Release v1.19.3

Closes #14900.

CHANGELOG.md

@@ -234,6 +234,34 @@ These additions offer greater transparency into the components and licenses of e
 
 This work was performed by [Jonatan Männchen](https://maennchen.dev) and sponsored by the [Erlang Ecosystem Foundation](https://erlef.org).
 
+## v1.19.3 (2025-11-13)
+
+### 1. Enhancements
+
+#### Elixir
+
+  * [Kernel] Support /E modifier for regular expressions in config files
+
+#### Mix
+
+  * [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
+
+  * [IO] Fix dialyzer warning on `IO.inspect :label`
+
+#### ExUnit
+
+  * [ExUnit.Case] Fix crash when formatting errors caused by a linked/trapped exit during `setup_all`
+
+#### Mix
+
+  * [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
+
 ## v1.19.2 (2025-11-02)
 
 ### 1. Enhancements

VERSION

@@ -1 +1 @@
-1.19.2
+1.19.3

bin/elixir

@@ -6,7 +6,7 @@
 
 set -e
 
-ELIXIR_VERSION=1.19.2
+ELIXIR_VERSION=1.19.3
 
 if [ $# -eq 0 ] || { [ $# -eq 1 ] && { [ "$1" = "--help" ] || [ "$1" = "-h" ]; }; }; then
   cat <<USAGE >&2

bin/elixir.bat

@@ -4,7 +4,7 @@
 :: SPDX-FileCopyrightText: 2021 The Elixir Team
 :: SPDX-FileCopyrightText: 2012 Plataformatec
 
-set ELIXIR_VERSION=1.19.2
+set ELIXIR_VERSION=1.19.3
 
 if    ""%1""==""""                if ""%2""=="""" goto documentation
 if /I ""%1""==""--help""          if ""%2""=="""" goto documentation

lib/elixir/lib/inspect.ex

@@ -569,6 +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
 

lib/elixir/lib/regex.ex

@@ -101,6 +101,13 @@ defmodule Regex do
     * `:ungreedy` (U) - inverts the "greediness" of the regexp
       (the previous `r` option is deprecated in favor of `U`)
 
+    * `:export` (E) (since Elixir 1.20) - uses an exported pattern
+      which can be shared across nodes or through config, at the cost of a runtime
+      overhead every time to re-import it every time it is executed.
+      This modifier only has an effect starting on Erlang/OTP 28, and it is ignored
+      on older versions (i.e. `~r/foo/E == ~r/foo/`). This is because patterns cannot
+      and do not need to be exported in order to be shared in these versions.
+
   ## Captures
 
   Many functions in this module handle what to capture in a regex
@@ -251,7 +258,7 @@ defmodule Regex do
   This checks the version stored in the regular expression
   and recompiles the regex in case of version mismatch.
   """
-  # Remove me on Elixir v1.22
+  # TODO: Deprecate on Elixir v1.22
   @doc deprecated: "It can be removed and it has no effect"
   @doc since: "1.4.0"
   def recompile(%Regex{} = regex) do
@@ -261,7 +268,7 @@ defmodule Regex do
   @doc """
   Recompiles the existing regular expression and raises `Regex.CompileError` in case of errors.
   """
-  # Remove me on Elixir v1.22
+  # TODO: Deprecate on Elixir v1.22
   @doc deprecated: "It can be removed and it has no effect"
   @doc since: "1.4.0"
   def recompile!(regex) do
@@ -271,7 +278,7 @@ defmodule Regex do
   @doc """
   Returns the version of the underlying Regex engine.
   """
-  # Remove me on Elixir v1.22
+  # TODO: Deprecate on Elixir v1.22
   @doc deprecated: "Use :re.version() instead"
   @doc since: "1.4.0"
   def version do
@@ -515,7 +522,7 @@ defmodule Regex do
   """
   @spec names(t) :: [String.t()]
   def names(%Regex{re_pattern: re_pattern}) do
-    {:namelist, names} = :re.inspect(re_pattern, :namelist)
+    {:namelist, names} = :re.inspect(maybe_import_pattern(re_pattern), :namelist)
     names
   end
 
