex> Time.to_iso8601(~T[23:00:13])
       "23:00:13"
@@ -465,14 +505,18 @@ defmodule Time do
   @doc """
   Adds the `amount_to_add` of `unit`s to the given `time`.
 
+  > #### Prefer `shift/2` {: .info}
+  >
+  > Prefer `shift/2` over `add/3`, as it offers a more ergonomic API.
+  >
+  > `add/3` always considers the unit to be computed according to
+  > the `Calendar.ISO`.
+
   Accepts an `amount_to_add` in any `unit`. `unit` can be
   `:hour`, `:minute`, `:second` or any subsecond precision from
   `t:System.time_unit/0`. It defaults to `:second`. Negative values
   will move backwards in time.
 
-  This function always consider the unit to be computed according
-  to the `Calendar.ISO`.
-
   Note the result value represents the time of day, meaning that it is cyclic,
   for instance, it will never go over 24 hours for the ISO calendar.
 
@@ -509,8 +553,6 @@ defmodule Time do
       iex> result.microsecond
       {21000, 3}
 
-  To shift a time by a `Duration` and according to its underlying calendar, use `Time.shift/2`.
-
   """
   @doc since: "1.6.0"
   @spec add(Calendar.time(), integer, :hour | :minute | System.time_unit()) :: t
@@ -741,7 +783,7 @@ defmodule Time do
   ## Examples
 
   Imagine someone implements `Calendar.Holocene`, a calendar based on the
-  Gregorian calendar that adds exactly 10,000 years to the current Gregorian
+  Gregorian calendar that adds exactly 10 000 years to the current Gregorian
   year:
 
       iex> Time.convert(~T[13:30:15], Calendar.Holocene)
@@ -797,7 +839,7 @@ defmodule Time do
   ## Examples
 
   Imagine someone implements `Calendar.Holocene`, a calendar based on the
-  Gregorian calendar that adds exactly 10,000 years to the current Gregorian
+  Gregorian calendar that adds exactly 10 000 years to the current Gregorian
   year:
 
       iex> Time.convert!(~T[13:30:15], Calendar.Holocene)

lib/elixir/lib/calendar/time_zone_database.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Calendar.TimeZoneDatabase do
   @moduledoc """
   This module defines a behaviour for providing time zone data.

lib/elixir/lib/code.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Code do
   @moduledoc ~S"""
   Utilities for managing code compilation, code evaluation, and code loading.
@@ -244,19 +248,71 @@ defmodule Code do
   """
   @type position() :: line() | {line :: pos_integer(), column :: pos_integer()}
 
+  @typedoc """
+  Options for code formatting functions.
+  """
+  @type format_opt ::
+          {:file, binary()}
+          | {:line, pos_integer()}
+          | {:line_length, pos_integer()}
+          | {:locals_without_parens, keyword()}
+          | {:force_do_end_blocks, boolean()}
+          | {:migrate, boolean()}
+          | {:migrate_bitstring_modifiers, boolean()}
+          | {:migrate_call_parens_on_pipe, boolean()}
+          | {:migrate_charlists_as_sigils, boolean()}
+          | {:migrate_unless, boolean()}
+          | {atom(), term()}
+
+  @typedoc """
+  Options for `quoted_to_algebra/2`.
+  """
+  @type quoted_to_algebra_opt ::
+          {:line, pos_integer() | nil}
+          | {:escape, boolean()}
+          | {:locals_without_parens, keyword()}
+          | {:comments, [term()]}
+
+  @typedoc """
+  Options for parsing functions that convert strings to quoted expressions.
+  """
+  @type parser_opts :: [
+          file: binary(),
+          line: pos_integer(),
+          column: pos_integer(),
+          indentation: non_neg_integer(),
+          columns: boolean(),
+          unescape: boolean(),
+          existing_atoms_only: boolean(),
+          token_metadata: boolean(),
+          literal_encoder: (term(), Macro.metadata() -> term()),
+          static_atoms_encoder: (atom() -> term()),
+          emit_warnings: boolean()
+        ]
+
+  @typedoc """
+  Options for environment evaluation functions like eval_string/3 and eval_quoted/3.
+  """
+  @type env_eval_opts :: [
+          file: binary(),
+          line: pos_integer(),
+          module: module(),
+          prune_binding: boolean()
+        ]
+
   @boolean_compiler_options [
     :docs,
     :debug_info,
     :ignore_already_consolidated,
     :ignore_module_conflict,
-    :infer_signatures,
     :relative_paths
   ]
 
-  @list_compiler_options [:no_warn_undefined, :tracers, :parser_options]
+  @list_compiler_options [:tracers, :parser_options]
 
   @available_compiler_options @boolean_compiler_options ++
-                                @list_compiler_options ++ [:on_undefined_variable]
+                                @list_compiler_options ++
+                                [:on_undefined_variable, :infer_signatures, :no_warn_undefined]
 
   @doc """
   Lists all required files.
@@ -343,7 +399,7 @@ defmodule Code do
 
     * `:cache` - (since v1.15.0) when true, the code path is cached
       the first time it is traversed in order to reduce file system
-      operations. It requires Erlang/OTP 26, otherwise it is a no-op.
+      operations.
 
   """
   @spec append_path(Path.t(), cache: boolean()) :: true | false
@@ -374,7 +430,7 @@ defmodule Code do
 
     * `:cache` - (since v1.15.0) when true, the code path is cached
       the first time it is traversed in order to reduce file system
-      operations. It requires Erlang/OTP 26, otherwise it is a no-op.
+      operations.
 
   """
   @spec prepend_path(Path.t(), cache: boolean()) :: boolean()
@@ -403,7 +459,7 @@ defmodule Code do
 
     * `:cache` - when true, the code path is cached the first time
       it is traversed in order to reduce file system operations.
-      It requires Erlang/OTP 26, otherwise it is a no-op.
+
   """
   @doc since: "1.15.0"
   @spec prepend_paths([Path.t()], cache: boolean()) :: :ok
@@ -432,7 +488,7 @@ defmodule Code do
 
     * `:cache` - when true, the code path is cached the first time
       it is traversed in order to reduce file system operations.
-      It requires Erlang/OTP 26, otherwise it is a no-op.
+
   """
   @doc since: "1.15.0"
   @spec append_paths([Path.t()], cache: boolean()) :: :ok
@@ -548,14 +604,15 @@ defmodule Code do
   all imports, requires and aliases defined in the current environment
   will be automatically carried over:
 
-      iex> {result, binding} = Code.eval_string("a + b", [a: 1, b: 2], __ENV__)
+      iex> require Integer
+      iex> {result, binding} = Code.eval_string("if Integer.is_odd(a), do: a + b", [a: 1, b: 2], __ENV__)
       iex> result
       3
       iex> Enum.sort(binding)
       [a: 1, b: 2]
 
   """
-  @spec eval_string(List.Chars.t(), binding, Macro.Env.t() | keyword) :: {term, binding}
+  @spec eval_string(List.Chars.t(), binding, Macro.Env.t() | env_eval_opts) :: {term, binding}
   def eval_string(string, binding \\ [], opts \\ [])
 
   def eval_string(string, binding, %Macro.Env{} = env) do
@@ -610,7 +667,8 @@ defmodule Code do
 
   """
   @doc since: "1.15.0"
-  @spec with_diagnostics(keyword(), (-> result)) :: {result, [diagnostic(:warning | :error)]}
+  @spec with_diagnostics([log: boolean()], (-> result)) ::
+          {result, [diagnostic(:warning | :error)]}
         when result: term()
   def with_diagnostics(opts \\ [], fun) do
     value = :erlang.get(:elixir_code_diagnostics)
@@ -643,7 +701,7 @@ defmodule Code do
       Defaults to `true`.
   """
   @doc since: "1.15.0"
-  @spec print_diagnostic(diagnostic(:warning | :error), keyword()) :: :ok
+  @spec print_diagnostic(diagnostic(:warning | :error), snippet: boolean()) :: :ok
   def print_diagnostic(diagnostic, opts \\ []) do
     read_snippet? = Keyword.get(opts, :snippet, true)
     :elixir_errors.print_diagnostic(diagnostic, read_snippet?)
@@ -667,7 +725,7 @@ defmodule Code do
     * `:line` - the line the string starts, used for error reporting
 
     * `:line_length` - the line length to aim for when formatting
-      the document. Defaults to 98. This value indicates when an expression
+      the document. Defaults to `98`. This value indicates when an expression
       should be broken over multiple lines but it is not guaranteed
       to do so. See the "Line length" section below for more information
 
@@ -696,6 +754,14 @@ defmodule Code do
       modifiers, where `<<foo::custom_type>>` becomes `<<foo::custom_type()>>`.
       Defaults to the value of the `:migrate` option. This option changes the AST.
 
+    * `:migrate_call_parens_on_pipe` (since v1.19.0) - when `true`,
+      formats calls on the right-hand side of the pipe operator to always include
+      parentheses, for example `foo |> bar` becomes `foo |> bar()` and
+      `foo |> mod.fun` becomes `foo |> mod.fun()`.
+      Parentheses are always added for qualified calls like `foo |> Bar.bar` even
+      when this option is `false`.
+      Defaults to the value of the `:migrate` option. This option changes the AST.
+
     * `:migrate_charlists_as_sigils` (since v1.18.0) - when `true`,
       formats charlists as [`~c`](`Kernel.sigil_c/2`) sigils, for example
       `'foo'` becomes `~c"foo"`.
@@ -963,12 +1029,18 @@ defmodule Code do
   the code representation (AST). While the formatter can preserve code
   comments between expressions and function arguments, the formatter
   cannot currently preserve them around operators. For example, the following
-  code will move the code comments to before the operator usage:
+  code:
 
       foo() ||
         # also check for bar
         bar()
 
+  will move the code comments to before the operator usage:
+
+      # also check for bar
+      foo() ||
+        bar()
+
   In some situations, code comments can be seen as ambiguous by the formatter.
   For example, the comment in the anonymous function below
 
@@ -1016,9 +1088,9 @@ defmodule Code do
   address the deprecation warnings.
   """
   @doc since: "1.6.0"
-  @spec format_string!(binary, keyword) :: iodata
+  @spec format_string!(binary, [format_opt]) :: iodata
   def format_string!(string, opts \\ []) when is_binary(string) and is_list(opts) do
-    line_length = Keyword.get(opts, :line_length, 98)
+    {line_length, opts} = Keyword.pop(opts, :line_length, 98)
 
     to_quoted_opts =
       [
@@ -1041,7 +1113,7 @@ defmodule Code do
   available options.
   """
   @doc since: "1.6.0"
-  @spec format_file!(binary, keyword) :: iodata
+  @spec format_file!(binary, [format_opt]) :: iodata
   def format_file!(file, opts \\ []) when is_binary(file) and is_list(opts) do
     string = File.read!(file)
     formatted = format_string!(string, [file: file, line: 1] ++ opts)
@@ -1056,7 +1128,8 @@ defmodule Code do
   Macro arguments are typically transformed by unquoting them into the
   returned quoted expressions (instead of evaluated).
 
-  See `eval_string/3` for a description of `binding` and `opts`.
+  See `eval_string/3` for a description of arguments and return types.
+  The options are described under `env_for_eval/1`.
 
   ## Examples
 
@@ -1078,7 +1151,7 @@ defmodule Code do
       [a: 1, b: 2]
 
   """
-  @spec eval_quoted(Macro.t(), binding, Macro.Env.t() | keyword) :: {term, binding}
+  @spec eval_quoted(Macro.t(), binding, Macro.Env.t() | env_eval_opts) :: {term, binding}
   def eval_quoted(quoted, binding \\ [], env_or_opts \\ []) do
     {value, binding, _env} =
       eval_verify(:eval_quoted, [quoted, binding, env_for_eval(env_or_opts)])
@@ -1109,8 +1182,15 @@ defmodule Code do
     * `:line` - the line on which the script starts
 
     * `:module` - the module to run the environment on
+
+    * `:prune_binding` - (since v1.14.2) prune binding to keep only
+      variables read or written by the evaluated code. Note that
+      variables used by modules are always pruned, even if later used
+      by the modules. You can submit to the `:on_module` tracer event
+      and access the variables used by the module from its environment.
   """
   @doc since: "1.14.0"
+  @spec env_for_eval(Macro.Env.t() | env_eval_opts) :: Macro.Env.t()
   def env_for_eval(env_or_opts), do: :elixir.env_for_eval(env_or_opts)
 
   @doc """
@@ -1124,15 +1204,11 @@ defmodule Code do
 
   ## Options
 
-    * `:prune_binding` - (since v1.14.2) prune binding to keep only
-      variables read or written by the evaluated code. Note that
-      variables used by modules are always pruned, even if later used
-      by the modules. You can submit to the `:on_module` tracer event
-      and access the variables used by the module from its environment.
+  It accepts the same options as `env_for_eval/1`.
 
   """
   @doc since: "1.14.0"
-  @spec eval_quoted_with_env(Macro.t(), binding, Macro.Env.t(), keyword) ::
+  @spec eval_quoted_with_env(Macro.t(), binding, Macro.Env.t(), env_eval_opts) ::
           {term, binding, Macro.Env.t()}
   def eval_quoted_with_env(quoted, binding, %Macro.Env{} = env, opts \\ [])
       when is_list(binding) do
@@ -1151,10 +1227,14 @@ defmodule Code do
       Defaults to `"nofile"`.
 
     * `:line` - the starting line of the string being parsed.
-      Defaults to 1.
+      Defaults to `1`.
 
     * `:column` - (since v1.11.0) the starting column of the string being parsed.
-      Defaults to 1.
+      Defaults to `1`.
+
+    * `:indentation` - (since v1.19.0) the indentation for the string being parsed.
+      This is useful when the code parsed is embedded within another document.
+      Defaults to `0`.
 
     * `:columns` - when `true`, attach a `:column` key to the quoted
       metadata. Defaults to `false`.
@@ -1230,8 +1310,16 @@ defmodule Code do
     * atoms used to represent single-letter sigils like `:sigil_X`
       (but multi-letter sigils like `:sigil_XYZ` are encoded).
 
+  ## Examples
+
+      iex> Code.string_to_quoted("1 + 3")
+      {:ok, {:+, [line: 1], [1, 3]}}
+
+      iex> Code.string_to_quoted("1 \ 3")
+      {:error, {[line: 1, column: 4], "syntax error before: ", "\"3\""}}
+
   """
-  @spec string_to_quoted(List.Chars.t(), keyword) ::
+  @spec string_to_quoted(List.Chars.t(), parser_opts) ::
           {:ok, Macro.t()} | {:error, {location :: keyword, binary | {binary, binary}, binary}}
   def string_to_quoted(string, opts \\ []) when is_list(opts) do
     file = Keyword.get(opts, :file, "nofile")
@@ -1258,7 +1346,7 @@ defmodule Code do
 
   Check `string_to_quoted/2` for options information.
   """
-  @spec string_to_quoted!(List.Chars.t(), keyword) :: Macro.t()
+  @spec string_to_quoted!(List.Chars.t(), parser_opts) :: Macro.t()
   def string_to_quoted!(string, opts \\ []) when is_list(opts) do
     file = Keyword.get(opts, :file, "nofile")
     line = Keyword.get(opts, :line, 1)
@@ -1309,7 +1397,7 @@ defmodule Code do
 
   """
   @doc since: "1.13.0"
-  @spec string_to_quoted_with_comments(List.Chars.t(), keyword) ::
+  @spec string_to_quoted_with_comments(List.Chars.t(), parser_opts) ::
           {:ok, Macro.t(), list(map())} | {:error, {location :: keyword, term, term}}
   def string_to_quoted_with_comments(string, opts \\ []) when is_list(opts) do
     charlist = to_charlist(string)
@@ -1339,7 +1427,7 @@ defmodule Code do
   Check `string_to_quoted/2` for options information.
   """
   @doc since: "1.13.0"
-  @spec string_to_quoted_with_comments!(List.Chars.t(), keyword) :: {Macro.t(), list(map())}
+  @spec string_to_quoted_with_comments!(List.Chars.t(), parser_opts) :: {Macro.t(), list(map())}
   def string_to_quoted_with_comments!(string, opts \\ []) do
     charlist = to_charlist(string)
 
@@ -1348,13 +1436,11 @@ defmodule Code do
         {forms, comments}
 
       {:error, {location, error, token}} ->
-        :elixir_errors.parse_error(
-          location,
-          Keyword.get(opts, :file, "nofile"),
-          error,
-          token,
-          {charlist, Keyword.get(opts, :line, 1), Keyword.get(opts, :column, 1)}
-        )
+        file = Keyword.get(opts, :file, "nofile")
+        line = Keyword.get(opts, :line, 1)
+        column = Keyword.get(opts, :column, 1)
+        input = {charlist, line, column, Keyword.get(opts, :indentation, 0)}
+        :elixir_errors.parse_error(location, file, error, token, input)
     end
   end
 
@@ -1364,7 +1450,7 @@ defmodule Code do
     comment = %{
       line: line,
       column: column,
-      previous_eol_count: previous_eol_count(tokens),
+      previous_eol_count: min(previous_eol_count(tokens), last_comment_distance(comments, line)),
       next_eol_count: next_eol_count(rest, 0),
       text: List.to_string(comment)
     }
@@ -1378,6 +1464,9 @@ defmodule Code do
   defp next_eol_count([?\r, ?\n | rest], count), do: next_eol_count(rest, count + 1)
   defp next_eol_count(_, count), do: count
 
+  defp last_comment_distance([%{line: last_line} | _], line), do: line - last_line
+  defp last_comment_distance([], _line), do: :infinity
+
   defp previous_eol_count([{token, {_, _, count}} | _])
        when token in [:eol, :",", :";"] and count > 0 do
     count
@@ -1423,6 +1512,9 @@ defmodule Code do
 
   ## Options
 
+  This function accepts all options supported by `format_string!/2` for controlling
+  code formatting, plus these additional options:
+
     * `:comments` - the list of comments associated with the quoted expression.
       Defaults to `[]`. It is recommended that both `:token_metadata` and
       `:literal_encoder` options are given to `string_to_quoted_with_comments/2`
@@ -1433,17 +1525,13 @@ defmodule Code do
       `string_to_quoted/2`, setting this option to `false` will prevent it from
       escaping the sequences twice. Defaults to `true`.
 
-    * `:locals_without_parens` - a keyword list of name and arity
-      pairs that should be kept without parens whenever possible.
-      The arity may be the atom `:*`, which implies all arities of
-      that name. The formatter already includes a list of functions
-      and this option augments this list.
-
-    * `:syntax_colors` - a keyword list of colors the output is colorized.
-      See `Inspect.Opts` for more information.
+  See `format_string!/2` for the full list of formatting options including
+  `:file`, `:line`, `:line_length`, `:locals_without_parens`, `:force_do_end_blocks`,
+  `:syntax_colors`, and all migration options like `:migrate_charlists_as_sigils`.
   """
   @doc since: "1.13.0"
-  @spec quoted_to_algebra(Macro.t(), keyword) :: Inspect.Algebra.t()
+  @spec quoted_to_algebra(Macro.t(), [format_opt() | quoted_to_algebra_opt()]) ::
+          Inspect.Algebra.t()
   def quoted_to_algebra(quoted, opts \\ []) do
     quoted
     |> Code.Normalizer.normalize(opts)
@@ -1563,7 +1651,7 @@ defmodule Code do
   ## Examples
 
       Code.compiler_options(infer_signatures: false)
-      #=> %{infer_signatures: true}
+      #=> %{infer_signatures: [:elixir]}
 
   """
   @spec compiler_options(Enumerable.t({atom, term})) :: %{optional(atom) => term}
@@ -1647,14 +1735,16 @@ defmodule Code do
     * `:ignore_module_conflict` - when `true`, does not warn when a module has
       already been defined. Defaults to `false`.
 
-    * `:infer_signatures` (since v1.18.0) - when `false`, it disables module-local
+    * `:infer_signatures` (since v1.18.0) - a list of applications of which modules
+      should be using during type inference. When `false`, it disables module-local
       signature inference used when type checking remote calls to the compiled
       module. Type checking will be executed regardless of the value of this option.
-      Defaults to `true`.
+      Defaults to `true`, which is equivalent to setting it to `[:elixir]` only.
 
-      `mix test` automatically disables this option via the `:test_elixirc_options`
-      project configuration, as there is typically no need to store infer signatures
-      for test files.
+      When setting this option, we recommend running `mix clean` so the current module
+      may be compiled from scratch. `mix test` automatically disables this option via
+      the `:test_elixirc_options` project configuration, as there is typically no need
+      to infer signatures for test files.
 
