Narrow for frozendict membership check (#21709)

hauntsaninja · web-flow · commit cbcb51add309 · 2026-07-08T23:55:18.000-07:00
diff --git a/mypy/checker.py b/mypy/checker.py
@@ -8892,6 +8892,7 @@ def builtin_item_type(tp: Type) -> Type | None:
             "builtins.list",
             "builtins.tuple",
             "builtins.dict",
+            "builtins.frozendict",
             "builtins.set",
             "builtins.frozenset",
             "_collections_abc.dict_keys",