@@ -585,10 +592,16 @@ defmodule Regex do
       %Regex{source: source, opts: compile_opts} = regex
       :re.run(string, source, compile_opts ++ options)
     else
-      _ -> :re.run(string, re_pattern, options)
+      _ -> :re.run(string, maybe_import_pattern(re_pattern), options)
     end
   end
 
+  @compile {:inline, maybe_import_pattern: 1}
+  defp maybe_import_pattern({:re_exported_pattern, _, _, _, _} = exported),
+    do: :re.import(exported)
+
+  defp maybe_import_pattern(pattern), do: pattern
+
   @typedoc """
   Options for regex functions that capture matches.
   """
@@ -1007,6 +1020,16 @@ defmodule Regex do
     translate_options(t, [:ungreedy | acc])
   end
 
+  defp translate_options(<<?E, t::binary>>, acc) do
+    # on OTP 27-, the E modifier is a no-op since the feature doesn't exist but isn't needed
+    # (regexes aren't using references and can be shared across nodes or stored in config)
+    # TODO: remove this check on Erlang/OTP 28+ and update docs
+    case Code.ensure_loaded?(:re) and function_exported?(:re, :import, 1) do
+      true -> translate_options(t, [:export | acc])
+      false -> translate_options(t, acc)
+    end
+  end
+
   defp translate_options(<<>>, acc), do: acc
   defp translate_options(t, _acc), do: {:error, t}
 
@@ -1022,6 +1045,9 @@ defmodule Regex do
         :erlang.system_info(:otp_release) < [?2, ?8] ->
           Macro.escape(regex.re_pattern)
 
+        :lists.member(:export, regex.opts) ->
+          Macro.escape(regex.re_pattern)
+
         # OTP 28.1+ introduced the ability to export and import regexes from compiled binaries
         Code.ensure_loaded?(:re) and function_exported?(:re, :import, 1) ->
           {:ok, exported} = :re.compile(regex.source, [:export] ++ regex.opts)

lib/elixir/test/elixir/inspect_test.exs

@@ -906,6 +906,11 @@ defmodule Inspect.OthersTest do
     assert inspect(Regex.compile!("foo", [:ucp])) == ~S'Regex.compile!("foo", [:ucp])'
   end
 
+  @tag :re_import
+  test "exported regex" do
+    assert inspect(~r/foo/E) == "~r/foo/E"
+  end
+
   test "inspect_fun" do
     fun = fn
       integer, _opts when is_integer(integer) ->

lib/elixir/test/elixir/regex_test.exs

@@ -52,6 +52,20 @@ defmodule RegexTest do
     assert Regex.match?(~r/^b$/m, "a\nb\nc")
   end
 
+  @tag :re_import
+  test "export" do
+    # exported patterns have no structs, so these are structurally equal
+    assert ~r/foo/E == Regex.compile!("foo", [:export])
+
+    assert Regex.match?(~r/foo/E, "foo")
+    refute Regex.match?(~r/foo/E, "Foo")
+
+    assert Regex.run(~r/c(d)/E, "abcd") == ["cd", "d"]
+    assert Regex.run(~r/e/E, "abcd") == nil
+
+    assert Regex.names(~r/(?<FOO>foo)/E) == ["FOO"]
+  end
+
   test "precedence" do
     assert {"aa", :unknown} |> elem(0) =~ ~r/(a)\1/
   end

lib/ex_unit/lib/ex_unit/formatter.ex

@@ -338,7 +338,8 @@ defmodule ExUnit.Formatter do
         {formatted_reason, wrapped_stack} =
           format_exception(test, struct, wrapped_stack, width, formatter, @counter_padding)
 
-        formatted_stack = format_stacktrace(wrapped_stack, test.module, test.name, formatter)
+        formatted_stack = format_stacktrace(wrapped_stack, test, formatter)
+
         {error_info(header, formatter) <> pad(formatted_reason <> formatted_stack), stack}
 
       :error ->
@@ -672,22 +673,28 @@ defmodule ExUnit.Formatter do
     |> Algebra.format(width)
   end
 
-  defp format_stacktrace([], _case, _test, _color) do
+  defp format_stacktrace(stack, %{module: module, name: name}, color),
+    do: format_stacktrace(stack, module, name, color)
+
+  defp format_stacktrace(stack, %{name: name}, color),
+    do: format_stacktrace(stack, name, nil, color)
+
+  defp format_stacktrace([], _module, _test, _color) do
     ""
   end
 
