From 0114184659d330ee5550af94293de85690bcd196 Mon Sep 17 00:00:00 2001
From: sabiwara <sabiwara@proton.me>
Date: Sun, 8 Mar 2026 14:18:27 +0900
Subject: [PATCH] Warn when defining @type record(), fixes CI on OTP29

---
 lib/elixir/lib/kernel/typespec.ex        | 17 ++++++++++++++---
 lib/elixir/test/elixir/typespec_test.exs | 20 +++++++++++---------
 2 files changed, 25 insertions(+), 12 deletions(-)

diff --git a/lib/elixir/lib/kernel/typespec.ex b/lib/elixir/lib/kernel/typespec.ex
index 1f3539bcf93..f37a5c30590 100644
--- a/lib/elixir/lib/kernel/typespec.ex
+++ b/lib/elixir/lib/kernel/typespec.ex
@@ -255,9 +255,20 @@ defmodule Kernel.Typespec do
 
       case type_to_signature(expr) do
         {name, arity} = type_pair ->
-          if built_in_type?(name, arity) do
-            message = "type #{name}/#{arity} is a built-in type and it cannot be redefined"
-            compile_error(env, message)
+          cond do
+            # This is a built-in type since OTP 29 but it just generates a warning for now
+            {name, arity} == {:record, 0} ->
+              IO.warn("type #{name}/#{arity} is overriding a built-in type",
+                file: file,
+                line: line
+              )
+
+            built_in_type?(name, arity) ->
+              message = "type #{name}/#{arity} is a built-in type and it cannot be redefined"
+              compile_error(env, message)
+
+            true ->
+              :ok
           end
 
           if Map.has_key?(type_pairs, type_pair) do
diff --git a/lib/elixir/test/elixir/typespec_test.exs b/lib/elixir/test/elixir/typespec_test.exs
index ab24ce5e115..2643c1d4392 100644
--- a/lib/elixir/test/elixir/typespec_test.exs
+++ b/lib/elixir/test/elixir/typespec_test.exs
@@ -681,15 +681,17 @@ defmodule TypespecTest do
       end
     end
 
-    test "@type can be named record" do
-      bytecode =
-        test_module do
-          @type record :: binary
-          @spec foo?(record) :: boolean
-          def foo?(_), do: true
-        end
-
-      assert [type: {:record, {:type, _, :binary, []}, []}] = types(bytecode)
+    test "@type named record/0 warns" do
+      assert ExUnit.CaptureIO.capture_io(:stderr, fn ->
+               bytecode =
+                 test_module do
+                   @type record :: binary
+                   @spec foo?(record) :: boolean
+                   def foo?(_), do: true
+                 end
+
+               assert [type: {:record, {:type, _, :binary, []}, []}] = types(bytecode)
+             end) =~ "type record/0 is overriding a built-in type"
     end
 
     test "@type with an invalid map notation" do