     * `:relative_paths` - when `true`, uses relative paths in quoted nodes,
       warnings, and errors generated by the compiler. Note disabling this option
@@ -1705,28 +1795,6 @@ defmodule Code do
     :ok
   end
 
-  # TODO: Remove me in Elixir v2.0
-  def put_compiler_option(:warnings_as_errors, _value) do
-    IO.warn(
-      ":warnings_as_errors is deprecated as part of Code.put_compiler_option/2, " <>
-        "instead you must pass it as a --warnings-as-errors flag. " <>
-        "If you need to set it as a default in a mix task, you can also set it under aliases: " <>
-        "[compile: \"compile --warnings-as-errors\"]"
-    )
-
-    :ok
-  end
-
-  def put_compiler_option(:no_warn_undefined, value) do
-    if value != :all and not is_list(value) do
-      raise "compiler option :no_warn_undefined should be a list or the atom :all, " <>
-              "got: #{inspect(value)}"
-    end
-
-    :elixir_config.put(:no_warn_undefined, value)
-    :ok
-  end
-
   def put_compiler_option(key, value) when key in @list_compiler_options do
     if not is_list(value) do
       raise "compiler option #{inspect(key)} should be a list, got: #{inspect(value)}"
@@ -1746,9 +1814,61 @@ defmodule Code do
     :ok
   end
 
-  # TODO: Remove this option on Elixir v2.0
-  # TODO: Warn if mode is :warn on Elixir v1.19
+  def put_compiler_option(:infer_signatures, value) do
+    value =
+      cond do
+        value == false ->
+          false
+
+        value == true ->
+          [:elixir]
+
+        is_list(value) and Enum.all?(value, &is_atom/1) ->
+          value
+
+        true ->
+          raise "compiler option :infer_signatures should be a boolean or a list of applications, got: #{inspect(value)}"
+      end
+
+    :elixir_config.put(:infer_signatures, value)
+    :ok
+  end
+
+  def put_compiler_option(:no_warn_undefined, value) do
+    if value != :all and not is_list(value) do
+      raise "compiler option :no_warn_undefined should be a list or the atom :all, " <>
+              "got: #{inspect(value)}"
+    end
+
+    :elixir_config.put(:no_warn_undefined, value)
+    :ok
+  end
+
+  # TODO: Remove me in Elixir v2.0
+  def put_compiler_option(:warnings_as_errors, _value) do
+    IO.warn(
+      ":warnings_as_errors is deprecated as part of Code.put_compiler_option/2, " <>
+        "instead you must pass it as a --warnings-as-errors flag. " <>
+        "If you need to set it as a default in a mix task, you can also set it under aliases: " <>
+        "[compile: \"compile --warnings-as-errors\"]"
+    )
+
+    :ok
+  end
+
+  # TODO: Remove me in Elixir v2.0
   def put_compiler_option(:on_undefined_variable, value) when value in [:raise, :warn] do
+    if value == :warn do
+      IO.warn_once(
+        {__MODULE__, :on_undefined_variable},
+        fn ->
+          "setting :on_undefined_variable to :warn is deprecated. " <>
+            "The warning behaviour will be removed in future releases"
+        end,
+        3
+      )
+    end
+
     :elixir_config.put(:on_undefined_variable, value)
     :ok
   end
@@ -2013,7 +2133,7 @@ defmodule Code do
     case :code.ensure_loaded(module) do
       {:error, :nofile} = error ->
         if can_await_module_compilation?() do
-          case Kernel.ErrorHandler.ensure_compiled(module, :module, mode) do
+          case Kernel.ErrorHandler.ensure_compiled(module, :module, mode, nil) do
             :found -> {:module, module}
             :deadlock -> {:error, :unavailable}
             :not_found -> {:error, :nofile}
@@ -2035,7 +2155,7 @@ defmodule Code do
 
   ## Examples
 
-      iex> Code.loaded?(Atom)
+      iex> Code.loaded?(String)
       true
 
       iex> Code.loaded?(NotYetLoaded)

lib/elixir/lib/code/formatter.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Code.Formatter do
   @moduledoc false
   import Inspect.Algebra, except: [format: 2, surround: 3, surround: 4]
@@ -154,6 +158,7 @@ defmodule Code.Formatter do
   @doc """
   Converts the quoted expression into an algebra document.
   """
+  @spec to_algebra(Macro.t(), keyword()) :: Inspect.Algebra.t()
   def to_algebra(quoted, opts \\ []) do
     comments = Keyword.get(opts, :comments, [])
 
@@ -191,6 +196,7 @@ defmodule Code.Formatter do
     sigils = Keyword.get(opts, :sigils, [])
     migrate = Keyword.get(opts, :migrate, false)
     migrate_bitstring_modifiers = Keyword.get(opts, :migrate_bitstring_modifiers, migrate)
+    migrate_call_parens_on_pipe = Keyword.get(opts, :migrate_call_parens_on_pipe, migrate)
     migrate_charlists_as_sigils = Keyword.get(opts, :migrate_charlists_as_sigils, migrate)
     migrate_unless = Keyword.get(opts, :migrate_unless, migrate)
     syntax_colors = Keyword.get(opts, :syntax_colors, [])
@@ -218,6 +224,7 @@ defmodule Code.Formatter do
       sigils: sigils,
       file: file,
       migrate_bitstring_modifiers: migrate_bitstring_modifiers,
+      migrate_call_parens_on_pipe: migrate_call_parens_on_pipe,
       migrate_charlists_as_sigils: migrate_charlists_as_sigils,
       migrate_unless: migrate_unless,
       inspect_opts: %Inspect.Opts{syntax_colors: syntax_colors}
@@ -487,7 +494,16 @@ defmodule Code.Formatter do
     binary_op_to_algebra(:in, "not in", meta, left, right, context, state)
   end
 
-  # disable migrate_unless within defmacro
+  # disable migrate_call_parens_on_pipe within defmacro
+  defp quoted_to_algebra(
+         {atom, _, [{:|>, _, _}, _]} = ast,
+         context,
+         %{migrate_call_parens_on_pipe: true} = state
+       )
+       when atom in [:defmacro, :defmacrop] do
+    quoted_to_algebra(ast, context, %{state | migrate_call_parens_on_pipe: false})
+  end
+
   defp quoted_to_algebra(
          {atom, _, [{:unless, _, _}, _]} = ast,
          context,
@@ -602,9 +618,12 @@ defmodule Code.Formatter do
       end
 
     doc =
-      with_next_break_fits(next_break_fits?(right_arg, state), right, fn right ->
-        concat(group(left), group(nest(glue(op, group(right)), 2, :break)))
-      end)
+      concat(
+        group(left),
+        with_next_break_fits(next_break_fits?(right_arg, state), right, fn right ->
+          nest(glue(op, right), 2, :break)
+        end)
+      )
 
     {doc, state}
   end
@@ -787,15 +806,13 @@ defmodule Code.Formatter do
     {right, state} =
       binary_operand_to_algebra(right_arg, right_context, state, op, op_info, :right, 0)
 
-    doc =
+    {op_string, right} =
       cond do
         op in @no_space_binary_operators ->
-          op_doc = color_doc(op_string, :operator, state.inspect_opts)
-          concat(concat(group(left), op_doc), group(right))
+          {op_string, group(right)}
 
         op in @no_newline_binary_operators ->
-          op_doc = color_doc(" " <> op_string <> " ", :operator, state.inspect_opts)
-          concat(concat(group(left), op_doc), group(right))
+          {" " <> op_string <> " ", group(right)}
 
         true ->
           eol? = eol?(meta, state)
@@ -803,14 +820,15 @@ defmodule Code.Formatter do
           next_break_fits? =
             op in @next_break_fits_operators and next_break_fits?(right_arg, state) and not eol?
 
-          with_next_break_fits(next_break_fits?, right, fn right ->
-            op_doc = color_doc(" " <> op_string, :operator, state.inspect_opts)
-            right = nest(glue(op_doc, group(right)), nesting, :break)
-            right = if eol?, do: force_unfit(right), else: right
-            concat(group(left), group(right))
-          end)
+          {" " <> op_string,
+           with_next_break_fits(next_break_fits?, right, fn right ->
+             right = nest(concat(break(), right), nesting, :break)
+             if eol?, do: force_unfit(right), else: right
+           end)}
       end
 
+    op_doc = color_doc(op_string, :operator, state.inspect_opts)
+    doc = concat(concat(group(left), op_doc), group(right))
     {doc, state}
   end
 
@@ -832,6 +850,38 @@ defmodule Code.Formatter do
     {wrap_in_parens(doc), state}
   end
 
+  # |> var
+  # |> var()
+  defp binary_operand_to_algebra(
+         {var, meta, var_context},
+         context,
+         %{migrate_call_parens_on_pipe: true} = state,
+         :|>,
+         _parent_info,
+         :right,
+         _nesting
+       )
+       when is_atom(var) and is_atom(var_context) do
+    operand = {var, meta, []}
+    quoted_to_algebra(operand, context, state)
+  end
+
+  # |> var.fun
+  # |> var.fun()
+  defp binary_operand_to_algebra(
+         {{:., _, [_, fun]} = call, meta, []},
+         context,
+         %{migrate_call_parens_on_pipe: true} = state,
+         :|>,
+         _parent_info,
+         :right,
+         _nesting
+       )
+       when is_atom(fun) do
+    meta = Keyword.put_new_lazy(meta, :closing, fn -> [line: meta[:line]] end)
+    quoted_to_algebra({call, meta, []}, context, state)
+  end
+
   defp binary_operand_to_algebra(operand, context, state, parent_op, parent_info, side, nesting) do
     {parent_assoc, parent_prec} = parent_info
 
@@ -1215,7 +1265,7 @@ defmodule Code.Formatter do
         args_doc =
           if skip_parens? do
             left_doc
-            |> concat(next_break_fits(group(right_doc, :inherit), :enabled))
+            |> concat(group(right_doc, :optimistic))
             |> nest(:cursor, :break)
           else
             right_doc =
@@ -1223,8 +1273,7 @@ defmodule Code.Formatter do
               |> nest(2, :break)
               |> concat(break(""))
               |> concat(")")
-              |> group(:inherit)
-              |> next_break_fits(:enabled)
+              |> group(:optimistic)
 
             concat(nest(left_doc, 2, :break), right_doc)
           end
@@ -1267,13 +1316,11 @@ defmodule Code.Formatter do
           |> concat(args_doc)
           |> nest(2)
           |> concat(extra)
-          |> group()
 
         skip_parens? ->
           " "
           |> concat(args_doc)
           |> concat(extra)
-          |> group()
 
         true ->
           "("
@@ -1281,13 +1328,12 @@ defmodule Code.Formatter do
           |> nest(2, :break)
           |> concat(args_doc)
           |> concat(extra)
-          |> group()
       end
 
     if next_break_fits? do
-      {next_break_fits(doc, :disabled), state}
+      {group(doc, :pessimistic), state}
     else
-      {doc, state}
+      {group(doc), state}
     end
   end
 
@@ -1753,10 +1799,17 @@ defmodule Code.Formatter do
 
       doc =
         case args do
-          [_ | _] -> concat_to_last_group(doc, ",")
-          [] when last_arg_mode == :force_comma -> concat_to_last_group(doc, ",")
-          [] when last_arg_mode == :next_break_fits -> next_break_fits(doc, :enabled)
-          [] when last_arg_mode == :none -> doc
+          [_ | _] ->
+            concat_to_last_group(doc, ",")
+
+          [] when last_arg_mode == :force_comma ->
+            concat_to_last_group(doc, ",")
+
+          [] when last_arg_mode == :next_break_fits ->
+            doc |> ungroup_if_group() |> group(:optimistic)
+
+          [] when last_arg_mode == :none ->
+            doc
         end
 
       {{doc, @empty, 1}, state}
@@ -2274,11 +2327,14 @@ defmodule Code.Formatter do
   defp with_next_break_fits(condition, doc, fun) do
     if condition do
       doc
-      |> next_break_fits(:enabled)
+      |> group(:optimistic)
       |> fun.()
-      |> next_break_fits(:disabled)
+      |> group(:pessimistic)
     else
-      fun.(doc)
+      doc
+      |> group()
+      |> fun.()
+      |> group()
     end
   end
 
@@ -2445,16 +2501,16 @@ defmodule Code.Formatter do
 
   # Relying on the inner document is brittle and error prone.
   # It would be best if we had a mechanism to apply this.
-  defp concat_to_last_group({:doc_cons, left, right}, concat) do
-    {:doc_cons, left, concat_to_last_group(right, concat)}
+  defp concat_to_last_group([left | right], concat) do
+    [left | concat_to_last_group(right, concat)]
   end
 
   defp concat_to_last_group({:doc_group, group, mode}, concat) do
-    {:doc_group, {:doc_cons, group, concat}, mode}
+    {:doc_group, concat(group, concat), mode}
   end
 
   defp concat_to_last_group(other, concat) do
-    {:doc_cons, other, concat}
+    concat(other, concat)
   end
 
   defp ungroup_if_group({:doc_group, group, _mode}), do: group

lib/elixir/lib/code/fragment.ex

@@ -1,3 +1,6 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
 defmodule Code.Fragment do
   @moduledoc """
   This module provides conveniences for analyzing fragments of
@@ -8,6 +11,59 @@ defmodule Code.Fragment do
 
   @type position :: {line :: pos_integer(), column :: pos_integer()}
 
+  @typedoc """
+  Options for cursor context functions.
+
+  Currently, these options are not used but reserved for future extensibility.
+  """
+  @type cursor_opts :: []
+
+  @typedoc """
+  Options for converting code fragments to quoted expressions.
+  """
+  @type container_cursor_to_quoted_opts :: [
+          file: String.t(),
+          line: pos_integer(),
+          column: pos_integer(),
+          columns: boolean(),
+          token_metadata: boolean(),
+          literal_encoder: (term(), Macro.metadata() -> term()),
+          trailing_fragment: String.t()
+        ]
+
+  @doc ~S"""
+  Returns the list of lines in the given string, preserving their line endings.
+
+  Only the line endings recognized by the Elixir compiler are
+  considered, namely `\r\n` and `\n`. If you would like the retrieve
+  lines without their line endings, use `String.split(string, ["\r\n", "\n"])`.
+
+  ## Examples
+
+      iex> Code.Fragment.lines("foo\r\nbar\r\nbaz")
+      ["foo\r\n", "bar\r\n", "baz"]
+
+      iex> Code.Fragment.lines("foo\nbar\nbaz")
+      ["foo\n", "bar\n", "baz"]
+
+      iex> Code.Fragment.lines("")
+      [""]
+
+  """
+  @doc since: "1.19.0"
+  def lines(string) do
+    lines(string, <<>>)
+  end
+
+  defp lines(<<?\n, rest::binary>>, acc),
+    do: [<<acc::binary, ?\n>> | lines(rest, <<>>)]
+
+  defp lines(<<char, rest::binary>>, acc),
+    do: lines(rest, <<acc::binary, char>>)
+
+  defp lines(<<>>, acc),
+    do: [acc]
+
   @doc """
   Receives a string and returns the cursor context.
 
@@ -43,6 +99,9 @@ defmodule Code.Fragment do
       or `{:local_or_var, charlist}` and `charlist` is a static part
       Examples are `__MODULE__.Submodule` or `@hello.Submodule`
 
+    * `{:block_keyword_or_binary_operator, charlist}` - may be a block keyword (do, end, after,
+      catch, else, rescue) or a binary operator
+
     * `{:dot, inside_dot, charlist}` - the context is a dot
       where `inside_dot` is either a `{:var, charlist}`, `{:alias, charlist}`,
       `{:module_attribute, charlist}`, `{:unquoted_atom, charlist}` or a `dot`
@@ -133,9 +192,10 @@ defmodule Code.Fragment do
   references, and more.
   """
   @doc since: "1.13.0"
-  @spec cursor_context(List.Chars.t(), keyword()) ::
+  @spec cursor_context(List.Chars.t(), cursor_opts()) ::
           {:alias, charlist}
           | {:alias, inside_alias, charlist}
+          | {:block_keyword_or_binary_operator, charlist}
           | {:dot, inside_dot, charlist}
           | {:dot_arity, inside_dot, charlist}
           | {:dot_call, inside_dot, charlist}
@@ -185,15 +245,15 @@ defmodule Code.Fragment do
     cursor_context(to_charlist(other), opts)
   end
 
-  @operators ~c"\\<>+-*/:=|&~^%!"
-  @starter_punctuation ~c",([{;"
-  @non_starter_punctuation ~c")]}\"'.$"
+  @operators ~c"\\<>+-*/:=|&~^%!$"
+  @starting_punctuation ~c",([{;"
+  @closing_punctuation ~c")]}\"'"
   @space ~c"\t\s"
   @trailing_identifier ~c"?!"
   @tilde_op_prefix ~c"<=~"
 
   @non_identifier @trailing_identifier ++
-                    @operators ++ @starter_punctuation ++ @non_starter_punctuation ++ @space
+                    @operators ++ @starting_punctuation ++ @closing_punctuation ++ @space ++ [?.]
 
   @textual_operators ~w(when not and or in)c
   @keywords ~w(do end after else catch rescue fn true false nil)c
@@ -223,11 +283,11 @@ defmodule Code.Fragment do
       # A local arity definition
       [?/ | rest] -> arity_to_cursor_context(strip_spaces(rest, spaces + 1))
       # Starting a new expression
-      [h | _] when h in @starter_punctuation -> {:expr, 0}
-      # It is a local or remote call without parens
-      rest when spaces > 0 -> call_to_cursor_context({rest, spaces})
+      [h | _] when h in @starting_punctuation -> {:expr, 0}
+      # It is keyword, binary operator, a local or remote call without parens
+      rest when spaces > 0 -> closing_or_call_to_cursor_context({rest, spaces})
       # It is an identifier
-      _ -> identifier_to_cursor_context(reverse, 0, false)
+      _ -> identifier_to_cursor_context(reverse, spaces, false)
     end
   end
 
@@ -242,7 +302,8 @@ defmodule Code.Fragment do
       {{:local_or_var, acc}, count} -> {{:local_arity, acc}, count}
       {{:dot, base, acc}, count} -> {{:dot_arity, base, acc}, count}
       {{:operator, acc}, count} -> {{:operator_arity, acc}, count}
-      {_, _} -> {:none, 0}
+      {{:sigil, _}, _} -> {:none, 0}
+      {_, _} -> {{:operator, ~c"/"}, 1}
     end
   end
 
@@ -266,8 +327,16 @@ defmodule Code.Fragment do
     end
   end
 
+  defp closing_or_call_to_cursor_context({reverse, spaces}) do
+    if closing?(reverse) do
+      {{:block_keyword_or_binary_operator, ~c""}, 0}
+    else
+      call_to_cursor_context({reverse, spaces})
+    end
+  end
+
   defp identifier_to_cursor_context([?., ?., ?: | _], n, _), do: {{:unquoted_atom, ~c".."}, n + 3}
-  defp identifier_to_cursor_context([?., ?., ?. | _], n, _), do: {{:local_or_var, ~c"..."}, n + 3}
+  defp identifier_to_cursor_context([?., ?., ?. | _], n, _), do: {{:operator, ~c"..."}, n + 3}
   defp identifier_to_cursor_context([?., ?: | _], n, _), do: {{:unquoted_atom, ~c"."}, n + 2}
   defp identifier_to_cursor_context([?., ?. | _], n, _), do: {{:operator, ~c".."}, n + 2}
 
@@ -317,8 +386,13 @@ defmodule Code.Fragment do
           {~c"." ++ rest, count} when rest == [] or hd(rest) != ?. ->
             dot(rest, count + 1, acc)
 
-          _ ->
-            {{:local_or_var, acc}, count}
+          {rest, rest_count} ->
+            response =
+              if rest_count > count and closing?(rest),
+                do: :block_keyword_or_binary_operator,
+                else: :local_or_var
+
+            {{response, acc}, count}
         end
 
       {:capture_arg, acc, count} ->
@@ -326,6 +400,28 @@ defmodule Code.Fragment do
     end
   end
 
+  # If it is a closing punctuation
+  defp closing?([h | _]) when h in @closing_punctuation, do: true
+  # Closing bitstring (but deal with operators)
+  defp closing?([?>, ?> | rest]), do: rest == [] or hd(rest) not in [?>, ?~]
+  # Keywords
+  defp closing?(rest) do
+    case split_non_identifier(rest, []) do
+      {~c"nil", _} -> true
+      {~c"true", _} -> true
+      {~c"false", _} -> true
+      {[digit | _], _} when digit in ?0..?9 -> true
+      {[upper | _], _} when upper in ?A..?Z -> true
+      {[_ | _], [?: | rest]} -> rest == [] or hd(rest) != ?:
+      {_, _} -> false
+    end
+  end
+
+  defp split_non_identifier([h | t], acc) when h not in @non_identifier,
+    do: split_non_identifier(t, [h | acc])
+
+  defp split_non_identifier(rest, acc), do: {acc, rest}
+
   defp identifier([?? | rest], count), do: check_identifier(rest, count + 1, [??])
   defp identifier([?! | rest], count), do: check_identifier(rest, count + 1, [?!])
   defp identifier(rest, count), do: check_identifier(rest, count, [])
@@ -587,7 +683,7 @@ defmodule Code.Fragment do
   of examples and their return values.
   """
   @doc since: "1.13.0"
-  @spec surround_context(List.Chars.t(), position(), keyword()) ::
+  @spec surround_context(List.Chars.t(), position(), cursor_opts()) ::
           %{begin: position, end: position, context: context} | :none
         when context:
                {:alias, charlist}
@@ -696,6 +792,12 @@ defmodule Code.Fragment do
           {{:local_or_var, acc}, offset} ->
             build_surround({:local_or_var, acc}, reversed, line, offset)
 
+          {{:block_keyword_or_binary_operator, acc}, offset} when acc in @textual_operators ->
+            build_surround({:operator, acc}, reversed, line, offset)
+
+          {{:block_keyword_or_binary_operator, acc}, offset} when acc in @keywords ->
+            build_surround({:keyword, acc}, reversed, line, offset)
+
           {{:module_attribute, ~c""}, offset} ->
             build_surround({:operator, ~c"@"}, reversed, line, offset)
 
@@ -1112,10 +1214,10 @@ defmodule Code.Fragment do
       Defaults to `"nofile"`.
 