-  defp format_stacktrace(stacktrace, test_case, test, color) do
+  defp format_stacktrace(stacktrace, module, test, color) do
     extra_info("stacktrace:", color) <>
       Enum.map_join(stacktrace, fn entry ->
-        stacktrace_info(format_stacktrace_entry(entry, test_case, test), color)
+        stacktrace_info(format_stacktrace_entry(entry, module, test), color)
       end)
   end
 
-  defp format_stacktrace_entry({test_case, test, _, location}, test_case, test) do
+  defp format_stacktrace_entry({module, test, _, location}, module, test) do
     format_file_line(location[:file], location[:line], " (test)")
   end
 
-  defp format_stacktrace_entry(entry, _test_case, _test) do
+  defp format_stacktrace_entry(entry, _module, _test) do
     format_stacktrace_entry(entry)
   end
 

lib/ex_unit/test/ex_unit/formatter_test.exs

@@ -465,6 +465,21 @@ defmodule ExUnit.FormatterTest do
            """
   end
 
+  test "formats setup_all exit stacktraces using module context" do
+    stacktrace = [
+      {Hello, :setup_all, [], [file: __ENV__.file, line: 123]},
+      {Hello, :some_fun, [], [file: __ENV__.file, line: 456]}
+    ]
+
+    failure = [{{:EXIT, self()}, {:function_clause, stacktrace}, []}]
+
+    formatted =
+      format_test_all_failure(test_module(), failure, 1, 80, &formatter/2)
+
+    assert formatted =~ "Hello.setup_all/0"
+    assert formatted =~ "Hello.some_fun()"
+  end
+
   test "formats assertions with operators with no limit" do
     failure = [{:error, catch_assertion(assert [1, 2, 3] == [4, 5, 6]), []}]
 

lib/mix/lib/mix/release.ex

@@ -468,51 +468,48 @@ defmodule Mix.Release do
     {sys_config, runtime_config?} =
       merge_provider_config(release, sys_config, config_provider_path)
 
-    path = Path.join(release.version_path, "sys.config")
-
-    args = [runtime_config?, sys_config]
-    format = "%% coding: utf-8~n%% RUNTIME_CONFIG=~s~n~tw.~n"
-    File.mkdir_p!(Path.dirname(path))
-    File.write!(path, IO.chardata_to_string(:io_lib.format(format, args)))
-
-    case :file.consult(path) do
-      {:ok, _} ->
+    case consultable_sys_config(sys_config) do
+      {:ok, contents} ->
+        path = Path.join(release.version_path, "sys.config")
+        args = [runtime_config?, contents]
+        format = "%% coding: utf-8~n%% RUNTIME_CONFIG=~s~n~ts.~n"
+        File.mkdir_p!(Path.dirname(path))
+        File.write!(path, IO.chardata_to_string(:io_lib.format(format, args)))
         :ok
 
-      {:error, reason} ->
-        invalid =
-          for {app, kv} <- sys_config,
-              {key, value} <- kv,
-              not valid_config?(value),
-              do: """
-
-              Application: #{inspect(app)}
-              Key: #{inspect(key)}
-              Value: #{inspect(value)}
-              """
-
-        message =
-          case invalid do
-            [] ->
-              "Could not read configuration file. Reason: #{inspect(reason)}"
-
-            _ ->
-              "Could not read configuration file. It has invalid configuration terms " <>
-                "such as functions, references, and pids. Please make sure your configuration " <>
-                "is made of numbers, atoms, strings, maps, tuples and lists. The following entries " <>
-                "are wrong:\n#{Enum.join(invalid)}"
-          end
-
+      {:error, message} ->
         {:error, message}
     end
   end
 
-  defp valid_config?(m) when is_map(m),
-    do: Enum.all?(Map.delete(m, :__struct__), &valid_config?/1)
+  defp consultable_sys_config(sys_config) do
+    contents =
+      Enum.map_intersperse(sys_config, ?,, fn {app, kv} ->
+        kv =
+          Enum.map_intersperse(kv, ?,, fn {key, value} ->
+            case Mix.Utils.consultable(value) do
+              {:ok, value} -> [?{, :io_lib.print(key), ?,, value, ?}]
+              {:error, term, reason} -> throw({:error, app, key, term, reason})
+            end
+          end)
 
