Fix #11483: Incorrect type inference from context manager __exit__ return type with Generic

packages/pyright-internal/src/tests/samples/with7.py

@@ -36,3 +36,25 @@ def test_multi_typevar_context_manager() -> None:
         reveal_type(ctx, expected_text="int")
         bar = 1
     reveal_type(bar, expected_text="Literal['str', 1]")
+
+
+class AsyncContextManager(Generic[T]):
+    async def __aenter__(self) -> Self: ...
+
+    async def __aexit__(self, exc_type, exc_val, exc_tb) -> T: ...
+
+
+async def test_generic_async_context_manager() -> None:
+    # __aexit__ specializes to bool, so the exception may have been suppressed
+    # and the body may not have run.
+    baz = "str"
+    async with AsyncContextManager[bool]() as ctx:
+        baz = 1
+    reveal_type(baz, expected_text="Literal['str', 1]")
+
+    # __aexit__ specializes to None, so the exception is never suppressed and
+    # the entire body must have run.
+    qux = "str"
+    async with AsyncContextManager[None]() as ctx:
+        qux = 1
+    reveal_type(qux, expected_text="Literal[1]")