     * `:line` - the starting line of the string being parsed.
-      Defaults to 1.
+      Defaults to `1`.
 
     * `:column` - the starting column of the string being parsed.
-      Defaults to 1.
+      Defaults to `1`.
 
     * `:columns` - when `true`, attach a `:column` key to the quoted
       metadata. Defaults to `false`.
@@ -1134,7 +1236,7 @@ defmodule Code.Fragment do
 
   """
   @doc since: "1.13.0"
-  @spec container_cursor_to_quoted(List.Chars.t(), keyword()) ::
+  @spec container_cursor_to_quoted(List.Chars.t(), container_cursor_to_quoted_opts()) ::
           {:ok, Macro.t()} | {:error, {location :: keyword, binary | {binary, binary}, binary}}
   def container_cursor_to_quoted(fragment, opts \\ []) do
     {trailing_fragment, opts} = Keyword.pop(opts, :trailing_fragment)
@@ -1230,7 +1332,7 @@ defmodule Code.Fragment do
   defp drop_tokens([{:do, _} | tokens], counter), do: drop_tokens(tokens, counter + 1)
 
   defp drop_tokens([_ | tokens], counter), do: drop_tokens(tokens, counter)
-  defp drop_tokens([], 0), do: []
+  defp drop_tokens([], _counter), do: []
 
   defp maybe_missing_stab?([{:after, _} | _], _stab_choice?), do: true
   defp maybe_missing_stab?([{:do, _} | _], _stab_choice?), do: true

lib/elixir/lib/code/identifier.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Code.Identifier do
   @moduledoc false
 

lib/elixir/lib/code/normalizer.ex

@@ -1,3 +1,6 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
 defmodule Code.Normalizer do
   @moduledoc false
 
@@ -11,6 +14,7 @@ defmodule Code.Normalizer do
   Wraps literals in the quoted expression to conform to the AST format expected
   by the formatter.
   """
+  @spec normalize(Macro.t(), keyword()) :: Macro.t()
   def normalize(quoted, opts \\ []) do
     line = Keyword.get(opts, :line, nil)
     escape = Keyword.get(opts, :escape, true)

lib/elixir/lib/code/typespec.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Code.Typespec do
   @moduledoc false
 

lib/elixir/lib/collectable.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defprotocol Collectable do
   @moduledoc """
   A protocol to traverse data structures.

lib/elixir/lib/config.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Config do
   @moduledoc ~S"""
   A simple keyword-based configuration API.
@@ -94,6 +98,12 @@ defmodule Config do
   (assembled with `mix release`).
   """
 
+  @type config_opts :: [
+          imports: [Path.t()] | :disabled,
+          env: atom(),
+          target: atom()
+        ]
+
   @opts_key {__MODULE__, :opts}
   @config_key {__MODULE__, :config}
   @imports_key {__MODULE__, :imports}
@@ -131,7 +141,6 @@ defmodule Config do
 
       config :logger,
         level: :warn,
-        backends: [:console]
 
       config :logger,
         level: :info,
@@ -139,7 +148,7 @@ defmodule Config do
 
   will have a final configuration for `:logger` of:
 
-      [level: :info, backends: [:console], truncate: 1024]
+      [level: :info, truncate: 1024]
 
   """
   @doc since: "1.9.0"
@@ -224,7 +233,8 @@ defmodule Config do
   Returns the environment this configuration file is executed on.
 
   In Mix projects this function returns the environment this configuration
-  file is executed on. In releases, the environment when `mix release` ran.
+  file is executed on. 
+  In releases, returns the `MIX_ENV` specified when running `mix release`.
 
   This is most often used to execute conditional code:
 
@@ -302,7 +312,7 @@ defmodule Config do
   end
 
   @doc false
-  @spec __eval__!(Path.t(), binary(), keyword) :: {keyword, [Path.t()] | :disabled}
+  @spec __eval__!(Path.t(), binary(), config_opts) :: {keyword, [Path.t()] | :disabled}
   def __eval__!(file, content, opts \\ []) when is_binary(file) and is_list(opts) do
     env = Keyword.get(opts, :env)
     target = Keyword.get(opts, :target)

lib/elixir/lib/config/provider.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Config.Provider do
   @moduledoc """
   Specifies a provider API that loads configuration during boot.
@@ -107,6 +111,16 @@ defmodule Config.Provider do
   """
   @type config_path :: {:system, binary(), binary()} | binary()
 
+  @typedoc """
+  Options for `init/3`.
+  """
+  @type init_opts :: [
+          extra_config: config(),
+          prune_runtime_sys_config_after_boot: boolean(),
+          reboot_system_after_config: boolean(),
+          validate_compile_env: [{atom(), [atom()], term()}]
+        ]
+
   @doc """
   Invoked when initializing a config provider.
 
@@ -192,6 +206,7 @@ defmodule Config.Provider do
   @reboot_mode_key :config_provider_reboot_mode
 
   @doc false
+  @spec init([{module(), term()}], config_path(), init_opts()) :: config()
   def init(providers, config_path, opts \\ []) when is_list(providers) and is_list(opts) do
     validate_config_path!(config_path)
     providers = for {provider, init} <- providers, do: {provider, provider.init(init)}

lib/elixir/lib/config/reader.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Config.Reader do
   @moduledoc """
   API for reading config files defined with `Config`.
@@ -42,6 +46,12 @@ defmodule Config.Reader do
 
   @behaviour Config.Provider
 
+  @type config_opts :: [
+          imports: [Path.t()] | :disabled,
+          env: atom(),
+          target: atom()
+        ]
+
   @impl true
   def init(opts) when is_list(opts) do
     {path, opts} = Keyword.pop!(opts, :path)
@@ -64,7 +74,7 @@ defmodule Config.Reader do
   Accepts the same options as `read!/2`.
   """
   @doc since: "1.11.0"
-  @spec eval!(Path.t(), binary, keyword) :: keyword
+  @spec eval!(Path.t(), binary, config_opts) :: keyword
   def eval!(file, contents, opts \\ [])
       when is_binary(file) and is_binary(contents) and is_list(opts) do
     Config.__eval__!(Path.expand(file), contents, opts) |> elem(0)
@@ -86,7 +96,7 @@ defmodule Config.Reader do
 
   """
   @doc since: "1.9.0"
-  @spec read!(Path.t(), keyword) :: keyword
+  @spec read!(Path.t(), config_opts) :: keyword
   def read!(file, opts \\ []) when is_binary(file) and is_list(opts) do
     file = Path.expand(file)
     Config.__eval__!(file, File.read!(file), opts) |> elem(0)
@@ -100,7 +110,7 @@ defmodule Config.Reader do
   option cannot be disabled in `read_imports!/2`.
   """
   @doc since: "1.9.0"
-  @spec read_imports!(Path.t(), keyword) :: {keyword, [Path.t()]}
+  @spec read_imports!(Path.t(), config_opts) :: {keyword, [Path.t()]}
   def read_imports!(file, opts \\ []) when is_binary(file) and is_list(opts) do
     if opts[:imports] == :disabled do
       raise ArgumentError, ":imports must be a list of paths"

lib/elixir/lib/dict.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Dict do
   @moduledoc ~S"""
   Generic API for dictionaries.

lib/elixir/lib/dynamic_supervisor.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule DynamicSupervisor do
   @moduledoc ~S"""
   A supervisor optimized to only start children dynamically.
@@ -133,67 +137,6 @@ defmodule DynamicSupervisor do
 
   A supervisor is bound to the same name registration rules as a `GenServer`.
   Read more about these rules in the documentation for `GenServer`.
-
-  ## Migrating from Supervisor's :simple_one_for_one
-
-  In case you were using the deprecated `:simple_one_for_one` strategy from
-  the `Supervisor` module, you can migrate to the `DynamicSupervisor` in
-  few steps.
-
-  Imagine the given "old" code:
-
-      defmodule MySupervisor do
-        use Supervisor
-
-        def start_link(init_arg) do
-          Supervisor.start_link(__MODULE__, init_arg, name: __MODULE__)
-        end
-
-        def start_child(foo, bar, baz) do
-          # This will start child by calling MyWorker.start_link(init_arg, foo, bar, baz)
-          Supervisor.start_child(__MODULE__, [foo, bar, baz])
-        end
-
-        @impl true
-        def init(init_arg) do
-          children = [
-            # Or the deprecated: worker(MyWorker, [init_arg])
-            %{id: MyWorker, start: {MyWorker, :start_link, [init_arg]}}
-          ]
-
-          Supervisor.init(children, strategy: :simple_one_for_one)
-        end
-      end
-
-  It can be upgraded to the DynamicSupervisor like this:
-
-      defmodule MySupervisor do
-        use DynamicSupervisor
-
-        def start_link(init_arg) do
-          DynamicSupervisor.start_link(__MODULE__, init_arg, name: __MODULE__)
-        end
-
-        def start_child(foo, bar, baz) do
-          # If MyWorker is not using the new child specs, we need to pass a map:
-          # spec = %{id: MyWorker, start: {MyWorker, :start_link, [foo, bar, baz]}}
-          spec = {MyWorker, foo: foo, bar: bar, baz: baz}
-          DynamicSupervisor.start_child(__MODULE__, spec)
-        end
-
-        @impl true
-        def init(init_arg) do
-          DynamicSupervisor.init(
-            strategy: :one_for_one,
-            extra_arguments: [init_arg]
-          )
-        end
-      end
-
-  The difference is that the `DynamicSupervisor` expects the child specification
-  at the moment `start_child/2` is called, and no longer on the init callback.
-  If there are any initial arguments given on initialization, such as `[initial_arg]`,
-  it can be given in the `:extra_arguments` flag on `DynamicSupervisor.init/1`.
   """
 
   @behaviour GenServer
@@ -226,7 +169,15 @@ defmodule DynamicSupervisor do
   @typedoc "Supported strategies"
   @type strategy :: :one_for_one
 
-  @typedoc "Return values of `start_child` functions"
+  @typedoc """
+  Return values of `start_child` functions.
+
+  Unlike `Supervisor`, this module ignores the child spec ids,
+  so `{:error, {:already_started, pid}}` is not returned for child specs
+  given with the same id. `{:error, {:already_started, pid}}` is returned
+  however if a duplicate name is used when using
+  [name registration](`m:GenServer#module-name-registration`).
+  """
   @type on_start_child ::
           {:ok, pid}
           | {:ok, pid, info :: term}
@@ -396,11 +347,17 @@ defmodule DynamicSupervisor do
   @doc """
   Dynamically adds a child specification to `supervisor` and starts that child.
 
-  `child_spec` should be a valid child specification as detailed in the
-  "Child specification" section of the documentation for `Supervisor`. The child
-  process will be started as defined in the child specification. Note that while
+  `child_spec` should be a valid [child specification](`m:Supervisor#module-child-specification`).
+  The child process will be started as defined in the child specification. Note that while
   the `:id` field is still required in the spec, the value is ignored and
-  therefore does not need to be unique.
+  therefore does not need to be unique. Unlike `Supervisor`, this module does not
+  return `{:error, {:already_started, pid}}` for child specs given with the same id.
+  `{:error, {:already_started, pid}}` is returned however if a duplicate name is
+  used when using [name registration](`m:GenServer#module-name-registration`).
+
+  This function will block the `DynamicSupervisor` until the child initializes.
+  When starting too many processes dynamically, you may want to use a
+  `PartitionSupervisor` to split the work across multiple processes.
 
   If the child process start function returns `{:ok, child}` or `{:ok, child,
   info}`, then child specification and PID are added to the supervisor and
@@ -505,6 +462,14 @@ defmodule DynamicSupervisor do
   @doc """
   Terminates the given child identified by `pid`.
 
+  This function will block the `DynamicSupervisor` until the child
+  terminates, which may take an arbitrary amount of time if the child
+  is trapping exits and implements its own terminate callback.
+  For this reason, it is often better to ask the child process
+  itself to terminate, often by declaring in its child spec it has
+  a restart strategy of `:transient` (or `:temporary`) and then
+  sending it a message to stop with reason `:shutdown`.
+
   If successful, this function returns `:ok`. If there is no process with
   the given PID, this function returns `{:error, :not_found}`.
   """

lib/elixir/lib/enum.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defprotocol Enumerable do
   @moduledoc """
   Enumerable protocol used by `Enum` and `Stream` modules.
@@ -756,25 +760,9 @@ defmodule Enum do
   @doc since: "1.12.0"
   @spec count_until(t, pos_integer) :: non_neg_integer
   def count_until(enumerable, limit) when is_integer(limit) and limit > 0 do
-    stop_at = limit - 1
-
-    case Enumerable.count(enumerable) do
-      {:ok, value} ->
-        Kernel.min(value, limit)
-
-      {:error, module} ->
-        enumerable
-        |> module.reduce(
-          {:cont, 0},
-          fn
-            _, ^stop_at ->
-              {:halt, limit}
-
-            _, acc ->
-              {:cont, acc + 1}
-          end
-        )
-        |> elem(1)
+    case enumerable do
+      list when is_list(list) -> count_until_list(list, limit, 0)
+      _ -> count_until_enum(enumerable, limit)
     end
   end
 
@@ -793,24 +781,10 @@ defmodule Enum do
   @doc since: "1.12.0"
   @spec count_until(t, (element -> as_boolean(term)), pos_integer) :: non_neg_integer
   def count_until(enumerable, fun, limit) when is_integer(limit) and limit > 0 do
-    stop_at = limit - 1
-
-    Enumerable.reduce(enumerable, {:cont, 0}, fn
-      entry, ^stop_at ->
-        if fun.(entry) do
-          {:halt, limit}
-        else
-          {:cont, stop_at}
-        end
-
-      entry, acc ->
-        if fun.(entry) do
-          {:cont, acc + 1}
-        else
-          {:cont, acc}
-        end
-    end)
-    |> elem(1)
+    case enumerable do
+      list when is_list(list) -> count_until_list(list, fun, limit, 0)
+      _ -> count_until_enum(enumerable, fun, limit)
+    end
   end
 
   @doc """
@@ -1074,14 +1048,14 @@ defmodule Enum do
       6
 
       iex> Enum.fetch!([2, 4, 6], 4)
-      ** (Enum.OutOfBoundsError) out of bounds error
+      ** (Enum.OutOfBoundsError) out of bounds error at position 4 when traversing enumerable [2, 4, 6]
 
   """
   @spec fetch!(t, index) :: element
   def fetch!(enumerable, index) when is_integer(index) do
     case slice_forward(enumerable, index, 1, 1) do
       [value] -> value
-      [] -> raise Enum.OutOfBoundsError
+      [] -> raise Enum.OutOfBoundsError, index: index, enumerable: enumerable
     end
   end
 
@@ -2430,7 +2404,7 @@ defmodule Enum do
         {:ok, count, fun} when is_function(fun, 3) ->
           fun.(random_count(count), 1, 1)
 
-        # TODO: Remove deprecation on Elixir v1.20.
+        # TODO: Remove me on v2.0
         {:ok, count, fun} when is_function(fun, 2) ->
           IO.warn(
             "#{inspect(Enumerable.impl_for(enumerable))} must return a three arity function on slice/1"
@@ -2860,14 +2834,19 @@ defmodule Enum do
   end
 
   @doc """
-  Applies the given function to each element in the `enumerable`,
-  storing the result in a list and passing it as the accumulator
-  for the next computation. Uses the first element in the `enumerable`
-  as the starting value.
+  Passes each element from `enumerable` to the `fun` as the first argument,
+  stores the `fun` result in a list and passes the result as the second argument
+  for the next computation.
+
+  The `fun` isn't applied for the first element of the `enumerable`,
+  the element is taken as it is.
 
   ## Examples
 
-      iex> Enum.scan(1..5, &(&1 + &2))
+      iex> Enum.scan(["a", "b", "c", "d", "e"], fn element, acc -> element <> String.first(acc) end)
+      ["a", "ba", "cb", "dc", "ed"]
+
+      iex> Enum.scan(1..5, fn element, acc -> element + acc end)
       [1, 3, 6, 10, 15]
 
   """
@@ -2887,13 +2866,18 @@ defmodule Enum do
   end
 
   @doc """
-  Applies the given function to each element in the `enumerable`,
-  storing the result in a list and passing it as the accumulator
-  for the next computation. Uses the given `acc` as the starting value.
+  Passes each element from `enumerable` to the `fun` as the first argument,
+  stores the `fun` result in a list and passes the result as the second argument
+  for the next computation.
+
+  Passes the given `acc` as the second argument for the `fun` with the first element.
 
   ## Examples
 
-      iex> Enum.scan(1..5, 0, &(&1 + &2))
+      iex> Enum.scan(["a", "b", "c", "d", "e"], "_", fn element, acc -> element <> String.first(acc) end)
+      ["a_", "ba", "cb", "dc", "ed"]
+
+      iex> Enum.scan(1..5, 0, fn element, acc -> element + acc end)
       [1, 3, 6, 10, 15]
 
   """
@@ -3627,9 +3611,14 @@ defmodule Enum do
   end
 
   def take(enumerable, amount) when is_integer(amount) and amount < 0 do
-    {count, fun} = slice_count_and_fun(enumerable, 1)
-    first = Kernel.max(amount + count, 0)
-    fun.(first, count - first, 1)
+    case slice_count_and_fun(enumerable, 1) do
+      {0, _fun} ->
+        []
+
+      {count, fun} ->
+        first = Kernel.max(amount + count, 0)
+        fun.(first, count - first, 1)
+    end
   end
 
   @doc """
@@ -3906,6 +3895,7 @@ defmodule Enum do
 
   """
   @spec unzip(t) :: {[element], [element]}
+  def unzip(enumerable)
 
   def unzip([_ | _] = list) do
     :lists.reverse(list) |> unzip([], [])
@@ -3939,8 +3929,9 @@ defmodule Enum do
   If an integer offset is given as `fun_or_offset`, it will index from the given
   offset instead of from zero.
 
-  If a function is given as `fun_or_offset`, it will index by invoking the function
-  for each element and index (zero-based) of the enumerable.
+  If a 2-arity function is given as `fun_or_offset`, the function will be invoked
+  for each element in `enumerable` as the first argument and with a zero-based
+  index as the second. `with_index/2` returns a list with the result of each invocation.
 