-  defp valid_config?(l) when is_list(l), do: Enum.all?(l, &valid_config?/1)
-  defp valid_config?(t) when is_tuple(t), do: Enum.all?(Tuple.to_list(t), &valid_config?/1)
-  defp valid_config?(o), do: is_number(o) or is_atom(o) or is_binary(o)
+        [?{, :io_lib.print(app), ?,, ?[, kv, ?], ?}]
+      end)
+
+    {:ok, [?[, contents, ?]]}
+  catch
+    {:error, app, key, value, reason} ->
+      message = """
+      Could not write configuration file because it has invalid terms
+
+      Application: #{inspect(app)}
+      Key: #{inspect(key)}
+      Invalid value: #{inspect(value)}
+      Reason: #{reason}
+      """
+
+      {:error, message}
+  end
 
   defp merge_provider_config(%{config_providers: []}, sys_config, _), do: {sys_config, false}
 

lib/mix/lib/mix/task.compiler.ex

@@ -295,10 +295,24 @@ defmodule Mix.Task.Compiler do
   end
 
   defp run_compiler(compiler, args) do
-    result = normalize(Mix.Task.run("compile.#{compiler}", args), compiler)
+    args_maybe_force = maybe_prepend_force(args, compiler)
+    result = normalize(Mix.Task.run("compile.#{compiler}", args_maybe_force), compiler)
     Enum.reduce(Mix.ProjectStack.pop_after_compiler(compiler), result, & &1.(&2))
   end
 
+  defp maybe_prepend_force(args, compiler) do
+    args
+    |> Enum.any?(fn
+      "--force-" <> rest -> rest == compiler |> to_string() |> String.replace("_", "-")
+      _ -> false
+    end)
+    |> if do
+      ["--force" | args]
+    else
+      args
+    end
+  end
+
   # Normalize the compiler result to a diagnostic tuple
   defp normalize(result, name) do
     case result do

lib/mix/lib/mix/tasks/compile.app.ex

@@ -187,12 +187,22 @@ defmodule Mix.Tasks.Compile.App do
         |> add_compile_env(current_properties)
         |> add_modules(modules, compile_path)
 
-      contents = to_erl_term({:application, app, properties})
+      contents =
+        case Mix.Utils.consultable({:application, app, properties}) do
+          {:ok, contents} ->
+            contents
+
+          {:error, term, reason} ->
+            Mix.raise(
+              "\"def application\" has a term which cannot be written to .app files: #{inspect(term)} (#{reason})"
+            )
+        end
+
       :application.unload(app)
       :application.load({:application, app, properties})
 
       Mix.Project.ensure_structure()
-      File.write!(target, [contents, ?.])
+      File.write!(target, IO.chardata_to_string([contents, ?.]))
       File.touch!(target, new_mtime)
 
       # If we just created the .app file, it will have touched
@@ -209,53 +219,6 @@ defmodule Mix.Tasks.Compile.App do
     end
   end
 
-  defp to_erl_term(tuple) when is_tuple(tuple) do
-    [?{, tuple |> Tuple.to_list() |> to_erl_head(), ?}]
-  end
-
-  defp to_erl_term(list) when is_list(list) do
-    [?[, to_erl_head(list), ?]]
-  end
-
-  defp to_erl_term(map) when is_map(map) do
-    inner =
-      Enum.map_intersperse(
-        :maps.to_list(:maps.iterator(map, :reversed)),
-        ?,,
-        fn {key, value} -> [to_erl_term(key), "=>", to_erl_term(value)] end
-      )
-
-    [?#, ?{, inner, ?}]
-  end
-
-  defp to_erl_term(map) when is_map(map) do
-    inner =
-      Enum.map_intersperse(
-        :maps.to_list(:maps.iterator(map, :reversed)),
-        ?,,
-        fn {key, value} -> [to_erl_term(key), "=>", to_erl_term(value)] end
-      )
-
-    [?#, ?{, inner, ?}]
-  end
-
-  defp to_erl_term(term) when is_function(term) or is_reference(term) or is_pid(term) do
-    Mix.raise(
-      "\"def application\" has a term which cannot be written to .app files: #{inspect(term)}"
-    )
-  end
-
-  defp to_erl_term(term) do
-    :io_lib.print(term)
-  end
-
-  defp to_erl_head([]), do: []
-  defp to_erl_head([h | t]), do: [to_erl_term(h) | to_erl_tail(t)]
-
-  defp to_erl_tail([h | t]), do: [?,, to_erl_term(h) | to_erl_tail(t)]
-  defp to_erl_tail([]), do: []
-  defp to_erl_tail(other), do: [?|, to_erl_term(other)]
-
   defp current_app_properties(target) do
     case :file.consult(target) do
       {:ok, [{:application, _app, properties}]} -> properties

