From a6844bf72533cda1fa1704aefc4ece63e7bbc641 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jos=C3=A9=20Valim?= <jose.valim@dashbit.co>
Date: Thu, 10 Jul 2025 17:30:36 +0200
Subject: [PATCH] Add tests for allow_locals option

---
 lib/elixir/lib/macro/env.ex               |  8 ++++----
 lib/elixir/src/elixir_dispatch.erl        |  4 +---
 lib/elixir/test/elixir/macro/env_test.exs | 19 +++++++++++++++++++
 3 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/lib/elixir/lib/macro/env.ex b/lib/elixir/lib/macro/env.ex
index edae8a4cc5..af8d79b779 100644
--- a/lib/elixir/lib/macro/env.ex
+++ b/lib/elixir/lib/macro/env.ex
@@ -558,13 +558,13 @@ defmodule Macro.Env do
 
     * `:allow_locals` - controls how local macros are resolved.
       Defaults to `true`.
-      
+
       - When `false`, does not attempt to capture local macros defined in the
         current module in `env`
       - When `true`, uses a default resolver that looks for public macros in
         the current module
-      - When a function, uses the function as a custom local resolver. The function
-        must have the signature: `(meta, name, arity, env) -> function() | false`
+      - When a function, it will be invoked to lazily compute a local function
+        (or return false). It has signature `(-> function() | false)`
 
     * `:check_deprecations` - when set to `false`, does not check for deprecations
       when expanding macros
@@ -591,7 +591,7 @@ defmodule Macro.Env do
         # When allow_locals is a callback, we don't need to pass module macros as extra
         # because the callback will handle local macro resolution
         extra =
-          if is_function(allow_locals, 4) do
+          if is_function(allow_locals, 0) do
             []
           else
             case allow_locals and function_exported?(module, :__info__, 1) do
diff --git a/lib/elixir/src/elixir_dispatch.erl b/lib/elixir/src/elixir_dispatch.erl
index ea52a61df9..346097e9a7 100644
--- a/lib/elixir/src/elixir_dispatch.erl
+++ b/lib/elixir/src/elixir_dispatch.erl
@@ -175,9 +175,7 @@ expand_import(Meta, Name, Arity, E, Extra, AllowLocals, Trace) ->
       Local = case AllowLocals of
         false -> false;
         true  -> elixir_def:local_for(Meta, Name, Arity, [defmacro, defmacrop], E);
-        Fun when is_function(Fun, 4) ->
-          %% If we have a custom local resolver, use it.
-          Fun(Meta, Name, Arity, E)
+        Fun when is_function(Fun, 0) -> Fun()
       end,
 
       case Dispatch of
diff --git a/lib/elixir/test/elixir/macro/env_test.exs b/lib/elixir/test/elixir/macro/env_test.exs
index 3138f54251..07e6a5b954 100644
--- a/lib/elixir/test/elixir/macro/env_test.exs
+++ b/lib/elixir/test/elixir/macro/env_test.exs
@@ -207,6 +207,25 @@ defmodule Macro.EnvTest do
       assert fun.([generated: true], [quote(do: hello())]) == quote(generated: true, do: hello())
     end
 
+    defmacro allow_locals_example, do: :ok
+
+    test "allow_locals" do
+      {:macro, Macro.EnvTest, fun} =
+        expand_import(env(), meta(), :allow_locals_example, 0)
+
+      assert fun.([], []) == :ok
+
+      assert expand_import(env(), meta(), :allow_locals_example, 0, allow_locals: false) ==
+               {:error, :not_found}
+
+      assert expand_import(env(), meta(), :allow_locals_example, 0,
+               allow_locals: fn -> send(self(), false) end
+             ) ==
+               {:error, :not_found}
+
+      assert_received false
+    end
+
     test "with tracing and deprecations" do
       message = "MacroEnvMacros.my_deprecated_macro/1 is deprecated"