   ## Examples
 
@@ -4051,10 +4042,10 @@ defmodule Enum do
   key in the left map and the matching key in the right map, but there is no such
   guarantee because map keys are not ordered! Consider the following:
 
-      left =  %{:a => 1, 1 => 3}
+      left = %{:a => 1, 1 => 3}
       right = %{:a => 1, :b => :c}
       Enum.zip(left, right)
-      # [{{1, 3}, {:a, 1}}, {{:a, 1}, {:b, :c}}]
+      #=> [{{1, 3}, {:a, 1}}, {{:a, 1}, {:b, :c}}]
 
   As you can see `:a` does not get paired with `:a`. If this is what you want,
   you should use `Map.merge/3`.
@@ -4127,8 +4118,11 @@ defmodule Enum do
       iex> Enum.zip_reduce([1, 2], [3, 4], 0, fn x, y, acc -> x + y + acc end)
       10
 
-      iex> Enum.zip_reduce([1, 2], [3, 4], [], fn x, y, acc -> [x + y | acc] end)
-      [6, 4]
+  If one of the lists has more entries than the others,
+  those entries are discarded:
+
+      iex> Enum.zip_reduce([1, 2, 3], [4, 5], [], fn x, y, acc -> [x + y | acc] end)
+      [7, 5]
   """
   @doc since: "1.12.0"
   @spec zip_reduce(t, t, acc, (enum1_elem :: term, enum2_elem :: term, acc -> acc)) :: acc
@@ -4164,7 +4158,10 @@ defmodule Enum do
       ...> end)
       [{1, 2, 3}, {1, 2, 3}]
 
-      iex> enums = [[1, 2], [a: 3, b: 4], [5, 6]]
+  If one of the lists has more entries than the others,
+  those entries are discarded:
+
+      iex> enums = [[1, 2], [a: 3, b: 4], [5, 6, 7]]
       ...> Enum.zip_reduce(enums, [], fn elements, acc ->
       ...>   [List.to_tuple(elements) | acc]
       ...> end)
@@ -4174,8 +4171,8 @@ defmodule Enum do
   @spec zip_reduce(t, acc, ([term], acc -> acc)) :: acc when acc: term
   def zip_reduce([], acc, reducer) when is_function(reducer, 2), do: acc
 
-  def zip_reduce(enums, acc, reducer) when is_function(reducer, 2) do
-    R.zip_with(enums, & &1).({:cont, acc}, &{:cont, reducer.(&1, &2)}) |> elem(1)
+  def zip_reduce(enumerables, acc, reducer) when is_function(reducer, 2) do
+    R.zip_with(enumerables, & &1).({:cont, acc}, &{:cont, reducer.(&1, &2)}) |> elem(1)
   end
 
   ## Helpers
@@ -4348,6 +4345,64 @@ defmodule Enum do
     enum |> reduce([], &reduce(&1, &2, fun)) |> :lists.reverse()
   end
 
+  # count_until
+
+  @compile {:inline, count_until_list: 3}
+
+  defp count_until_list([], _limit, acc), do: acc
+
+  defp count_until_list([_head | tail], limit, acc) do
+    case acc + 1 do
+      ^limit -> limit
+      acc -> count_until_list(tail, limit, acc)
+    end
+  end
+
+  defp count_until_enum(enumerable, limit) do
+    case Enumerable.count(enumerable) do
+      {:ok, value} ->
+        Kernel.min(value, limit)
+
+      {:error, module} ->
+        module.reduce(enumerable, {:cont, 0}, fn _entry, acc ->
+          case acc + 1 do
+            ^limit -> {:halt, limit}
+            acc -> {:cont, acc}
+          end
+        end)
+        |> elem(1)
+    end
+  end
+
+  @compile {:inline, count_until_list: 4}
+
+  defp count_until_list([], _fun, _limit, acc), do: acc
+
+  defp count_until_list([head | tail], fun, limit, acc) do
+    if fun.(head) do
+      case acc + 1 do
+        ^limit -> limit
+        acc -> count_until_list(tail, fun, limit, acc)
+      end
+    else
+      count_until_list(tail, fun, limit, acc)
+    end
+  end
+
+  defp count_until_enum(enumerable, fun, limit) do
+    Enumerable.reduce(enumerable, {:cont, 0}, fn entry, acc ->
+      if fun.(entry) do
+        case acc + 1 do
+          ^limit -> {:halt, limit}
+          acc -> {:cont, acc}
+        end
+      else
+        {:cont, acc}
+      end
+    end)
+    |> elem(1)
+  end
+
   # dedup
 
   defp dedup_list([value | tail], acc) do
@@ -4588,7 +4643,7 @@ defmodule Enum do
         amount = Kernel.min(amount, count - start) |> amount_with_step(step)
         fun.(start, amount, step)
 
-      # TODO: Remove me on v2.0.
+      # TODO: Remove me on v2.0
       {:ok, count, fun} when is_function(fun, 2) ->
         IO.warn(
           "#{inspect(Enumerable.impl_for(enumerable))} must return a three arity function on slice/1"
@@ -5005,3 +5060,72 @@ defimpl Enumerable, for: Function do
       description: "only anonymous functions of arity 2 are enumerable"
   end
 end
+
+defimpl Enumerable, for: Range do
+  def reduce(first..last//step, acc, fun) do
+    reduce(first, last, acc, fun, step)
+  end
+
+  # TODO: Remove me on v2.0
+  def reduce(%{__struct__: Range, first: first, last: last} = range, acc, fun) do
+    step = if first <= last, do: 1, else: -1
+    reduce(Map.put(range, :step, step), acc, fun)
+  end
+
+  defp reduce(_first, _last, {:halt, acc}, _fun, _step) do
+    {:halted, acc}
+  end
+
+  defp reduce(first, last, {:suspend, acc}, fun, step) do
+    {:suspended, acc, &reduce(first, last, &1, fun, step)}
+  end
+
+  defp reduce(first, last, {:cont, acc}, fun, step)
+       when step > 0 and first <= last
+       when step < 0 and first >= last do
+    reduce(first + step, last, fun.(first, acc), fun, step)
+  end
+
+  defp reduce(_, _, {:cont, acc}, _fun, _up) do
+    {:done, acc}
+  end
+
+  def member?(first..last//step, value) when is_integer(value) do
+    if step > 0 do
+      {:ok, first <= value and value <= last and rem(value - first, step) == 0}
+    else
+      {:ok, last <= value and value <= first and rem(value - first, step) == 0}
+    end
+  end
+
+  # TODO: Remove me on v2.0
+  def member?(%{__struct__: Range, first: first, last: last} = range, value)
+      when is_integer(value) do
+    step = if first <= last, do: 1, else: -1
+    member?(Map.put(range, :step, step), value)
+  end
+
+  def member?(_, _value) do
+    {:ok, false}
+  end
+
+  def count(range) do
+    {:ok, Range.size(range)}
+  end
+
+  def slice(first.._//step = range) do
+    {:ok, Range.size(range), &slice(first + &1 * step, step + &3 - 1, &2)}
+  end
+
+  # TODO: Remove me on v2.0
+  def slice(%{__struct__: Range, first: first, last: last} = range) do
+    step = if first <= last, do: 1, else: -1
+    slice(Map.put(range, :step, step))
+  end
+
+  defp slice(current, _step, 1), do: [current]
+
+  defp slice(current, step, remaining) when remaining > 1 do
+    [current | slice(current + step, step, remaining - 1)]
+  end
+end

lib/elixir/lib/exception.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Exception do
   @moduledoc """
   Functions for dealing with throw/catch/exit and exceptions.
@@ -78,6 +82,11 @@ defmodule Exception do
 
   @doc """
   Gets the message for an `exception`.
+
+  This function will invoke the `c:message/1` callback on the exception
+  module to retrieve the message. If the callback raises an exception or
+  returns a non-binary value, this function will rescue the error and
+  return a descriptive error message instead.
   """
   @spec message(t) :: String.t()
   def message(%module{__exception__: true} = exception) do
@@ -149,7 +158,7 @@ defmodule Exception do
   end
 
   @doc """
-  Normalizes and formats throw/errors/exits and stacktraces.
+  Normalizes and formats throws/errors/exits and stacktraces.
 
   It relies on `format_banner/3` and `format_stacktrace/1`
   to generate the final format.
@@ -173,15 +182,33 @@ defmodule Exception do
     end
   end
 
+  @doc false
+  def __format_message_with_term__(message, term) do
+    inspected =
+      term
+      |> inspect(pretty: true)
+      |> String.split("\n")
+      |> Enum.map_intersperse("\n", fn
+        "" -> ""
+        line -> "    " <> line
+      end)
+
+    IO.iodata_to_binary([message, "\n\n", inspected, "\n"])
+  end
+
   @doc """
-  Attaches information to exceptions for extra debugging.
+  Attaches information to throws/errors/exits for extra debugging.
 
   This operation is potentially expensive, as it reads data
   from the file system, parses beam files, evaluates code and
   so on.
 
-  If the exception module implements the optional `c:blame/2`
-  callback, it will be invoked to perform the computation.
+  If `kind` argument is `:error` and the `error` is an Erlang exception, this function will
+  normalize it. If the `error` argument is an Elixir exception, this function will invoke
+  the optional `c:blame/2` callback on the exception module if it is implemented.
+  Unlike `message/1`, this function will not rescue errors - if the callback raises an exception,
+  the error will propagate to the caller. It is your choice if you want to rescue and return
+  the original exception, return a different exception, or let it cascade.
   """
   @doc since: "1.5.0"
   @spec blame(:error, any, stacktrace) :: {t, stacktrace}
@@ -1040,7 +1067,12 @@ defmodule ArgumentError do
   An exception raised when an argument to a function is invalid.
 
   You can raise this exception when you want to signal that an argument to
-  a function is invalid.
+  a function is invalid. For example, this exception is raised when calling
+  `Integer.to_string/1` with an invalid argument:
+
+      iex> Integer.to_string(1.0)
+      ** (ArgumentError) errors were found at the given arguments:
+      ...
 
   `ArgumentError` exceptions have a single field, `:message` (a `t:String.t/0`),
   which is public and can be accessed freely when reading or creating `ArgumentError`
@@ -1057,8 +1089,7 @@ defmodule ArithmeticError do
   For example, this exception is raised if you divide by `0`:
 
       iex> 1 / 0
-      ** (ArithmeticError) bad argument in arithmetic expression: 1 / 0
-
+      ** (ArithmeticError) bad argument in arithmetic expression
   """
 
   defexception message: "bad argument in arithmetic expression"
@@ -1104,7 +1135,10 @@ defmodule SystemLimitError do
   @moduledoc """
   An exception raised when a system limit has been reached.
 
-  For example, this can happen if you try to create an atom that is too large.
+  For example, this can happen if you try to create an atom that is too large:
+
+      iex> String.to_atom(String.duplicate("a", 100_000))
+      ** (SystemLimitError) a system limit has been reached
   """
 
   defexception message: "a system limit has been reached"
@@ -1116,8 +1150,9 @@ defmodule MismatchedDelimiterError do
 
   For example:
 
-    * `[1, 2, 3}`
-    * `fn a -> )`
+      iex> Code.eval_string("[1, 2, 3}")
+      ** (MismatchedDelimiterError) mismatched delimiter found on nofile:1:9:
+      ...
 
   The following fields of this exceptions are public and can be accessed freely:
 
@@ -1131,7 +1166,6 @@ defmodule MismatchedDelimiterError do
     * `:closing_delimiter` - an atom representing the mismatched closing delimiter
     * `:expected_delimiter` - an atom representing the closing delimiter
     * `:description` - a description of the mismatched delimiter error
-
   """
 
   defexception [
@@ -1190,6 +1224,12 @@ defmodule SyntaxError do
   @moduledoc """
   An exception raised when there's a syntax error when parsing code.
 
+  For example:
+
+      iex> Code.eval_string("5 + 5h")
+      ** (SyntaxError) invalid syntax found on nofile:1:5:
+      ...
+
   The following fields of this exceptions are public and can be accessed freely:
 
     * `:file` (`t:Path.t/0` or `nil`) - the file where the error occurred, or `nil` if
@@ -1197,7 +1237,6 @@ defmodule SyntaxError do
     * `:line` - the line where the error occurred
     * `:column` - the column where the error occurred
     * `:description` - a description of the syntax error
-
   """
 
   defexception [:file, :line, :column, :snippet, description: "syntax error"]
@@ -1241,6 +1280,12 @@ defmodule TokenMissingError do
   @moduledoc """
   An exception raised when a token is missing when parsing code.
 
+  For example:
+
+      iex> Code.eval_string("[1, 2, 3")
+      ** (TokenMissingError) token missing on nofile:1:9:
+      ...
+
   The following fields of this exceptions are public and can be accessed freely:
 
     * `:file` (`t:Path.t/0` or `nil`) - the file where the error occurred, or `nil` if
@@ -1252,6 +1297,8 @@ defmodule TokenMissingError do
     * `:opening_delimiter` - an atom representing the opening delimiter
     * `:expected_delimiter` - an atom representing the expected delimiter
     * `:description` - a description of the missing token error
+
+  This is mostly raised by Elixir tooling when compiling and evaluating code.
   """
 
   defexception [
@@ -1331,12 +1378,18 @@ defmodule CompileError do
   @moduledoc """
   An exception raised when there's an error when compiling code.
 
+  For example:
+
+      1 = y
+      ** (CompileError) iex:1: undefined variable "y"
+
   The following fields of this exceptions are public and can be accessed freely:
 
     * `:file` (`t:Path.t/0` or `nil`) - the file where the error occurred, or `nil` if
       the error occurred in code that did not come from a file
     * `:line` (`t:non_neg_integer/0`) - the line where the error occurred
 
+  This is mostly raised by Elixir tooling when compiling and evaluating code.
   """
 
   defexception [:file, :line, description: "compile error"]
@@ -1354,12 +1407,19 @@ defmodule Kernel.TypespecError do
   @moduledoc """
   An exception raised when there's an error in a typespec.
 
+  For example, if your typespec definition points to an invalid type, you get an exception:
+
+      @type my_type :: intger()
+
+  will raise:
+
+      ** (Kernel.TypespecError) type intger/0 undefined
+
   The following fields of this exceptions are public and can be accessed freely:
 
     * `:file` (`t:Path.t/0` or `nil`) - the file where the error occurred, or `nil` if
       the error occurred in code that did not come from a file
     * `:line` (`t:non_neg_integer/0`) - the line where the error occurred
-
   """
 
   defexception [:file, :line, :description]
@@ -1374,6 +1434,16 @@ defmodule Kernel.TypespecError do
 end
 
 defmodule BadFunctionError do
+  @moduledoc """
+  An exception raised when a function is expected, but something else was given.
+
+  For example:
+
+      iex> value = "hello"
+      iex> value.()
+      ** (BadFunctionError) expected a function, got: "hello"
+  """
+
   defexception [:term]
 
   @impl true
@@ -1387,37 +1457,61 @@ defmodule BadFunctionError do
 end
 
 defmodule BadStructError do
+  @moduledoc deprecated:
+               "This exception is deprecated alongside the struct update syntax that raises it"
   defexception [:struct, :term]
 
   @impl true
   def message(exception) do
-    "expected a struct named #{inspect(exception.struct)}, got: #{inspect(exception.term)}"
+    Exception.__format_message_with_term__(
+      "expected a struct named #{inspect(exception.struct)}, got:",
+      exception.term
+    )
   end
 end
 
 defmodule BadMapError do
   @moduledoc """
-  An exception raised when something expected a map, but received something else.
+  An exception raised when a map is expected, but something else was given.
+
+  For example:
+
+      iex> value = "hello"
+      iex> %{value | key: "value"}
+      ** (BadMapError) expected a map, got:
+      ...
   """
 
   defexception [:term]
 
   @impl true
   def message(exception) do
-    "expected a map, got: #{inspect(exception.term)}"
+    Exception.__format_message_with_term__(
+      "expected a map, got:",
+      exception.term
+    )
   end
 end
 
 defmodule BadBooleanError do
   @moduledoc """
-  An exception raised when an operator expected a boolean, but received something else.
+  An exception raised when a boolean is expected, but something else was given.
+
+  This exception is raised by `and` and `or` when the first argument is not a boolean:
+
+      iex> 123 and true
+      ** (BadBooleanError) expected a boolean on left-side of "and", got:
+      ...
   """
 
   defexception [:term, :operator]
 
   @impl true
   def message(exception) do
-    "expected a boolean on left-side of \"#{exception.operator}\", got: #{inspect(exception.term)}"
+    Exception.__format_message_with_term__(
+      "expected a boolean on left-side of \"#{exception.operator}\", got:",
+      exception.term
+    )
   end
 end
 
@@ -1425,21 +1519,26 @@ defmodule MatchError do
   @moduledoc """
   An exception raised when a pattern match (`=/2`) fails.
 
+  For example:
+
+      iex> [_ | _] = []
+      ** (MatchError) no match of right hand side value:
+      ...
+
   The following fields of this exception are public and can be accessed freely:
 
     * `:term` (`t:term/0`) - the term that did not match the pattern
 
-  For example, this exception gets raised for code like this:
-
-      [_ | _] = []
-
   """
 
   defexception [:term]
 
   @impl true
   def message(exception) do
-    "no match of right hand side value: #{inspect(exception.term)}"
+    Exception.__format_message_with_term__(
+      "no match of right hand side value:",
+      exception.term
+    )
   end
 end
 
@@ -1448,24 +1547,28 @@ defmodule CaseClauseError do
   An exception raised when a term in a `case/2` expression
   does not match any of the defined `->` clauses.
 
+  For example:
+
+      iex> case System.unique_integer() do
+      ...>   bin when is_binary(bin) -> :oops
+      ...>   :ok -> :neither_this_one
+      ...> end
+      ** (CaseClauseError) no case clause matching:
+      ...
+
   The following fields of this exception are public and can be accessed freely:
 
     * `:term` (`t:term/0`) - the term that did not match any of the clauses
-
-  For example, this exception gets raised for a `case/2` like the following:
-
-      case System.unique_integer() do
-        bin when is_binary(bin) -> :oops
-        :ok -> :neither_this_one
-      end
-
   """
 
   defexception [:term]
 
   @impl true
   def message(exception) do
-    "no case clause matching: #{inspect(exception.term)}"
+    Exception.__format_message_with_term__(
+      "no case clause matching:",
+      exception.term
+    )
   end
 end
 
@@ -1474,28 +1577,32 @@ defmodule WithClauseError do
   An exception raised when a term in a `with/1` expression
   does not match any of the defined `->` clauses in its `else`.
 
-  The following fields of this exception are public and can be accessed freely:
-
-    * `:term` (`t:term/0`) - the term that did not match any of the clauses
-
   For example, this exception gets raised for a `with/1` like the following, because
   the `{:ok, 2}` term does not match the `:error` or `{:error, _}` clauses in the
   `else`:
 
-      with {:ok, 1} <- {:ok, 2} do
-        :woah
-      else
-        :error -> :error
-        {:error, _} -> :error
-      end
+      iex> with {:ok, 1} <- {:ok, 2} do
+      ...>   :woah
+      ...> else
+      ...>   :error -> :error
+      ...>   {:error, _} -> :error
+      ...> end
+      ** (WithClauseError) no with clause matching:
+      ...
 
+  The following fields of this exception are public and can be accessed freely:
+
+    * `:term` (`t:term/0`) - the term that did not match any of the clauses
   """
 
   defexception [:term]
 
   @impl true
   def message(exception) do
-    "no with clause matching: #{inspect(exception.term)}"
+    Exception.__format_message_with_term__(
+      "no with clause matching:",
+      exception.term
+    )
   end
 end
 
@@ -1505,11 +1612,11 @@ defmodule CondClauseError do
 
   For example, this exception gets raised for a `cond/1` like the following:
 
-      cond do
-        1 + 1 == 3 -> :woah
-        nil -> "yeah this won't happen
-      end
-
+      iex> cond do
+      ...>   1 + 1 == 3 -> :woah
+      ...>   nil -> "yeah this won't happen"
+      ...> end
+      ** (CondClauseError) no cond clause evaluated to a truthy value
   """
 
   defexception []
@@ -1522,8 +1629,20 @@ end
 
 defmodule TryClauseError do
   @moduledoc """
-  An exception raised when a term in a `try/1` expression
-  does not match any of the defined `->` clauses in its `else`.
+  An exception raised when none of the `else` clauses in a `try/1` match.
+
+  For example:
+
+      iex> try do
+      ...>   :ok
+      ...> rescue
+      ...>   e -> e
+      ...> else
+      ...>   # :ok -> :ok is missing
+      ...>   :not_ok -> :not_ok
+      ...> end
+      ** (TryClauseError) no try clause matching:
+      ...
 