lib/mix/lib/mix/tasks/compile.ex

@@ -7,7 +7,7 @@ defmodule Mix.Tasks.Compile do
 
   @shortdoc "Compiles source files"
 
-  @moduledoc """
+  @moduledoc ~S"""
   The main entry point to compile source files.
 
   It simply runs the compilers registered in your project and returns
@@ -59,7 +59,9 @@ defmodule Mix.Tasks.Compile do
     * `--all-warnings` (`--no-all-warnings`) - prints all warnings, including previous compilations
       (default is true except on errors)
     * `--erl-config` - path to an Erlang term file that will be loaded as Mix config
-    * `--force` - forces compilation
+    * `--force` - forces compilation. You can also specify `--force-#{compiler}` for each compiler
+      invoked to force specifically that compiler to run (it requires the compiler to respect the
+      `--force` option, which is advised)
     * `--list` - lists all enabled compilers
     * `--listeners` - starts Mix listeners (they are started by default,
       unless `--no-listeners` or `--no-deps-check` are given)

lib/mix/lib/mix/tasks/help.ex

@@ -114,10 +114,19 @@ defmodule Mix.Tasks.Help do
     loadpaths!()
     app = String.to_atom(app)
 
+    # If the application is not available, attempt to load it from Erlang/Elixir
+    if is_nil(Application.spec(app, :vsn)) do
+      try do
+        Mix.ensure_application!(app)
+      rescue
+        _ -> :ok
+      end
+    end
+
     if modules = Application.spec(app, :modules) do
       for module <- modules,
           not (module |> Atom.to_string() |> String.starts_with?("Elixir.Mix.Tasks.")),
-          {:docs_v1, _, :elixir, "text/markdown", %{"en" => <<doc::binary>>}, _, _} <-
+          {:docs_v1, _, _, "text/markdown", %{"en" => <<doc::binary>>}, _, _} <-
             [Code.fetch_docs(module)] do
         leading = doc |> String.split(["\n\n", "\r\n\r\n"], parts: 2) |> hd()
         "# #{inspect(module)}\n#{leading}\n"

