From 6531343242e28b179e6d3d25af3b7fb65c90b66b Mon Sep 17 00:00:00 2001
From: Andrii Furmanets <furmanets.andriy@gmail.com>
Date: Wed, 4 Mar 2026 16:41:27 +0200
Subject: weakmap: return assigned value from #[]= and add regression test

---
 test/ruby/test_weakmap.rb | 7 +++++++
 weakmap.c                 | 2 +-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/test/ruby/test_weakmap.rb b/test/ruby/test_weakmap.rb
index 4f5823ecf4..2f5c747339 100644
--- a/test/ruby/test_weakmap.rb
+++ b/test/ruby/test_weakmap.rb
@@ -39,6 +39,13 @@ class TestWeakMap < Test::Unit::TestCase
     assert_same(:foo, @wm[x])
   end
 
+  def test_aset_returns_value
+    key = Object.new
+    value = Object.new
+
+    assert_same(value, @wm.send(:[]=, key, value))
+  end
+
   def assert_weak_include(m, k, n = 100)
     if n > 0
       return assert_weak_include(m, k, n-1)
diff --git a/weakmap.c b/weakmap.c
index 80ef29b4cc..7cef1fd46a 100644
--- a/weakmap.c
+++ b/weakmap.c
@@ -394,7 +394,7 @@ wmap_aset(VALUE self, VALUE key, VALUE val)
     RB_OBJ_WRITTEN(self, Qundef, key);
     RB_OBJ_WRITTEN(self, Qundef, val);
 
-    return Qnil;
+    return val;
 }
 
 /* Retrieves a weakly referenced object with the given key */
-- 
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