   The following fields of this exception are public and can be accessed freely:
 
@@ -1534,13 +1653,22 @@ defmodule TryClauseError do
 
   @impl true
   def message(exception) do
-    "no try clause matching: #{inspect(exception.term)}"
+    Exception.__format_message_with_term__(
+      "no try clause matching:",
+      exception.term
+    )
   end
 end
 
 defmodule BadArityError do
   @moduledoc """
   An exception raised when a function is called with the wrong number of arguments.
+
+  For example:
+
+      my_function = fn x, y -> x + y end
+      my_function.(42)
+      ** (BadArityError) #Function<41.39164016/2 in :erl_eval.expr/6> with arity 2 called with 1 argument (42)
   """
 
   defexception [:function, :args]
@@ -1563,22 +1691,17 @@ defmodule UndefinedFunctionError do
   @moduledoc """
   An exception raised when a function is invoked that is not defined.
 
+  For example:
+
+      # Let's use apply/3 as otherwise Elixir emits a compile-time warning
+      iex> apply(String, :non_existing_fun, ["hello"])
+      ** (UndefinedFunctionError) function String.non_existing_fun/1 is undefined or private
+
   The following fields of this exception are public and can be accessed freely:
 
     * `:module` (`t:module/0`) - the module name
     * `:function` (`t:atom/0`) - the function name
     * `:arity` (`t:non_neg_integer/0`) - the arity of the function
-
-  For example, if you try to call `MyMod.non_existing_fun("hello", 1)`,
-  the error would look like:
-
-      %UndefinedFunctionError{
-        module: MyMod,
-        function: :non_existing_fun,
-        arity: 2,
-        # Other private fields...
-      }
-
   """
 
   @function_threshold 0.77
@@ -1788,7 +1911,7 @@ defmodule UndefinedFunctionError do
   end
 
   defp format_fa({_dist, fun, arity}) do
-    ["      * ", Macro.inspect_atom(:remote_call, fun), ?/, Integer.to_string(arity), ?\n]
+    ["    * ", Macro.inspect_atom(:remote_call, fun), ?/, Integer.to_string(arity), ?\n]
   end
 
   defp exports_for(module) do
@@ -1818,22 +1941,16 @@ defmodule FunctionClauseError do
   @moduledoc """
   An exception raised when a function call doesn't match any defined clause.
 
+  For example:
+
+      iex> URI.parse(:wrong_argument)
+      ** (FunctionClauseError) no function clause matching in URI.parse/1
+
   The following fields of this exception are public and can be accessed freely:
 
     * `:module` (`t:module/0`) - the module name
     * `:function` (`t:atom/0`) - the function name
     * `:arity` (`t:non_neg_integer/0`) - the arity of the function
-
-  For example, if you try to call a function such as `URI.parse/1` with something
-  other than a string, the error would look like:
-
-      %FunctionClauseError{
-        module: URI,
-        function: :parse,
-        arity: 1,
-        # Other private fields...
-      }
-
   """
 
   defexception [:module, :function, :arity, :kind, :args, :clauses]
@@ -1953,11 +2070,15 @@ defmodule Code.LoadError do
   @moduledoc """
   An exception raised when a file cannot be loaded.
 
+  This is typically raised by functions in the `Code` module, for example:
+
+      Code.require_file("missing_file.exs")
+      ** (Code.LoadError) could not load missing_file.exs. Reason: enoent
+
   The following fields of this exception are public and can be accessed freely:
 
     * `:file` (`t:String.t/0`) - the file name
     * `:reason` (`t:term/0`) - the reason why the file could not be loaded
-
   """
 
   defexception [:file, :message, :reason]
@@ -1974,23 +2095,16 @@ defmodule Protocol.UndefinedError do
   @moduledoc """
   An exception raised when a protocol is not implemented for a given value.
 
+  For example:
+
+      iex> Enum.at("A string!", 0)
+      ** (Protocol.UndefinedError) protocol Enumerable not implemented for BitString
+      ...
+
   The following fields of this exception are public and can be accessed freely:
 
     * `:protocol` (`t:module/0`) - the protocol that is not implemented
     * `:value` (`t:term/0`) - the value that does not implement the protocol
-
-  For example, this code:
-
-      Enum.at("A string!", 0)
-
-  would raise the following exception:
-
-      %Protocol.UndefinedError{
-        protocol: Enumerable,
-        value: "A string!",
-        # ...
-      }
-
   """
 
   defexception [:protocol, :value, description: ""]
@@ -2003,7 +2117,7 @@ defmodule Protocol.UndefinedError do
       # Indent only lines with contents on them
       |> String.replace(~r/^(?=.+)/m, "    ")
 
-    "protocol #{inspect(protocol)} not implemented for type " <>
+    "protocol #{inspect(protocol)} not implemented for " <>
       value_type(value) <>
       maybe_description(description) <>
       maybe_available(protocol) <>
@@ -2038,7 +2152,7 @@ defmodule Protocol.UndefinedError do
         ". There are no implementations for this protocol."
 
       {:consolidated, types} ->
-        ". This protocol is implemented for the following type(s): " <>
+        ". This protocol is implemented for: " <>
           Enum.map_join(types, ", ", &inspect/1)
 
       :not_consolidated ->
@@ -2052,13 +2166,17 @@ defmodule KeyError do
   An exception raised when a key is not found in a data structure.
 
   For example, this is raised by `Map.fetch!/2` when the given key
-  cannot be found in the given map.
+  cannot be found in the given map:
+
+      iex> map = %{name: "Alice", age: 25}
+      iex> Map.fetch!(map, :first_name)
+      ** (KeyError) key :first_name not found in:
+      ...
 
   The following fields of this exception are public and can be accessed freely:
 
     * `:term` (`t:term/0`) - the data structure that was searched
     * `:key` (`t:term/0`) - the key that was not found
-
   """
 
   defexception [:key, :term, :message]
@@ -2080,7 +2198,10 @@ defmodule KeyError do
           "make sure to add parentheses after the function name)"
 
       true ->
-        message <> " in: #{inspect(term, pretty: true, limit: :infinity)}"
+        Exception.__format_message_with_term__(
+          message <> " in:",
+          term
+        )
     end
   end
 
@@ -2122,7 +2243,7 @@ defmodule KeyError do
 
     case suggestions do
       [] -> []
-      suggestions -> [". Did you mean:\n\n" | format_suggestions(suggestions)]
+      suggestions -> ["\nDid you mean:\n\n" | format_suggestions(suggestions)]
     end
   end
 
@@ -2131,11 +2252,20 @@ defmodule KeyError do
     |> Enum.sort(&(elem(&1, 0) >= elem(&2, 0)))
     |> Enum.take(@max_suggestions)
     |> Enum.sort(&(elem(&1, 1) <= elem(&2, 1)))
-    |> Enum.map(fn {_, key} -> ["      * ", inspect(key), ?\n] end)
+    |> Enum.map(fn {_, key} -> ["    * ", inspect(key), ?\n] end)
   end
 end
 
 defmodule UnicodeConversionError do
+  @moduledoc """
+  An exception raised when converting data to or from Unicode.
+
+  For example:
+
+      iex> String.to_charlist(<<0xFF>>)
+      ** (UnicodeConversionError) invalid encoding starting at <<255>>
+
+  """
   defexception [:encoded, :message]
 
   def exception(opts) do
@@ -2213,10 +2343,31 @@ defmodule Enum.OutOfBoundsError do
   An exception that is raised when a function expects an enumerable to have
   a certain size but finds that it is too small.
 
-  For example, this is raised by `Access.at!/1`.
+  For example:
+
+      iex> Enum.fetch!([1, 2, 3], 5)
+      ** (Enum.OutOfBoundsError) out of bounds error at position 5 when traversing enumerable [1, 2, 3]
   """
 
-  defexception message: "out of bounds error"
+  defexception [:enumerable, :index, :message]
+
+  @impl true
+  def message(exception = %{message: nil}), do: message(exception.index, exception.enumerable)
+  def message(%{message: message}), do: message
+
+  def message(index, enumerable) do
+    "out of bounds error" <>
+      if index do
+        " at position #{index}"
+      else
+        ""
+      end <>
+      if enumerable do
+        " when traversing enumerable #{inspect(enumerable)}"
+      else
+        ""
+      end
+  end
 end
 
 defmodule Enum.EmptyError do
@@ -2224,7 +2375,11 @@ defmodule Enum.EmptyError do
   An exception that is raised when something expects a non-empty enumerable
   but finds an empty one.
 
-  For example, this is raised by `Enum.min/3`.
+  For example:
+
+      iex> Enum.min([])
+      ** (Enum.EmptyError) empty error
+
   """
 
   defexception message: "empty error"
@@ -2234,6 +2389,11 @@ defmodule File.Error do
   @moduledoc """
   An exception that is raised when a file operation fails.
 
+  For example, this exception is raised, when trying to read a non existent file:
+
+      iex> File.read!("nonexistent_file.txt")
+      ** (File.Error) could not read file "nonexistent_file.txt": no such file or directory
+
   The following fields of this exception are public and can be accessed freely:
 
     * `:path` (`t:Path.t/0`) - the path of the file that caused the error
@@ -2262,6 +2422,11 @@ defmodule File.CopyError do
   @moduledoc """
   An exception that is raised when copying a file fails.
 
+  For example, this exception is raised when trying to copy to file or directory that isn't present:
+
+      iex> File.cp_r!("non_existent", "source_dir/subdir")
+      ** (File.CopyError) could not copy recursively from "non_existent" to "source_dir/subdir". non_existent: no such file or directory
+
   The following fields of this exception are public and can be accessed freely:
 
     * `:source` (`t:Path.t/0`) - the source path
@@ -2291,6 +2456,11 @@ defmodule File.RenameError do
   @moduledoc """
   An exception that is raised when renaming a file fails.
 
+  For example, this exception is raised when trying to rename a file that isn't present:
+
+    iex> File.rename!("source.txt", "target.txt")
+    ** (File.RenameError) could not rename from "source.txt" to "target.txt": no such file or directory
+
   The following fields of this exception are public and can be accessed freely:
 
     * `:source` (`t:Path.t/0`) - the source path
@@ -2320,6 +2490,11 @@ defmodule File.LinkError do
   @moduledoc """
   An exception that is raised when linking a file fails.
 
+  For example, this exception is raised when trying to link to file that isn't present:
+
+      iex> File.ln!("existing.txt", "link.txt")
+      ** (File.LinkError) could not create hard link from "link.txt" to "existing.txt": no such file or directory
+
   The following fields of this exception are public and can be accessed freely:
 
     * `:existing` (`t:Path.t/0`) - the existing file to link
@@ -2334,12 +2509,25 @@ defmodule File.LinkError do
   def message(exception) do
     formatted = IO.iodata_to_binary(:file.format_error(exception.reason))
 
-    "could not #{exception.action} from #{inspect(exception.existing)} to " <>
-      "#{inspect(exception.new)}: #{formatted}"
+    "could not #{exception.action} from #{inspect(exception.new)} to " <>
+      "#{inspect(exception.existing)}: #{formatted}"
   end
 end
 
 defmodule ErlangError do
+  @moduledoc """
+  An exception raised when invoking an Erlang code that errors
+  with a value not handled by Elixir.
+
+  Most common error reasons, such as `:badarg` are automatically
+  converted into exceptions by Elixir. However, you may invoke some
+  code that emits a custom error reason and those get wrapped into
+  `ErlangError`:
+
+      iex> :erlang.error(:some_invalid_error)
+      ** (ErlangError) Erlang error: :some_invalid_error
+  """
+
   defexception [:original, :reason]
 
   @impl true
@@ -2362,7 +2550,7 @@ defmodule ErlangError do
             is_map(module) and is_atom(function) and is_map_key(module, function) ->
               "you attempted to apply a function named #{inspect(function)} on a map/struct. " <>
                 "If you are using Kernel.apply/3, make sure the module is an atom. " <>
-                if is_function(module[function]) do
+                if is_function(Map.get(module, function)) do
                   "If you are trying to invoke an anonymous function in a map/struct, " <>
                     "add a dot between the function name and the parenthesis: map.#{function}.()"
                 else
@@ -2547,61 +2735,3 @@ defmodule ErlangError do
   defp nth(3), do: "3rd"
   defp nth(n), do: "#{n}th"
 end
-
-defmodule Inspect.Error do
-  @moduledoc """
-  Raised when a struct cannot be inspected.
-  """
-  @enforce_keys [:exception_module, :exception_message, :stacktrace, :inspected_struct]
-  defexception @enforce_keys
-
-  @impl true
-  def exception(arguments) when is_list(arguments) do
-    exception = Keyword.fetch!(arguments, :exception)
-    exception_module = exception.__struct__
-    exception_message = Exception.message(exception) |> String.trim_trailing("\n")
-    stacktrace = Keyword.fetch!(arguments, :stacktrace)
-    inspected_struct = Keyword.fetch!(arguments, :inspected_struct)
-
-    %Inspect.Error{
-      exception_module: exception_module,
-      exception_message: exception_message,
-      stacktrace: stacktrace,
-      inspected_struct: inspected_struct
-    }
-  end
-
-  @impl true
-  def message(%__MODULE__{
-        exception_module: exception_module,
-        exception_message: exception_message,
-        inspected_struct: inspected_struct
-      }) do
-    ~s'''
-    got #{inspect(exception_module)} with message:
-
-        """
-    #{pad(exception_message, 4)}
-        """
-
-    while inspecting:
-
-    #{pad(inspected_struct, 4)}
-    '''
-  end
-
-  @doc false
-  def pad(message, padding_length)
-      when is_binary(message) and is_integer(padding_length) and padding_length >= 0 do
-    padding = String.duplicate(" ", padding_length)
-
-    message
-    |> String.split("\n")
-    |> Enum.map(fn
-      "" -> "\n"
-      line -> [padding, line, ?\n]
-    end)
-    |> IO.iodata_to_binary()
-    |> String.trim_trailing("\n")
-  end
-end

lib/elixir/lib/file.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule File do
   @moduledoc ~S"""
   This module contains functions to manipulate files.
@@ -262,8 +266,15 @@ defmodule File do
     * `:enotdir` - a component of `path` is not a directory;
       on some platforms, `:enoent` is returned instead
 
+  ## Examples
+
+      File.mkdir("test/unit")
+      #=> :ok
+
+      File.mkdir("non/existing")
+      #=> {:error, :enoent}
   """
-  @spec mkdir(Path.t()) :: :ok | {:error, posix}
+  @spec mkdir(Path.t()) :: :ok | {:error, posix | :badarg}
   def mkdir(path) do
     :file.make_dir(IO.chardata_to_string(path))
   end
@@ -271,6 +282,14 @@ defmodule File do
   @doc """
   Same as `mkdir/1`, but raises a `File.Error` exception in case of failure.
   Otherwise `:ok`.
+
+  ## Examples
+
+      File.mkdir!("test/unit")
+      #=> :ok
+
+      File.mkdir!("non/existing")
+      ** (File.Error) could not make directory "non/existing": no such file or directory
   """
   @spec mkdir!(Path.t()) :: :ok
   def mkdir!(path) do
@@ -298,9 +317,17 @@ defmodule File do
       directories of `path`
     * `:enospc`  - there is no space left on the device
     * `:enotdir` - a component of `path` is not a directory
+    * `:eperm`   - missed required permissions
 
+  ## Examples
+
+      File.mkdir_p("non/existing/parents")
+      #=> :ok
+
+      File.mkdir_p("/usr/sbin/temp")
+      #=> {:error, :eperm}
   """
-  @spec mkdir_p(Path.t()) :: :ok | {:error, posix}
+  @spec mkdir_p(Path.t()) :: :ok | {:error, posix | :badarg}
   def mkdir_p(path) do
     do_mkdir_p(IO.chardata_to_string(path))
   end
@@ -310,24 +337,23 @@ defmodule File do
   end
 
   defp do_mkdir_p(path) do
-    if dir?(path) do
+    parent = Path.dirname(path)
+
+    if parent == path do
       :ok
     else
-      parent = Path.dirname(path)
+      case do_mkdir_p(parent) do
+        :ok ->
+          case :file.make_dir(path) do
+            {:error, :eexist} ->
+              if dir?(path), do: :ok, else: {:error, :enotdir}
 
-      if parent == path do
-        # Protect against infinite loop
-        {:error, :einval}
-      else
-        _ = do_mkdir_p(parent)
+            other ->
+              other
+          end
 
-        case :file.make_dir(path) do
-          {:error, :eexist} = error ->
-            if dir?(path), do: :ok, else: error
-
-          other ->
-            other
-        end
+        e ->
+          e
       end
     end
   end
@@ -335,6 +361,14 @@ defmodule File do
   @doc """
   Same as `mkdir_p/1`, but raises a `File.Error` exception in case of failure.
   Otherwise `:ok`.
+
+  ## Examples
+
+      File.mkdir_p!("non/existing/parents")
+      #=> :ok
+
+      File.mkdir_p!("/usr/sbin/temp")
+      ** (File.Error) could not make directory (with -p) "/usr/sbin/temp": not owner
   """
   @spec mkdir_p!(Path.t()) :: :ok
   def mkdir_p!(path) do
@@ -365,8 +399,16 @@ defmodule File do
     * `:enomem`  - there is not enough memory for the contents of the file
 
   You can use `:file.format_error/1` to get a descriptive string of the error.
+
+  ## Examples
+
+      File.read("hello.txt")
+      #=> {:ok, "world"}
+
+      File.read("non_existing.txt")
+      #=> {:error, :enoent}
   """
-  @spec read(Path.t()) :: {:ok, binary} | {:error, posix}
+  @spec read(Path.t()) :: {:ok, binary} | {:error, posix | :badarg | :terminated | :system_limit}
   def read(path) do
     :file.read_file(IO.chardata_to_string(path))
   end
@@ -374,6 +416,14 @@ defmodule File do
   @doc """
   Returns a binary with the contents of the given filename,
   or raises a `File.Error` exception if an error occurs.
+
+  ## Examples
+
+      File.read!("hello.txt")
+      #=> "world"
+
+      File.read!("non_existing.txt")
+      ** (File.Error) could not read file "non_existing.txt": no such file or directory
   """
   @spec read!(Path.t()) :: binary
   def read!(path) do
@@ -407,8 +457,16 @@ defmodule File do
 
   Note: Since file times are stored in POSIX time format on most operating systems,
   it is faster to retrieve file information with the `time: :posix` option.
+
+  ## Examples
+
+      File.stat("hello.txt")
+      #=> {:ok, %File.Stat{...}}
+
+      File.stat("non_existing.txt", time: :posix)
+      #=> {:error, :enoent}
   """
-  @spec stat(Path.t(), stat_options) :: {:ok, File.Stat.t()} | {:error, posix}
+  @spec stat(Path.t(), stat_options) :: {:ok, File.Stat.t()} | {:error, posix | :badarg}
   def stat(path, opts \\ []) do
     opts = Keyword.put_new(opts, :time, :universal)
 
@@ -424,6 +482,14 @@ defmodule File do
   @doc """
   Same as `stat/2` but returns the `File.Stat` directly,
   or raises a `File.Error` exception if an error is returned.
+
+  ## Examples
+
+      File.stat!("hello.txt")
+      #=> %File.Stat{...}
+
+      File.stat!("non_existing.txt", time: :posix)
+      ** (File.Error) could not read file stats "non_existing.txt": no such file or directory
   """
   @spec stat!(Path.t(), stat_options) :: File.Stat.t()
   def stat!(path, opts \\ []) do
@@ -460,8 +526,16 @@ defmodule File do
 
   Note: Since file times are stored in POSIX time format on most operating systems,
   it is faster to retrieve file information with the `time: :posix` option.
+
+  ## Examples
+
+      File.lstat("link_to_hello")
+      #=> {:ok, %File.Stat{type: :symlink, ...}}
+
+      File.lstat("non_existing.txt", time: :posix)
+      #=> {:error, :enoent}
   """
-  @spec lstat(Path.t(), stat_options) :: {:ok, File.Stat.t()} | {:error, posix}
+  @spec lstat(Path.t(), stat_options) :: {:ok, File.Stat.t()} | {:error, posix | :badarg}
   def lstat(path, opts \\ []) do
     opts = Keyword.put_new(opts, :time, :universal)
 