lib/mix/lib/mix/utils.ex

@@ -907,4 +907,77 @@ defmodule Mix.Utils do
         uid
     end
   end
+
+  @doc """
+  Convert the given terms to a consultable Erlang term.
+  """
+  def consultable(term) do
+    {:ok, to_erl_term(term)}
+  catch
+    {:error, term, reason} -> {:error, term, reason}
+  end
+
+  defp to_erl_term(tuple) when is_tuple(tuple) do
+    [?{, tuple |> Tuple.to_list() |> to_erl_head(), ?}]
+  end
+
+  defp to_erl_term(list) when is_list(list) do
+    if List.ascii_printable?(list) do
+      :io_lib.print(list)
+    else
+      [?[, to_erl_head(list), ?]]
+    end
+  end
+
+  defp to_erl_term(%Regex{re_pattern: {:re_pattern, _, _, _, ref}} = regex)
+       when is_reference(ref) do
+    throw({:error, regex, "you must use the /E modifier to store regexes"})
+  end
+
+  defp to_erl_term(map) when is_map(map) do
+    inner =
+      Enum.map_intersperse(
+        :maps.to_list(:maps.iterator(map, :reversed)),
+        ?,,
+        fn {key, value} -> [to_erl_term(key), "=>", to_erl_term(value)] end
+      )
+
+    [?#, ?{, inner, ?}]
+  end
+
+  defp to_erl_term(map) when is_map(map) do
+    inner =
+      Enum.map_intersperse(
+        :maps.to_list(:maps.iterator(map, :reversed)),
+        ?,,
+        fn {key, value} -> [to_erl_term(key), "=>", to_erl_term(value)] end
+      )
+
+    [?#, ?{, inner, ?}]
+  end
+
+  defp to_erl_term(function) when is_function(function) do
+    fun_info = Function.info(function)
+
+    if fun_info[:type] == :external and fun_info[:env] == [] do
+      :io_lib.print(function)
+    else
+      throw({:error, function, "only functions in the form &Mod.fun/arity are allowed"})
+    end
+  end
+
+  defp to_erl_term(term) when is_reference(term) or is_pid(term) do
+    throw({:error, term, "PIDs and References are not supported"})
+  end
+
+  defp to_erl_term(term) do
+    :io_lib.print(term)
+  end
+
+  defp to_erl_head([]), do: []
+  defp to_erl_head([h | t]), do: [to_erl_term(h) | to_erl_tail(t)]
+
+  defp to_erl_tail([h | t]), do: [?,, to_erl_term(h) | to_erl_tail(t)]
+  defp to_erl_tail([]), do: []
+  defp to_erl_tail(other), do: [?|, to_erl_term(other)]
 end

lib/mix/test/mix/release_test.exs

@@ -592,19 +592,20 @@ defmodule Mix.ReleaseTest do
       assert make_sys_config(release([]), [foo: [bar: :baz]], "unused/runtime/path") == :ok
       contents = File.read!(@sys_config)
       assert contents =~ "%% RUNTIME_CONFIG=false"
-      assert contents =~ "[{foo,[{bar,baz}]}]."
+      {:ok, contents} = :file.consult(@sys_config)
+      assert contents == [[foo: [bar: :baz]]]
     end
 
     test "writes sys_config with encoding" do
       assert make_sys_config(
                release([]),
-               [encoding: {:_μ, :"£", "£", ~c"£"}],
+               [encoding: [key: {:_μ, :"£", "£", ~c"£"}]],
                "unused/runtime/path"
              ) ==
                :ok
 
       {:ok, contents} = :file.consult(@sys_config)
-      assert contents == [[encoding: {:_μ, :"£", "£", ~c"£"}]]
+      assert contents == [[encoding: [key: {:_μ, :"£", "£", ~c"£"}]]]
     end
 
     test "writes the given sys_config with config providers" do
@@ -649,12 +650,12 @@ defmodule Mix.ReleaseTest do
     end
 
     test "errors on bad config" do
-      assert {:error, "Could not read configuration file." <> _} =
+      assert {:error, "Could not write configuration file " <> _} =
                make_sys_config(release([]), [foo: [bar: self()]], "unused/runtime/path")
 
       env = %{__ENV__ | lexical_tracker: self()}
 
-      assert {:error, "Could not read configuration file." <> _} =
+      assert {:error, "Could not write configuration file " <> _} =
                make_sys_config(release([]), [foo: [bar: env]], "unused/runtime/path")
     end
   end

lib/mix/test/mix/tasks/compile.app_test.exs

@@ -110,7 +110,7 @@ defmodule Mix.Tasks.Compile.AppTest do
   test "uses custom application settings" do
     in_fixture("no_mixfile", fn ->
       Mix.Project.push(CustomProject)
-      env = [foo: [:one, "two", 3, 4], bar: [{} | %{foo: :bar}]]
+      env = [foo: [:one, "two", 3, 4, "฿", &List.flatten/1], bar: [{} | %{foo: :bar}]]
 
       Process.put(:application,
         maxT: :infinity,
@@ -132,7 +132,10 @@ defmodule Mix.Tasks.Compile.AppTest do
       assert properties[:applications] ==
                [:kernel, :stdlib, :elixir, :logger, :ex_unit, :example_app, :mix]
 
