gh-117657: Fix data race in `dict_dict_merge` (gh-129755)

Found while running `test_load_attr_module` from `test_opcache` under TSan.

diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index 91cf013a1dc24ba4c3b39e2bb6122e884eefd27e..d979cd72b48e690f89ad7bb65cc391e16876a028 100644 (file)
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -3793,7 +3793,7 @@ dict_dict_merge(PyInterpreterState *interp, PyDictObject *mp, PyDictObject *othe
 
             ensure_shared_on_resize(mp);
             dictkeys_decref(interp, mp->ma_keys, IS_DICT_SHARED(mp));
-            mp->ma_keys = keys;
+            set_keys(mp, keys);
             STORE_USED(mp, other->ma_used);
             ASSERT_CONSISTENT(mp);