@@ -477,6 +551,14 @@ defmodule File do
   @doc """
   Same as `lstat/2` but returns the `File.Stat` struct directly,
   or raises a `File.Error` exception if an error is returned.
+
+  ## Examples
+
+      File.lstat!("link_to_hello")
+      #=> %File.Stat{type: :symlink, ...}
+
+      File.lstat!("non_existing.txt", time: :posix)
+      ** (File.Error) could not read file stats "non_existing.txt": no such file or directory
   """
   @spec lstat!(Path.t(), stat_options) :: File.Stat.t()
   def lstat!(path, opts \\ []) do
@@ -506,9 +588,16 @@ defmodule File do
     * `:enoent` - path does not exist
     * `:enotsup` - symbolic links are not supported on the current platform
 
+  ## Examples
+
+      File.read_link("link_to_hello")
+      #=> {:ok, "hello.txt"}
+
+      File.read_link("hello.txt")
+      #=> {:error, :einval}
   """
   @doc since: "1.5.0"
-  @spec read_link(Path.t()) :: {:ok, binary} | {:error, posix}
+  @spec read_link(Path.t()) :: {:ok, binary} | {:error, posix | :badarg}
   def read_link(path) do
     case path |> IO.chardata_to_string() |> :file.read_link() do
       {:ok, target} -> {:ok, IO.chardata_to_string(target)}
@@ -519,6 +608,14 @@ defmodule File do
   @doc """
   Same as `read_link/1` but returns the target directly,
   or raises a `File.Error` exception if an error is returned.
+
+  ## Examples
+
+      File.read_link!("link_to_hello")
+      #=> "hello.txt"
+
+      File.read_link!("hello.txt")
+      ** (File.Error) could not read link "hello.txt": invalid argument
   """
   @doc since: "1.5.0"
   @spec read_link!(Path.t()) :: binary
@@ -535,8 +632,16 @@ defmodule File do
   @doc """
   Writes the given `File.Stat` back to the file system at the given
   path. Returns `:ok` or `{:error, reason}`.
+
+  ## Examples
+
+      File.write_stat("hello.txt", new_stat)
+      #=> :ok
+
+      File.write_stat("non_existing.txt", new_stat)
+      #=> {:error, :enoent}
   """
-  @spec write_stat(Path.t(), File.Stat.t(), stat_options) :: :ok | {:error, posix}
+  @spec write_stat(Path.t(), File.Stat.t(), stat_options) :: :ok | {:error, posix | :badarg}
   def write_stat(path, stat, opts \\ []) do
     opts = Keyword.put_new(opts, :time, :universal)
     :file.write_file_info(IO.chardata_to_string(path), File.Stat.to_record(stat), opts)
@@ -545,6 +650,14 @@ defmodule File do
   @doc """
   Same as `write_stat/3` but raises a `File.Error` exception if it fails.
   Returns `:ok` otherwise.
+
+  ## Examples
+
+      File.write_stat!("hello.txt", new_stat)
+      #=> :ok
+
+      File.write_stat!("non_existing.txt", new_stat)
+      ** (File.Error) could not write file stats "non_existing.txt": no such file or directory
   """
   @spec write_stat!(Path.t(), File.Stat.t(), stat_options) :: :ok
   def write_stat!(path, stat, opts \\ []) do
@@ -585,14 +698,15 @@ defmodule File do
       #=> :ok
 
   """
-  @spec touch(Path.t(), erlang_time() | posix_time()) :: :ok | {:error, posix}
+  @spec touch(Path.t(), erlang_time() | posix_time()) ::
+          :ok | {:error, posix | :badarg | :terminated | :system_limit}
   def touch(path, time \\ System.os_time(:second))
 
   def touch(path, time) when is_tuple(time) do
     path = IO.chardata_to_string(path)
 
     with {:error, :enoent} <- :elixir_utils.change_universal_time(path, time),
-         :ok <- write(path, "", [:append]),
+         :ok <- write(path, "", [:raw, :append]),
          do: :elixir_utils.change_universal_time(path, time)
   end
 
@@ -600,7 +714,7 @@ defmodule File do
     path = IO.chardata_to_string(path)
 
     with {:error, :enoent} <- :elixir_utils.change_posix_time(path, time),
-         :ok <- write(path, "", [:append]),
+         :ok <- write(path, "", [:raw, :append]),
          do: :elixir_utils.change_posix_time(path, time)
   end
 
@@ -639,9 +753,17 @@ defmodule File do
   Returns `:ok` if successful, `{:error, reason}` otherwise.
   If the operating system does not support hard links, returns
   `{:error, :enotsup}`.
+
+  ## Examples
+
+      File.ln("hello.txt", "hard_link_to_hello")
+      #=> :ok
+
+      File.ln("non_existing.txt", "link")
+      #=> {:error, :enoent}
   """
   @doc since: "1.5.0"
-  @spec ln(Path.t(), Path.t()) :: :ok | {:error, posix}
+  @spec ln(Path.t(), Path.t()) :: :ok | {:error, posix | :badarg}
   def ln(existing, new) do
     :file.make_link(IO.chardata_to_string(existing), IO.chardata_to_string(new))
   end
@@ -649,6 +771,14 @@ defmodule File do
   @doc """
   Same as `ln/2` but raises a `File.LinkError` exception if it fails.
   Returns `:ok` otherwise.
+
+  ## Examples
+
+      File.ln!("hello.txt", "hard_link_to_hello")
+      #=> :ok
+
+      File.ln!("non_existing.txt", "link")
+      ** (File.LinkError) could not create hard link from "non_existing.txt" to "link": no such file or directory
   """
   @doc since: "1.5.0"
   @spec ln!(Path.t(), Path.t()) :: :ok
@@ -672,9 +802,23 @@ defmodule File do
   Returns `:ok` if successful, `{:error, reason}` otherwise.
   If the operating system does not support symlinks, returns
   `{:error, :enotsup}`.
+
+  Creates a symlink even if the `existing` target actually doesn't exist
+
+  ## Examples
+
+      File.ln_s("hello.txt", "link_to_hello")
+      #=> :ok
+
+      File.ln_s("non_existing.txt", "link")
+      #=> :ok
+
+      # Returns error if `new` file exists
+      File.ln_s("non_existing.txt", "existed_link")
+      #=> {:error, :eexist}
   """
   @doc since: "1.5.0"
-  @spec ln_s(Path.t(), Path.t()) :: :ok | {:error, posix}
+  @spec ln_s(Path.t(), Path.t()) :: :ok | {:error, posix | :badarg}
   def ln_s(existing, new) do
     :file.make_symlink(IO.chardata_to_string(existing), IO.chardata_to_string(new))
   end
@@ -682,6 +826,15 @@ defmodule File do
   @doc """
   Same as `ln_s/2` but raises a `File.LinkError` exception if it fails.
   Returns `:ok` otherwise.
+
+  ## Examples
+
+      File.ln_s!("hello.txt", "link_to_hello")
+      #=> :ok
+
+      # Raises if `new` file exists
+      File.ln_s!("non_existing.txt", "existed_link")
+      ** (File.LinkError) could not create symlink from "non_existing.txt" to "existed_link": file already exists
   """
   @spec ln_s!(Path.t(), Path.t()) :: :ok
   def ln_s!(existing, new) do
@@ -719,9 +872,17 @@ defmodule File do
 
   Typical error reasons are the same as in `open/2`,
   `read/1` and `write/3`.
+
+  ## Examples
+
+      File.copy("hello.txt", "hello_copy.txt")
+      #=> {:ok, 6}
+
+      File.copy("non_existing.txt", "copy.txt")
+      #=> {:error, :enoent}
   """
   @spec copy(Path.t() | io_device, Path.t() | io_device, pos_integer | :infinity) ::
-          {:ok, non_neg_integer} | {:error, posix}
+          {:ok, non_neg_integer} | {:error, posix | :badarg | :terminated}
   def copy(source, destination, bytes_count \\ :infinity) do
     source = normalize_path_or_io_device(source)
     destination = normalize_path_or_io_device(destination)
@@ -732,6 +893,14 @@ defmodule File do
   @doc """
   The same as `copy/3` but raises a `File.CopyError` exception if it fails.
   Returns the `bytes_copied` otherwise.
+
+  ## Examples
+
+      File.copy!("hello.txt", "hello_copy.txt")
+      #=> 6
+
+      File.copy!("non_existing.txt", "copy.txt")
+      ** (File.CopyError) could not copy from "non_existing.txt" to "copy.txt": no such file or directory
   """
   @spec copy!(Path.t() | io_device, Path.t() | io_device, pos_integer | :infinity) ::
           non_neg_integer
@@ -765,13 +934,17 @@ defmodule File do
 
       # Rename file "a.txt" to "b.txt"
       File.rename("a.txt", "b.txt")
+      #=> :ok
 
       # Rename directory "samples" to "tmp"
       File.rename("samples", "tmp")
+      #=> :ok
 
+      File.rename("non_existing.txt", "existing.txt")
+      #=> {:error, :enoent}
   """
   @doc since: "1.1.0"
-  @spec rename(Path.t(), Path.t()) :: :ok | {:error, posix}
+  @spec rename(Path.t(), Path.t()) :: :ok | {:error, posix | :badarg}
   def rename(source, destination) do
     source = IO.chardata_to_string(source)
     destination = IO.chardata_to_string(destination)
@@ -781,6 +954,14 @@ defmodule File do
   @doc """
   The same as `rename/2` but raises a `File.RenameError` exception if it fails.
   Returns `:ok` otherwise.
+
+  ## Examples
+
+      File.rename!("samples", "tmp")
+      #=> :ok
+
+      File.rename!("non_existing.txt", "existing.txt")
+      ** (File.RenameError) could not rename from "non_existing.txt" to "existing.txt": no such file or directory
   """
   @doc since: "1.9.0"
   @spec rename!(Path.t(), Path.t()) :: :ok
@@ -798,7 +979,7 @@ defmodule File do
     end
   end
 
-  @doc """
+  @doc ~S"""
   Copies the contents of `source_file` to `destination_file` preserving its modes.
 
   `source_file` must be a file or a symbolic link to one. `destination_file` must
@@ -825,12 +1006,33 @@ defmodule File do
       The default callback returns `true`. On earlier versions, this callback could be
       given as third argument, but such behavior is now deprecated.
 
+  ## Examples
+
+      File.cp("hello.txt", "hello_copy.txt")
+      #=> :ok
+
+      File.cp("hello.txt", "hello_copy.txt", on_conflict: fn source, destination ->
+        IO.gets("Overwriting #{destination} by #{source}. Type y to confirm. ") == "y\n"
+      end)
+      #=> :ok
+
+      File.cp("non_existing.txt", "copy.txt")
+      #=> {:error, :enoent}
   """
-  @spec cp(Path.t(), Path.t(), on_conflict: on_conflict_callback) :: :ok | {:error, posix}
+  @spec cp(Path.t(), Path.t(), on_conflict: on_conflict_callback) ::
+          :ok | {:error, posix | :badarg | :terminated}
   def cp(source_file, destination_file, options \\ [])
 
   # TODO: Deprecate me on Elixir v1.19
   def cp(source_file, destination_file, callback) when is_function(callback, 2) do
+    IO.warn_once(
+      {__MODULE__, :cp},
+      fn ->
+        "passing a callback to File.cp/3 is deprecated, pass it as a on_conflict: callback option instead"
+      end,
+      3
+    )
+
     cp(source_file, destination_file, on_conflict: callback)
   end
 
@@ -851,9 +1053,22 @@ defmodule File do
     Path.expand(p1) !== Path.expand(p2)
   end
 
-  @doc """
+  @doc ~S"""
   The same as `cp/3`, but raises a `File.CopyError` exception if it fails.
   Returns `:ok` otherwise.
+
+  ## Examples
+
+      File.cp!("hello.txt", "hello_copy.txt")
+      #=> :ok
+
+      File.cp!("hello.txt", "hello_copy.txt", on_conflict: fn source, destination ->
+        IO.gets("Overwriting #{destination} by #{source}. Type y to confirm. ") == "y\n"
+      end)
+      #=> :ok
+
+      File.cp!("non_existing.txt", "copy.txt")
+      ** (File.CopyError) could not copy from "non_existing.txt" to "copy.txt": no such file or directory
   """
   @spec cp!(Path.t(), Path.t(), on_conflict: on_conflict_callback) :: :ok
   def cp!(source_file, destination_file, options \\ []) do
@@ -916,26 +1131,39 @@ defmodule File do
 
       # Copies file "a.txt" to "b.txt"
       File.cp_r("a.txt", "b.txt")
+      #=> {:ok, ["b.txt"]}
 
       # Copies all files in "samples" to "tmp"
       File.cp_r("samples", "tmp")
+      #=> {:ok, ["z.txt", "y.txt", "x.txt]}
 
       # Same as before, but asks the user how to proceed in case of conflicts
       File.cp_r("samples", "tmp", on_conflict: fn source, destination ->
         IO.gets("Overwriting #{destination} by #{source}. Type y to confirm. ") == "y\n"
       end)
+      #=> {:ok, ["z.txt", "y.txt", "x.txt]}
 
+      File.cp_r("non_existing.txt", "copy.txt")
+      #=> {:error, :enoent}
   """
   @spec cp_r(Path.t(), Path.t(),
           on_conflict: on_conflict_callback,
           dereference_symlinks: boolean()
         ) ::
-          {:ok, [binary]} | {:error, posix, binary}
+          {:ok, [binary]} | {:error, posix | :badarg | :terminated, binary}
 
   def cp_r(source, destination, options \\ [])
 
   # TODO: Deprecate me on Elixir v1.19
   def cp_r(source, destination, callback) when is_function(callback, 2) do
+    IO.warn_once(
+      {__MODULE__, :cp_r},
+      fn ->
+        "passing a callback to File.cp_r/3 is deprecated, pass it as a on_conflict: callback option instead"
+      end,
+      3
+    )
+
     cp_r(source, destination, on_conflict: callback)
   end
 
@@ -962,6 +1190,17 @@ defmodule File do
   @doc """
   The same as `cp_r/3`, but raises a `File.CopyError` exception if it fails.
   Returns the list of copied files otherwise.
+
+  ## Examples
+
+      File.cp_r!("a.txt", "b.txt")
+      #=> ["b.txt"]
+
+      File.cp_r!("samples", "tmp")
+      #=> ["z.txt", "y.txt", "x.txt]
+
+      File.cp_r!("non_existing.txt", "copy.txt")
+      ** (File.CopyError) could not copy recursively from "non_existing.txt" to "copy.txt". non_existing.txt: no such file or directory
   """
   @spec cp_r!(Path.t(), Path.t(),
           on_conflict: on_conflict_callback,
@@ -985,7 +1224,13 @@ defmodule File do
   defp do_cp_r(src, dest, on_conflict, dereference?, acc) when is_list(acc) do
     case :elixir_utils.read_link_type(src) do
       {:ok, :regular} ->
-        do_cp_file(src, dest, on_conflict, acc)
+        case do_cp_file(src, dest, on_conflict, acc) do
+          # we don't have a way to make a distinction between a non-existing src
+          # or dest being a non-existing dir in the case of :enoent,
+          # but we already know that src exists here.
+          {:error, :enoent, _} -> {:error, :enoent, dest}
+          other -> other
+        end
 
       {:ok, :symlink} ->
         case :file.read_link(src) do
@@ -1122,9 +1367,19 @@ defmodule File do
       the parent directories
     * `:eisdir`  - the named file is a directory
 
-  Check `File.open/2` for other available options.
+  Check `File.open/2` for the list of available `modes`.
+
+  ## Examples
+
+      File.write("hello.txt", "world!")
+      #=> :ok
+
+      File.write("temp", "world!")
+      #=> {:error, :eisdir}
+
   """
-  @spec write(Path.t(), iodata, [mode]) :: :ok | {:error, posix}
+  @spec write(Path.t(), iodata, [mode]) ::
+          :ok | {:error, posix | :badarg | :terminated | :system_limit}
   def write(path, content, modes \\ []) do
     modes = normalize_modes(modes, false)
     :file.write_file(IO.chardata_to_string(path), content, modes)
@@ -1133,6 +1388,14 @@ defmodule File do
   @doc """
   Same as `write/3` but raises a `File.Error` exception if it fails.
   Returns `:ok` otherwise.
+
+  ## Examples
+
+      File.write!("hello.txt", "world!")
+      #=> :ok
+
+      File.write!("temp", "world!")
+      ** (File.Error) could not write to file "temp": illegal operation on a directory
   """
   @spec write!(Path.t(), iodata, [mode]) :: :ok
   def write!(path, content, modes \\ []) do
@@ -1171,9 +1434,8 @@ defmodule File do
 
       File.rm("tmp_dir/")
       #=> {:error, :eperm}
-
   """
-  @spec rm(Path.t()) :: :ok | {:error, posix}
+  @spec rm(Path.t()) :: :ok | {:error, posix | :badarg}
   def rm(path) do
     path = IO.chardata_to_string(path)
 
@@ -1211,6 +1473,14 @@ defmodule File do
   @doc """
   Same as `rm/1`, but raises a `File.Error` exception in case of failure.
   Otherwise `:ok`.
+
+  ## Examples
+
+      File.rm!("file.txt")
+      #=> :ok
+
+      File.rm!("non_existing/")
+      ** (File.Error) could not remove file "non_existing/": no such file or directory
   """
   @spec rm!(Path.t()) :: :ok
   def rm!(path) do
@@ -1239,9 +1509,8 @@ defmodule File do
 
       File.rmdir("file.txt")
       #=> {:error, :enotdir}
-
   """
-  @spec rmdir(Path.t()) :: :ok | {:error, posix}
+  @spec rmdir(Path.t()) :: :ok | {:error, posix | :badarg}
   def rmdir(path) do
     :file.del_dir(IO.chardata_to_string(path))
   end
@@ -1249,8 +1518,19 @@ defmodule File do
   @doc """
   Same as `rmdir/1`, but raises a `File.Error` exception in case of failure.
   Otherwise `:ok`.
+
+  ## Examples
+
+      File.rmdir!("tmp_dir")
+      #=> :ok
+
+      File.rmdir!("non_empty_dir")
+      ** (File.Error) could not remove directory "non_empty_dir": directory is not empty
+
+      File.rmdir!("file.txt")
+      ** (File.Error) could not remove directory "file.txt": not a directory
   """
-  @spec rmdir!(Path.t()) :: :ok | {:error, posix}
+  @spec rmdir!(Path.t()) :: :ok
   def rmdir!(path) do
     case rmdir(path) do
       :ok ->
@@ -1281,8 +1561,10 @@ defmodule File do
       File.rm_rf("unknown")
       #=> {:ok, []}
 
+      File.rm_rf("/tmp")
+      #=> {:error, :eperm, "/tmp"}
   """
-  @spec rm_rf(Path.t()) :: {:ok, [binary]} | {:error, posix, binary}
+  @spec rm_rf(Path.t()) :: {:ok, [binary]} | {:error, posix | :badarg, binary}
   def rm_rf(path) do
     {major, _} = :os.type()
 
@@ -1376,7 +1658,18 @@ defmodule File do
 
   @doc """
   Same as `rm_rf/1` but raises a `File.Error` exception in case of failures,
-  otherwise the list of files or directories removed.
+  otherwise returns the list of files or directories removed.
+
+  ## Examples
+
+      File.rm_rf!("samples")
+      #=> ["samples", "samples/1.txt"]
+
+      File.rm_rf!("unknown")
+      #=> []
+
+      File.rm_rf!("/tmp")
+      ** (File.Error) could not remove files and directories recursively from "/tmp": not owner
   """
   @spec rm_rf!(Path.t()) :: [binary]
   def rm_rf!(path) do
@@ -1480,8 +1773,10 @@ defmodule File do
       File.close(file)
 
   """
-  @spec open(Path.t(), [mode | :ram]) :: {:ok, io_device | file_descriptor} | {:error, posix}
-  @spec open(Path.t(), (io_device | file_descriptor -> res)) :: {:ok, res} | {:error, posix}
+  @spec open(Path.t(), [mode | :ram]) ::
+          {:ok, io_device | file_descriptor} | {:error, posix | :badarg | :system_limit}
+  @spec open(Path.t(), (io_device | file_descriptor -> res)) ::
+          {:ok, res} | {:error, posix | :badarg | :system_limit}
         when res: var
   def open(path, modes_or_function \\ [])
 
@@ -1508,16 +1803,17 @@ defmodule File do
   is given. For this reason, we do not recommend passing
   `:delayed_write` to this function.
 