-      assert properties[:env] == [foo: [:one, "two", 3, 4], bar: [{} | %{foo: :bar}]]
+      assert properties[:env] == [
+               foo: [:one, "two", 3, 4, "฿", &List.flatten/1],
+               bar: [{} | %{foo: :bar}]
+             ]
 
       refute Keyword.has_key?(properties, :extra_applications)
     end)
@@ -260,6 +263,25 @@ defmodule Mix.Tasks.Compile.AppTest do
     end)
   end
 
+  @tag :re_import
+  test "accepts only regexes without a reference" do
+    in_fixture("no_mixfile", fn ->
+      Mix.Project.push(CustomProject)
+      Process.put(:application, env: [regex: ~r/foo/])
+
+      assert_raise Mix.Error, ~r/you must use the \/E modifier to store regexes/, fn ->
+        Mix.Tasks.Compile.App.run([])
+      end
+
+      Process.put(:application, env: [exported: ~r/foo/E])
+      Mix.Tasks.Compile.Elixir.run([])
+      Mix.Tasks.Compile.App.run([])
+
+      properties = parse_resource_file(:custom_project)
+      assert properties[:env] == [exported: ~r/foo/E]
+    end)
+  end
+
   test ".app contains description and registered (as required by systools)" do
     in_fixture("no_mixfile", fn ->
       Mix.Project.push(MixTest.Case.Sample)

lib/mix/test/mix/tasks/compile.elixir_test.exs

@@ -1253,6 +1253,23 @@ defmodule Mix.Tasks.Compile.ElixirTest do
     end)
   end
 
+  test "recompiles with --force-elixir" do
+    in_fixture("no_mixfile", fn ->
+      Mix.Project.push(MixTest.Case.Sample)
+      assert Mix.Task.run("compile") == {:ok, []}
+      purge([A, B])
+
+      # Now we have a noop
+      Mix.Task.clear()
+      assert Mix.Task.run("compile") == {:noop, []}
+
+      # --force-elixir
+      Mix.Task.clear()
+      assert Mix.Task.run("compile", ["--verbose", "--force-elixir"]) == {:ok, []}
+      assert_received {:mix_shell, :info, ["Compiled lib/a.ex"]}
+    end)
+  end
+
   test "compiles files with autoload disabled" do
     in_fixture("no_mixfile", fn ->
       Mix.Project.push(MixTest.Case.Sample)

lib/mix/test/mix/tasks/help_test.exs

@@ -199,14 +199,23 @@ defmodule Mix.Tasks.HelpTest do
     in_tmp(context.test, fn ->
       output =
         capture_io(fn ->
-          Mix.Tasks.Help.run(["app:mix"])
+          Mix.Tasks.Help.run(["app:iex"])
         end)
 
-      assert output =~ "# Mix\n\nMix is a build tool"
+      assert output =~ "# IEx\n\nElixir's interactive shell."
+
+      if System.otp_release() >= "27" do
+        output =
+          capture_io(fn ->
+            Mix.Tasks.Help.run(["app:parsetools"])
+          end)
+
+        assert output =~ "# :leex"
+      end
     end)
   end
 
-  test "help unknown app:APP", context do
+  test "help app:UNKNOWN", context do
     in_tmp(context.test, fn ->
       Mix.Tasks.Help.run(["app:foobar"])
       assert_received {:mix_shell, :error, ["Application foobar does not exist or is not loaded"]}

lib/mix/test/test_helper.exs

@@ -43,12 +43,22 @@ cover_exclude =
     []
   end
 
+# OTP 28.1+
+re_import_exclude =
+  if Code.ensure_loaded?(:re) and function_exported?(:re, :import, 1) do
+    []
+  else
+    [:re_import]
+  end
+
 Code.require_file("../../elixir/scripts/cover_record.exs", __DIR__)
 CoverageRecorder.maybe_record("mix")
 
 ExUnit.start(
   trace: !!System.get_env("TRACE"),
-  exclude: epmd_exclude ++ os_exclude ++ git_exclude ++ line_exclude ++ cover_exclude,
+  exclude:
+    epmd_exclude ++
+      os_exclude ++ git_exclude ++ line_exclude ++ cover_exclude ++ re_import_exclude,
   include: line_include,
   assert_receive_timeout: String.to_integer(System.get_env("ELIXIR_ASSERT_TIMEOUT", "300"))
 )