Always allow returning Any from lambda (python#15413)

ilevkivskyi · web-flow · commit 9e7bc383eb9a · 2023-06-11T13:08:12.000-07:00
diff --git a/mypy/checker.py b/mypy/checker.py
@@ -4270,6 +4270,7 @@ def check_return_stmt(self, s: ReturnStmt) -> None:
                             isinstance(return_type, Instance)
                             and return_type.type.fullname == "builtins.object"
                         )
+                        and not is_lambda
                     ):
                         self.msg.incorrectly_returning_any(return_type, s)
                     return
diff --git a/test-data/unit/check-flags.test b/test-data/unit/check-flags.test
@@ -2184,3 +2184,14 @@ def f(x: bytes, y: bytearray, z: memoryview) -> None:
 follow_imports = skip
 follow_imports_for_stubs = true
 [builtins fixtures/dict.pyi]
+
+[case testReturnAnyLambda]
+# flags: --warn-return-any
+from typing import Any, Callable
+
+def cb(f: Callable[[int], int]) -> None: ...
+a: Any
+cb(lambda x: a)  # OK
+
+fn = lambda x: a
+cb(fn)

Original file line number	Diff line number	Diff line change
`@@ -4270,6 +4270,7 @@ def check_return_stmt(self, s: ReturnStmt) -> None:`
`4270`	`4270`	`isinstance(return_type, Instance)`
`4271`	`4271`	`and return_type.type.fullname == "builtins.object"`
`4272`	`4272`	`)`
	`4273`	`+ and not is_lambda`
`4273`	`4274`	`):`
`4274`	`4275`	`self.msg.incorrectly_returning_any(return_type, s)`
`4275`	`4276`	`return`