+  See `open/2` for the list of available `modes`.
+
   ## Examples
 
       File.open("file.txt", [:read, :write], fn file ->
         IO.read(file, :line)
       end)
-
-  See `open/2` for the list of available `modes`.
+      #=> {:ok, "file content"}
   """
   @spec open(Path.t(), [mode | :ram], (io_device | file_descriptor -> res)) ::
-          {:ok, res} | {:error, posix}
+          {:ok, res} | {:error, posix | :badarg | :system_limit}
         when res: var
   def open(path, modes, function) when is_list(modes) and is_function(function, 1) do
     case open(path, modes) do
@@ -1538,6 +1834,13 @@ defmodule File do
   could not be opened. Returns the IO device otherwise.
 
   See `open/2` for the list of available modes.
+
+  ## Examples
+
+      File.open!("file.txt", fn file ->
+        IO.read(file, :line)
+      end)
+      #=> "file content"
   """
   @spec open!(Path.t(), [mode | :ram]) :: io_device | file_descriptor
   @spec open!(Path.t(), (io_device | file_descriptor -> res)) :: res when res: var
@@ -1558,6 +1861,13 @@ defmodule File do
   If it succeeds opening the file, it returns the `function` result on the IO device.
 
   See `open/2` for the list of available `modes`.
+
+  ## Examples
+
+      File.open!("file.txt", [:read, :write], fn file ->
+        IO.read(file, :line)
+      end)
+      #=> "file content"
   """
   @spec open!(Path.t(), [mode | :ram], (io_device | file_descriptor -> res)) :: res when res: var
   def open!(path, modes, function) do
@@ -1577,8 +1887,17 @@ defmodule File do
   if read permissions do not exist for the parent directories of the
   current directory. For this reason, returns `{:ok, cwd}` in case
   of success, `{:error, reason}` otherwise.
+
+  ## Examples
+
+      File.cwd()
+      #=> {:ok, "/Users/user/elixir/elixir_lang"}
+
+      # Missing read permission for one of the parents of the current directory
+      File.cwd()
+      #=> {:error, :eacces}
   """
-  @spec cwd() :: {:ok, binary} | {:error, posix}
+  @spec cwd() :: {:ok, binary} | {:error, posix | :badarg}
   def cwd() do
     case :file.get_cwd() do
       {:ok, base} -> {:ok, IO.chardata_to_string(fix_drive_letter(base))}
@@ -1597,6 +1916,11 @@ defmodule File do
 
   @doc """
   The same as `cwd/0`, but raises a `File.Error` exception if it fails.
+
+  ## Examples
+
+      File.cwd!()
+      #=> "/Users/user/elixir/elixir_lang"
   """
   @spec cwd!() :: binary
   def cwd!() do
@@ -1619,14 +1943,30 @@ defmodule File do
   of `System.cmd/3` and `Port.open/2`.
 
   Returns `:ok` if successful, `{:error, reason}` otherwise.
+
+  ## Examples
+
+      File.cd("bin")
+      #=> :ok
+
+      File.cd("non_existing_dir")
+      #=> {:error, :enoent}
   """
-  @spec cd(Path.t()) :: :ok | {:error, posix}
+  @spec cd(Path.t()) :: :ok | {:error, posix | :badarg | :no_translation}
   def cd(path) do
     :file.set_cwd(IO.chardata_to_string(path))
   end
 
   @doc """
   The same as `cd/1`, but raises a `File.Error` exception if it fails.
+
+  ## Examples
+
+      File.cd!("bin")
+      #=> :ok
+
+      File.cd!("non_existing_dir")
+      ** (File.Error) could not set current working directory to "non_existing_dir": no such file or directory
   """
   @spec cd!(Path.t()) :: :ok
   def cd!(path) do
@@ -1655,6 +1995,14 @@ defmodule File do
 
   Raises an error if retrieving or changing the current
   directory fails.
+
+  ## Examples
+
+      File.cd!("bin", fn -> do_something() end)
+      #=> :result_of_do_something
+
+      File.cd!("non_existing_dir", fn -> do_something() end)
+      ** (File.Error) could not set current working directory to "non_existing_dir": no such file or directory
   """
   @spec cd!(Path.t(), (-> res)) :: res when res: var
   def cd!(path, function) do
@@ -1678,8 +2026,16 @@ defmodule File do
 
   Returns `{:ok, files}` in case of success,
   `{:error, reason}` otherwise.
+
+  ## Examples
+
+      File.ls("bin")
+      #=> {:ok, ["iex", "elixir"]}
+
+      File.ls("non_existing_dir")
+      #=> {:error, :enoent}
   """
-  @spec ls(Path.t()) :: {:ok, [binary]} | {:error, posix}
+  @spec ls(Path.t()) :: {:ok, [binary]} | {:error, posix | :badarg | {:no_translation, binary}}
   def ls(path \\ ".") do
     case :file.list_dir(IO.chardata_to_string(path)) do
       {:ok, file_list} -> {:ok, Enum.map(file_list, &IO.chardata_to_string/1)}
@@ -1689,6 +2045,14 @@ defmodule File do
 
   @doc """
   The same as `ls/1` but raises a `File.Error` exception in case of an error.
+
+  ## Examples
+
+      File.ls!("bin")
+      #=> ["iex", "elixir"]
+
+      File.ls!("non_existing_dir")
+      ** (File.Error) could not list directory "non_existing_dir": no such file or directory
   """
   @spec ls!(Path.t()) :: [binary]
   def ls!(path \\ ".") do
@@ -1711,6 +2075,15 @@ defmodule File do
   Note that if the option `:delayed_write` was used when opening the file,
   `close/1` might return an old write error and not even try to close the file.
   See `open/2` for more information.
+
+  ## Examples
+
+      {:ok, file} = File.open("hello.txt")
+      File.close(file)
+      #=> :ok
+
+      File.close(:not_an_io_device)
+      #=> {:error, :badarg}
   """
   @spec close(io_device) :: :ok | {:error, posix | :badarg | :terminated}
   def close(io_device) do
@@ -1776,15 +2149,17 @@ defmodule File do
   that is skipped whenever enumerating the stream (if both `:read_offset`
   and `:trim_bom` are given, the offset is skipped after the BOM).
 
+  See `Stream.run/1` for an example of streaming into a file.
+
   ## Examples
 
       # Read a utf8 text file which may include BOM
       File.stream!("./test/test.txt", [:trim_bom, encoding: :utf8])
+      #=> %File.Stream{path: "./test/test.txt", ...}
 
       # Read in 2048 byte chunks rather than lines
       File.stream!("./test/test.data", 2048)
-
-  See `Stream.run/1` for an example of streaming into a file.
+      #=> %File.Stream{path: "./test/test.data", ...}
   """
   @spec stream!(Path.t(), :line | pos_integer, [stream_mode]) :: File.Stream.t()
   def stream!(path, line_or_bytes, modes)
@@ -1824,8 +2199,16 @@ defmodule File do
   write, read and execute permission to the owner
   and both read and execute permission to group
   and others.
+
+  ## Examples
+
+      File.chmod("hello.txt", 0o755)
+      #=> :ok
+
+      File.chmod("non_existing.txt", 0o755)
+      #=> {:error, :enoent}
   """
-  @spec chmod(Path.t(), non_neg_integer) :: :ok | {:error, posix}
+  @spec chmod(Path.t(), non_neg_integer) :: :ok | {:error, posix | :badarg}
   def chmod(path, mode) do
     :file.change_mode(IO.chardata_to_string(path), mode)
   end
@@ -1833,6 +2216,14 @@ defmodule File do
   @doc """
   Same as `chmod/2`, but raises a `File.Error` exception in case of failure.
   Otherwise `:ok`.
+
+  ## Examples
+
+      File.chmod!("hello.txt", 0o755)
+      #=> :ok
+
+      File.chmod!("non_existing.txt", 0o755)
+      ** (File.Error) could not change mode for "non_existing.txt": no such file or directory
   """
   @spec chmod!(Path.t(), non_neg_integer) :: :ok
   def chmod!(path, mode) do
@@ -1852,8 +2243,16 @@ defmodule File do
   Changes the group given by the group ID `gid`
   for a given `file`. Returns `:ok` on success, or
   `{:error, reason}` on failure.
+
+  ## Examples
+
+      File.chgrp("hello.txt", 10)
+      #=> :ok
+
+      File.chgrp("non_existing.txt", 10)
+      #=> {:error, :enoent}
   """
-  @spec chgrp(Path.t(), non_neg_integer) :: :ok | {:error, posix}
+  @spec chgrp(Path.t(), non_neg_integer) :: :ok | {:error, posix | :badarg}
   def chgrp(path, gid) do
     :file.change_group(IO.chardata_to_string(path), gid)
   end
@@ -1861,6 +2260,14 @@ defmodule File do
   @doc """
   Same as `chgrp/2`, but raises a `File.Error` exception in case of failure.
   Otherwise `:ok`.
+
+  ## Examples
+
+    File.chgrp!("hello.txt", 10)
+    #=> :ok
+
+    File.chgrp!("non_existing.txt", 10)
+    ** (File.Error) could not change group for "non_existing.txt": no such file or directory
   """
   @spec chgrp!(Path.t(), non_neg_integer) :: :ok
   def chgrp!(path, gid) do
@@ -1880,8 +2287,16 @@ defmodule File do
   Changes the owner given by the user ID `uid`
   for a given `file`. Returns `:ok` on success,
   or `{:error, reason}` on failure.
+
+  ## Examples
+
+      File.chown("hello.txt", 15)
+      #=> :ok
+
+      File.chown("secret.txt", 15)
+      #=> {:error, :eperm}
   """
-  @spec chown(Path.t(), non_neg_integer) :: :ok | {:error, posix}
+  @spec chown(Path.t(), non_neg_integer) :: :ok | {:error, posix | :badarg}
   def chown(path, uid) do
     :file.change_owner(IO.chardata_to_string(path), uid)
   end
@@ -1889,6 +2304,14 @@ defmodule File do
   @doc """
   Same as `chown/2`, but raises a `File.Error` exception in case of failure.
   Otherwise `:ok`.
+
+  ## Examples
+
+      File.chown!("hello.txt", 15)
+      #=> :ok
+
+      File.chown!("secret.txt", 15)
+      ** (File.Error) could not change owner for "secret.txt": not owner
   """
   @spec chown!(Path.t(), non_neg_integer) :: :ok
   def chown!(path, uid) do

lib/elixir/lib/file/stat.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 require Record
 
 defmodule File.Stat do

lib/elixir/lib/file/stream.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule File.Stream do
   @moduledoc """
   Defines a `File.Stream` struct returned by `File.stream!/3`.

lib/elixir/lib/float.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 import Kernel, except: [round: 1]
 
 defmodule Float do
@@ -164,40 +168,50 @@ defmodule Float do
   end
 
   defp parse_unsigned(<<digit, rest::binary>>) when digit in ?0..?9,
-    do: parse_unsigned(rest, false, false, <<digit>>)
+    do: parse_unsigned(rest, false, false, [digit])
 
   defp parse_unsigned(binary) when is_binary(binary), do: :error
 
   defp parse_unsigned(<<digit, rest::binary>>, dot?, e?, acc) when digit in ?0..?9,
-    do: parse_unsigned(rest, dot?, e?, <<acc::binary, digit>>)
+    do: parse_unsigned(rest, dot?, e?, [digit | acc])
 
   defp parse_unsigned(<<?., digit, rest::binary>>, false, false, acc) when digit in ?0..?9,
-    do: parse_unsigned(rest, true, false, <<acc::binary, ?., digit>>)
+    do: parse_unsigned(rest, true, false, [digit, ?. | acc])
 
   defp parse_unsigned(<<exp_marker, digit, rest::binary>>, dot?, false, acc)
        when exp_marker in ~c"eE" and digit in ?0..?9,
-       do: parse_unsigned(rest, true, true, <<add_dot(acc, dot?)::binary, ?e, digit>>)
+       do: parse_unsigned(rest, true, true, [digit, ?e | add_dot(acc, dot?)])
 
   defp parse_unsigned(<<exp_marker, sign, digit, rest::binary>>, dot?, false, acc)
        when exp_marker in ~c"eE" and sign in ~c"-+" and digit in ?0..?9,
-       do: parse_unsigned(rest, true, true, <<add_dot(acc, dot?)::binary, ?e, sign, digit>>)
+       do: parse_unsigned(rest, true, true, [digit, sign, ?e | add_dot(acc, dot?)])
 
   # When floats are expressed in scientific notation, :erlang.binary_to_float/1 can raise an
   # ArgumentError if the e exponent is too big. For example, "1.0e400". Because of this, we
   # rescue the ArgumentError here and return an error.
   defp parse_unsigned(rest, dot?, true = _e?, acc) do
-    :erlang.binary_to_float(add_dot(acc, dot?))
+    acc
+    |> add_dot(dot?)
+    |> :lists.reverse()
+    |> :erlang.list_to_float()
   rescue
     ArgumentError -> :error
   else
     float -> {float, rest}
   end
 
-  defp parse_unsigned(rest, dot?, false = _e?, acc),
-    do: {:erlang.binary_to_float(add_dot(acc, dot?)), rest}
+  defp parse_unsigned(rest, dot?, false = _e?, acc) do
+    float =
+      acc
+      |> add_dot(dot?)
+      |> :lists.reverse()
+      |> :erlang.list_to_float()
+
+    {float, rest}
+  end
 
   defp add_dot(acc, true), do: acc
-  defp add_dot(acc, false), do: acc <> ".0"
+  defp add_dot(acc, false), do: [?0, ?. | acc]
 
   @doc """
   Rounds a float to the largest float less than or equal to `number`.

lib/elixir/lib/function.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Function do
   @moduledoc """
   A set of functions for working with functions.

lib/elixir/lib/gen_event.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule GenEvent do
   # Functions from this module are deprecated in elixir_dispatch.
 

lib/elixir/lib/gen_event/stream.ex

@@ -1,5 +1,10 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule GenEvent.Stream do
   @moduledoc false
+  @moduledoc deprecated: "This functionality is no longer supported"
   defstruct manager: nil, timeout: :infinity
 
   @type t :: %__MODULE__{manager: GenEvent.manager(), timeout: timeout}
@@ -46,6 +51,9 @@ defmodule GenEvent.Stream do
 end
 
 defimpl Enumerable, for: GenEvent.Stream do
+  @moduledoc false
+  @moduledoc deprecated: "This functionality is no longer supported"
+
   def reduce(stream, acc, fun) do
     start_fun = fn -> start(stream) end
     next_fun = &next(stream, &1)

lib/elixir/lib/gen_server.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule GenServer do
   @moduledoc """
   A behaviour module for implementing the server of a client-server relation.
@@ -203,14 +207,16 @@ defmodule GenServer do
   The generated `child_spec/1` can be customized with the following options:
 
     * `:id` - the child specification identifier, defaults to the current module
-    * `:restart` - when the child should be restarted, defaults to `:permanent`
-    * `:shutdown` - how to shut down the child, either immediately or by giving it time to shut down
+    * [`:restart`](`m:Supervisor#module-restart-values-restart`) - when the
+      child should be restarted, defaults to `:permanent`
+    * [`:shutdown`](`m:Supervisor#module-shutdown-values-shutdown`) - how to
+      shut down the child, either immediately or by giving it time to shut down
 
   For example:
 
       use GenServer, restart: :transient, shutdown: 10_000
 
-  See the "Child specification" section in the `Supervisor` module for more
+  See the ["Child specification"](`m:Supervisor#module-child_spec-1-function`) section in the `Supervisor` module for more
   detailed information. The `@doc` annotation immediately preceding
   `use GenServer` will be attached to the generated `child_spec/1` function.
 
@@ -265,6 +271,14 @@ defmodule GenServer do
   generated atoms won't be garbage-collected. For such cases, you can
   set up your own local registry by using the `Registry` module.
 
+  For example:
+
+      {:ok, _} = Registry.start_link(keys: :unique, name: :stacks)
+      name = {:via, Registry, {:stacks, "stack 1"}}
+      {:ok, _pid} = GenServer.start_link(Stack, "hello", name: name)
+      GenServer.whereis(name)
+      #=> #PID<0.150.0>
+
   ## Receiving "regular" messages
 
   The goal of a `GenServer` is to abstract the "receive" loop for developers,
@@ -1098,8 +1112,8 @@ defmodule GenServer do
   arrives or a timeout occurs. `c:handle_call/3` will be called on the server
   to handle the request.
 
-  `server` can be any of the values described in the "Name registration"
-  section of the documentation for this module.
+  `server` can be a PID or any of the other values described in the
+  "Name registration" section of the documentation for this module.
 
   ## Timeouts
 

lib/elixir/lib/hash_dict.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule HashDict do
   @moduledoc """
   Tuple-based HashDict implementation.
@@ -256,6 +260,9 @@ defmodule HashDict do
 end
 
 defimpl Enumerable, for: HashDict do
+  @moduledoc false
+  @moduledoc deprecated: "Use Map instead"
+
   def reduce(dict, acc, fun) do
     # Avoid warnings about HashDict being deprecated.
     module = String.to_atom("HashDict")
@@ -284,6 +291,9 @@ defimpl Enumerable, for: HashDict do
 end
 
 defimpl Collectable, for: HashDict do
+  @moduledoc false
+  @moduledoc deprecated: "Use Map instead"
+
   def into(original) do
     # Avoid warnings about HashDict being deprecated.
     module = String.to_atom("HashDict")
@@ -299,6 +309,8 @@ defimpl Collectable, for: HashDict do
 end
 
 defimpl Inspect, for: HashDict do
+  @moduledoc false
+  @moduledoc deprecated: "Use Map instead"
   import Inspect.Algebra
 
   def inspect(dict, opts) do

lib/elixir/lib/hash_set.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule HashSet do
   @moduledoc """
   Tuple-based HashSet implementation.
@@ -270,6 +274,9 @@ defmodule HashSet do
 end
 
 defimpl Enumerable, for: HashSet do
+  @moduledoc false
+  @moduledoc deprecated: "Use MapSet instead"
+
   def reduce(set, acc, fun) do
     # Avoid warnings about HashSet being deprecated.
     module = String.to_atom("HashSet")
@@ -294,6 +301,9 @@ defimpl Enumerable, for: HashSet do
 end
 
 defimpl Collectable, for: HashSet do
+  @moduledoc false
+  @moduledoc deprecated: "Use MapSet instead"
+
   def into(original) do
     # Avoid warnings about HashSet being deprecated.
     module = String.to_atom("HashSet")
@@ -309,6 +319,8 @@ defimpl Collectable, for: HashSet do
 end
 
 defimpl Inspect, for: HashSet do
+  @moduledoc false
+  @moduledoc deprecated: "Use MapSet instead"
   import Inspect.Algebra
 
   def inspect(set, opts) do

lib/elixir/lib/inspect.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 import Kernel, except: [inspect: 1]
 import Inspect.Algebra
 
@@ -60,9 +64,11 @@ defprotocol Inspect do
 
     * `:except` - remove the given fields when inspecting.
 
-    * `:optional` - (since v1.14.0) do not include a field if it
-      matches its default value. This can be used to simplify the
-      struct representation at the cost of hiding information.
+    * `:optional` - (since v1.14.0) a list of fields that should not be
+      included when they match their default value. This can be used to
+      simplify the struct representation at the cost of hiding
+      information. Since v1.19.0, the `:all` atom can be passed to
+      mark all fields as optional.
 
   Whenever `:only` or `:except` are used to restrict fields,
   the struct will be printed using the `#User<...>` notation,
@@ -78,15 +84,25 @@ defprotocol Inspect do
       #=> #User<id: 1, name: "Jane", ...>
 
   If you use only the `:optional` option, the struct will still be
-  printed as `%User{...}`.
+  printed as a valid struct.
+
+      defmodule Point do
+        @derive {Inspect, optional: [:z]}
+        defstruct [x: 0, y: 0, z: 0]
+      end
+
+      inspect(%Point{x: 1})
+      %Point{x: 1, y: 0}
 
   ## Custom implementation
 
   You can also define your custom protocol implementation by
   defining the `inspect/2` function. The function receives the
   entity to be inspected followed by the inspecting options,
-  represented by the struct `Inspect.Opts`. Building of the
-  algebra document is done with `Inspect.Algebra`.
+  represented by the struct `Inspect.Opts` and it must return
+  an algebra document alongside the updated options (or, optionally,
+  just the algebra document). Building of the algebra document
+  is done with `Inspect.Algebra`.
 
   Many times, inspecting a structure can be implemented in function
   of existing entities. For example, here is `MapSet`'s `inspect/2`
@@ -96,16 +112,19 @@ defprotocol Inspect do
         import Inspect.Algebra
 
         def inspect(map_set, opts) do
-          concat(["MapSet.new(", Inspect.List.inspect(MapSet.to_list(map_set), opts), ")"])
+          {doc, opts} = to_doc_with_opts(MapSet.to_list(map_set), opts)
+          {concat(["MapSet.new(", doc, ")"]), opts}
         end
       end
 
-  The [`concat/1`](`Inspect.Algebra.concat/1`) function comes from
-  `Inspect.Algebra` and it concatenates algebra documents together.
+  First [`to_doc_with_opts/2`](`Inspect.Algebra.to_doc_with_opts/2`) is
+  used to convert another data structure into its algebra document and
+  then [`concat/1`](`Inspect.Algebra.concat/1`) concatenates algebra
+  documents together.
+
   In the example above it is concatenating the string `"MapSet.new("`,
-  the document returned by `Inspect.Algebra.to_doc/2`, and the final
-  string `")"`. Therefore, the MapSet with the numbers 1, 2, and 3
-  will be printed as:
+  the document returned by `to_doc_with_opts/2`, and the final string `")"`.
+  Therefore, the MapSet with the numbers 1, 2, and 3 will be printed as:
 
       iex> MapSet.new([1, 2, 3], fn x -> x * 2 end)
       MapSet.new([2, 4, 6])
@@ -134,6 +153,9 @@ defprotocol Inspect do
 
           Inspect.MapSet.inspect(MapSet.new(), %Inspect.Opts{})
 
+      Note that, from Elixir v1.19, the inspect protocol was augmented to
+      allow a two-element tuple with the document and the updated options
+      to be returned from the protocol.
   """
 
   # Handle structs in Any
@@ -146,11 +168,19 @@ defprotocol Inspect do
 
     only = Keyword.get(options, :only, fields)
     except = Keyword.get(options, :except, [])
-    optional = Keyword.get(options, :optional, [])
 
     :ok = validate_option(:only, only, fields, module)
     :ok = validate_option(:except, except, fields, module)
-    :ok = validate_option(:optional, optional, fields, module)
+
+    optional =
+      case Keyword.get(options, :optional, []) do
+        :all ->
+          fields
+
+        optional ->
+          :ok = validate_option(:optional, optional, fields, module)
+          optional
+      end
 
     inspect_module =
       if fields == Enum.sort(only) and except == [] do
@@ -200,13 +230,26 @@ defprotocol Inspect do
                 do: var!(info)
 
           var!(name) = Macro.inspect_atom(:literal, unquote(module))
-          unquote(inspect_module).inspect(var!(struct), var!(name), var!(infos), var!(opts))
+
+          unquote(inspect_module).inspect_as_struct(
+            var!(struct),
+            var!(name),
+            var!(infos),
+            var!(opts)
+          )
         end
       end
     end
   end
 
   defp validate_option(option, option_list, fields, module) do
+    if not is_list(option_list) do
+      raise ArgumentError,
+            "invalid value #{Kernel.inspect(option_list)} in #{Kernel.inspect(option)} " <>
+              "when deriving the Inspect protocol for #{Kernel.inspect(module)} " <>
+              "(expected a list)"
+    end
+
     case option_list -- fields do
       [] ->
         :ok
@@ -226,7 +269,8 @@ defprotocol Inspect do
   `Inspect.Algebra.to_doc/2` should be preferred as it handles structs
   and exceptions.
   """
-  @spec inspect(t, Inspect.Opts.t()) :: Inspect.Algebra.t()
+  @spec inspect(t, Inspect.Opts.t()) ::
+          Inspect.Algebra.t() | {Inspect.Algebra.t(), Inspect.Opts.t()}
   def inspect(term, opts)
 end
 
@@ -268,11 +312,13 @@ defimpl Inspect, for: BitString do
     color_doc("<<>>", :binary, opts)
   end
 
-  defp inspect_bitstring(bitstring, opts) do
+  defp inspect_bitstring(bitstring, %{limit: limit} = opts) do
     left = color_doc("<<", :binary, opts)
     right = color_doc(">>", :binary, opts)
-    inner = each_bit(bitstring, opts.limit, opts)
-    group(concat(concat(left, nest(inner, 2)), right))
+    inner = each_bit(bitstring, limit, opts)
+    doc = group(concat(concat(left, nest(inner, 2)), right))
+    new_limit = if limit == :infinity, do: limit, else: max(0, limit - byte_size(bitstring))
+    {doc, %{opts | limit: new_limit}}
   end
 
   defp each_bit(_, 0, _) do
@@ -280,7 +326,7 @@ defimpl Inspect, for: BitString do
   end
 
   defp each_bit(<<>>, _counter, _opts) do
-    :doc_nil
+    Inspect.Algebra.empty()
   end
 
   defp each_bit(<<h::8>>, _counter, opts) do
@@ -353,17 +399,21 @@ defimpl Inspect, for: List do
         color_doc(IO.iodata_to_binary(inspected), :charlist, opts)
 
       keyword?(term) ->
-        container_doc(open, term, close, opts, &keyword/2, separator: sep, break: :strict)
+        container_doc_with_opts(open, term, close, opts, &keyword/2,
+          separator: sep,
+          break: :strict
+        )
 
       true ->
-        container_doc(open, term, close, opts, &to_doc/2, separator: sep)
+        container_doc_with_opts(open, term, close, opts, &to_doc_with_opts/2, separator: sep)
     end
   end
 
   @doc false
   def keyword({key, value}, opts) do
     key = color_doc(Macro.inspect_atom(:key, key), :atom, opts)
-    concat(key, concat(" ", to_doc(value, opts)))
+    {doc, opts} = to_doc_with_opts(value, opts)
+    {concat(key, concat(" ", doc)), opts}
   end
 
   @doc false
@@ -384,12 +434,24 @@ defimpl Inspect, for: Tuple do
     sep = color_doc(",", :tuple, opts)
     close = color_doc("}", :tuple, opts)
     container_opts = [separator: sep, break: :flex]
-    container_doc(open, Tuple.to_list(tuple), close, opts, &to_doc/2, container_opts)
+
+    container_doc_with_opts(
+      open,
+      Tuple.to_list(tuple),
+      close,
+      opts,
+      &to_doc_with_opts/2,
+      container_opts
+    )
   end
 end
 
 defimpl Inspect, for: Map do
   def inspect(map, opts) do
+    inspect_as_map(map, opts)
+  end
+
+  def inspect_as_map(map, opts) do
     list =
       if Keyword.get(opts.custom_options, :sort_maps) do
         map |> Map.to_list() |> :lists.sort()
@@ -408,20 +470,22 @@ defimpl Inspect, for: Map do
     map_container_doc(list, "", opts, fun)
   end
 
-  def inspect(map, name, infos, opts) do
+  def inspect_as_struct(map, name, infos, opts) do
     fun = fn %{field: field}, opts -> Inspect.List.keyword({field, Map.get(map, field)}, opts) end
     map_container_doc(infos, name, opts, fun)
   end
 
   defp to_assoc({key, value}, opts, sep) do
-    concat(concat(to_doc(key, opts), sep), to_doc(value, opts))
+    {key_doc, opts} = to_doc_with_opts(key, opts)
+    {value_doc, opts} = to_doc_with_opts(value, opts)
+    {concat(concat(key_doc, sep), value_doc), opts}
   end
 
   defp map_container_doc(list, name, opts, fun) do
     open = color_doc("%" <> name <> "{", :map, opts)
     sep = color_doc(",", :map, opts)
     close = color_doc("}", :map, opts)
-    container_doc(open, list, close, opts, fun, separator: sep, break: :strict)
+    container_doc_with_opts(open, list, close, opts, fun, separator: sep, break: :strict)
   end
 end
 
@@ -479,9 +543,9 @@ defimpl Inspect, for: Regex do
       :error ->
         concat([
           "Regex.compile!(",
-          Inspect.BitString.inspect(regex.source, opts),
+          to_doc(regex.source, opts),
           ", ",
-          Inspect.List.inspect(regex_opts, opts),
+          to_doc(regex_opts, opts),
           ")"
         ])
 
@@ -505,6 +569,7 @@ defimpl Inspect, for: Regex do
   defp translate_options([:firstline | t], acc), do: translate_options(t, [?f | acc])
   defp translate_options([:ungreedy | t], acc), do: translate_options(t, [?U | acc])
   defp translate_options([:multiline | t], acc), do: translate_options(t, [?m | acc])
+  defp translate_options([:export | t], acc), do: translate_options(t, [?E | acc])
   defp translate_options([], acc), do: acc
   defp translate_options(_t, _acc), do: :error
 
@@ -577,36 +642,6 @@ defimpl Inspect, for: Function do
   end
 end
 
-defimpl Inspect, for: Inspect.Error do
-  @impl true
-  def inspect(%{stacktrace: stacktrace} = inspect_error, _opts) do
-    message = Exception.message(inspect_error)
-    format_output(message, stacktrace)
-  end
-
-  defp format_output(message, [_ | _] = stacktrace) do
-    stacktrace = Exception.format_stacktrace(stacktrace)
-
-    """
-    #Inspect.Error<
-    #{Inspect.Error.pad(message, 2)}
-
-      Stacktrace:
-
-    #{stacktrace}
-    >\
-    """
-  end
-
-  defp format_output(message, []) do
-    """
-    #Inspect.Error<
-      #{Inspect.Error.pad(message, 2)}
-    >\
-    """
-  end
-end
-
 defimpl Inspect, for: PID do
   def inspect(pid, _opts) do
     "#PID" <> IO.iodata_to_binary(:erlang.pid_to_list(pid))
@@ -628,26 +663,15 @@ end
 
 defimpl Inspect, for: Any do
   def inspect(%module{} = struct, opts) do
-    try do
-      {module.__struct__(), module.__info__(:struct)}
-    rescue
-      _ -> Inspect.Map.inspect(struct, opts)
-    else
-      {dunder, fields} ->
-        if Map.keys(dunder) == Map.keys(struct) do
-          infos =
-            for %{field: field} = info <- fields,
-                field not in [:__struct__, :__exception__],
-                do: info
+    info =
+      for %{field: field} = map <- module.__info__(:struct),
+          field != :__exception__,
+          do: map
 
-          Inspect.Map.inspect(struct, Macro.inspect_atom(:literal, module), infos, opts)
-        else
-          Inspect.Map.inspect(struct, opts)
-        end
-    end
+    Inspect.Map.inspect_as_struct(struct, Macro.inspect_atom(:literal, module), info, opts)
   end
 
-  def inspect(map, name, infos, opts) do
+  def inspect_as_struct(map, name, infos, opts) do
     open = color_doc("#" <> name <> "<", :map, opts)
     sep = color_doc(",", :map, opts)
     close = color_doc(">", :map, opts)
@@ -661,6 +685,25 @@ defimpl Inspect, for: Any do
   end
 end
 
+defimpl Inspect, for: Range do
+  import Inspect.Algebra
+  import Kernel, except: [inspect: 2]
+
+  def inspect(first..last//1, opts) when last >= first do
+    concat([to_doc(first, opts), "..", to_doc(last, opts)])
+  end
+
+  def inspect(first..last//step, opts) do
+    concat([to_doc(first, opts), "..", to_doc(last, opts), "//", to_doc(step, opts)])
+  end
+
+  # TODO: Remove me on v2.0
+  def inspect(%{__struct__: Range, first: first, last: last} = range, opts) do
+    step = if first <= last, do: 1, else: -1
+    inspect(Map.put(range, :step, step), opts)
+  end
+end
+
 require Protocol
 
 Protocol.derive(

lib/elixir/lib/inspect/error.ex

@@ -0,0 +1,90 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+
+defmodule Inspect.Error do
+  @moduledoc """
+  Raised when a struct cannot be inspected.
+  """
+  @enforce_keys [:exception_module, :exception_message, :stacktrace, :inspected_struct]
+  defexception @enforce_keys
+
+  @impl true
+  def exception(arguments) when is_list(arguments) do
+    exception = Keyword.fetch!(arguments, :exception)
+    exception_module = exception.__struct__
+    exception_message = Exception.message(exception) |> String.trim_trailing("\n")
+    stacktrace = Keyword.fetch!(arguments, :stacktrace)
+    inspected_struct = Keyword.fetch!(arguments, :inspected_struct)
+
+    %Inspect.Error{
+      exception_module: exception_module,
+      exception_message: exception_message,
+      stacktrace: stacktrace,
+      inspected_struct: inspected_struct
+    }
+  end
+
+  @impl true
+  def message(%__MODULE__{
+        exception_module: exception_module,
+        exception_message: exception_message,
+        inspected_struct: inspected_struct
+      }) do
+    ~s'''
+    got #{inspect(exception_module)} with message:
+
+        """
+    #{pad(exception_message, 4)}
+        """
+
+    while inspecting:
+
+    #{pad(inspected_struct, 4)}
+    '''
+  end
+
+  @doc false
+  def pad(message, padding_length)
+      when is_binary(message) and is_integer(padding_length) and padding_length >= 0 do
+    padding = String.duplicate(" ", padding_length)
+
+    message
+    |> String.split("\n")
+    |> Enum.map(fn
+      "" -> "\n"
+      line -> [padding, line, ?\n]
+    end)
+    |> IO.iodata_to_binary()
+    |> String.trim_trailing("\n")
+  end
+end
+
+defimpl Inspect, for: Inspect.Error do
+  @impl true
+  def inspect(%{stacktrace: stacktrace} = inspect_error, _opts) do
+    message = Exception.message(inspect_error)
+    format_output(message, stacktrace)
+  end
+
+  defp format_output(message, [_ | _] = stacktrace) do
+    stacktrace = Exception.format_stacktrace(stacktrace)
+
+    """
+    #Inspect.Error<
+    #{Inspect.Error.pad(message, 2)}
+
+      Stacktrace:
+
+    #{stacktrace}
+    >\
+    """
+  end
+
+  defp format_output(message, []) do
+    """
+    #Inspect.Error<
+      #{Inspect.Error.pad(message, 2)}
+    >\
+    """
+  end
+end

lib/elixir/lib/integer.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule Integer do
   @moduledoc """
   Functions for working with integers.

lib/elixir/lib/io.ex

@@ -1,3 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2021 The Elixir Team
+# SPDX-FileCopyrightText: 2012 Plataformatec
+
 defmodule IO do
   @moduledoc ~S"""
   Functions handling input/output (IO).
@@ -124,10 +128,26 @@ defmodule IO do
   @type nodata :: {:error, term} | :eof
   @type chardata :: String.t() | maybe_improper_list(char | chardata, String.t() | [])
 
+  @type inspect_opts :: [Inspect.Opts.new_opt() | {:label, term}]
+
+  @typedoc """
+  Stacktrace information as keyword options for `warn/2`.
+
+  At least `:file` is required. Other options are optional and used
+  to provide more precise location information.
+  """
+  @type warn_stacktrace_opts :: [
+          file: String.t(),
+          line: pos_integer(),
+          column: pos_integer(),
+          module: module(),
+          function: {atom(), arity()}
+        ]
+
   defguardp is_device(term) when is_atom(term) or is_pid(term)
   defguardp is_iodata(data) when is_list(data) or is_binary(data)
 
-  @doc """
+  @doc ~S"""
   Reads from the IO `device`.
 
   The `device` is iterated as specified by the `line_or_chars` argument:
@@ -137,7 +157,7 @@ defmodule IO do
       non-textual inputs.
 
     * if `line_or_chars` is `:line`, the device is iterated line by line.
-      CRFL newlines  ("\r\n") are automatically normalized to "\n".
+      CRLF newlines  ("\r\n") are automatically normalized to "\n".
 
     * if `line_or_chars` is `:eof` (since v1.13), the device is iterated until `:eof`.
       If the device is already at the end, it returns `:eof` itself.
@@ -182,7 +202,7 @@ defmodule IO do
     :io.get_chars(map_dev(device), ~c"", count)
   end
 
-  @doc """
+  @doc ~S"""
   Reads from the IO `device`. The operation is Unicode unsafe.
 
   The `device` is iterated as specified by the `line_or_chars` argument:
@@ -192,7 +212,7 @@ defmodule IO do
       non-textual inputs.
 
     * if `line_or_chars` is `:line`, the device is iterated line by line.
-      CRFL newlines  ("\r\n") are automatically normalized to "\n".
+      CRLF newlines  ("\r\n") are automatically normalized to "\n".
 
     * if `line_or_chars` is `:eof` (since v1.13), the device is iterated until `:eof`.
       If the device is already at the end, it returns `:eof` itself.
@@ -342,7 +362,10 @@ defmodule IO do
       #=>   my_app.ex:4: MyApp.main/1
 
   """
-  @spec warn(chardata | String.Chars.t(), Exception.stacktrace() | keyword() | Macro.Env.t()) ::
+  @spec warn(
+          chardata | String.Chars.t(),
+          Exception.stacktrace() | warn_stacktrace_opts() | Macro.Env.t()
+        ) ::
           :ok
   def warn(message, stacktrace_info)
 
@@ -444,13 +467,15 @@ defmodule IO do
 
   ## Examples
 
+  The following code:
+
       IO.inspect(<<0, 1, 2>>, width: 40)
 
   Prints:
 
       <<0, 1, 2>>
 
-  We can use the `:label` option to decorate the output:
+  You can use the `:label` option to decorate the output:
 
       IO.inspect(1..100, label: "a wonderful range")
 
@@ -458,21 +483,23 @@ defmodule IO do
 
       a wonderful range: 1..100
 
-  The `:label` option is especially useful with pipelines:
+  Inspect truncates large inputs by default. The `:printable_limit` controls
+  the limit for strings and other string-like constructs (such as charlists):
 
-      [1, 2, 3]
-      |> IO.inspect(label: "before")
-      |> Enum.map(&(&1 * 2))
-      |> IO.inspect(label: "after")
-      |> Enum.sum()
+      "abc"
+      |> String.duplicate(9001)
+      |> IO.inspect(printable_limit: :infinity)
 
-  Prints:
+  For containers such as lists, maps, and tuples, the number of entries
+  is managed by the `:limit` option:
 
-      before: [1, 2, 3]
-      after: [2, 4, 6]
+      1..100
+      |> Enum.map(& {&1, &1})
+      |> Enum.into(%{})
+      |> IO.inspect(limit: :infinity)
 
   """
-  @spec inspect(item, keyword) :: item when item: var
+  @spec inspect(item, inspect_opts) :: item when item: var
   def inspect(item, opts \\ []) do
     inspect(:stdio, item, opts)
   end
@@ -482,9 +509,10 @@ defmodule IO do
 
   See `inspect/2` for a full list of options.
   """
-  @spec inspect(device, item, keyword) :: item when item: var
+  @spec inspect(device, item, inspect_opts) :: item when item: var
   def inspect(device, item, opts) when is_device(device) and is_list(opts) do
-    label = if label = opts[:label], do: [to_chardata(label), ": "], else: []
+    {label, opts} = Keyword.pop(opts, :label)
+    label = if label, do: [to_chardata(label), ": "], else: []
     opts = Inspect.Opts.new(opts)
     doc = Inspect.Algebra.group(Inspect.Algebra.to_doc(item, opts))
     chardata = Inspect.Algebra.format(doc, opts.width)
@@ -599,7 +627,7 @@ defmodule IO do
   @spec stream() :: Enumerable.t(String.t())
   def stream, do: stream(:stdio, :line)
 
-  @doc """
+  @doc ~S"""
   Converts the IO `device` into an `IO.Stream`.
 
   An `IO.Stream` implements both `Enumerable` and
@@ -628,11 +656,11 @@ defmodule IO do
 
   Another example where you might want to collect a user input
   every new line and break on an empty line, followed by removing
-  redundant new line characters (`"\\n"`):
+  redundant new line characters (`"\n"`):
 
       IO.stream(:stdio, :line)
-      |> Enum.take_while(&(&1 != "\\n"))
-      |> Enum.map(&String.replace(&1, "\\n", ""))
+      |> Enum.take_while(&(&1 != "\n"))
+      |> Enum.map(&String.replace(&1, "\n", ""))
 
   """
   @spec stream(device, :line | pos_integer) :: Enumerable.t()
@@ -654,7 +682,7 @@ defmodule IO do
   @spec binstream() :: Enumerable.t(binary)
   def binstream, do: binstream(:stdio, :line)
 
-  @doc """
+  @doc ~S"""
   Converts the IO `device` into an `IO.Stream`. The operation is Unicode unsafe.
 
   An `IO.Stream` implements both `Enumerable` and