From 66c2ba068b8a7f64e853d3f9a347c4bf0a855e05 Mon Sep 17 00:00:00 2001
From: Ran Benita <ran@unusedvar.com>
Date: Fri, 31 Jul 2020 11:30:52 +0300
Subject: [PATCH] Fix untyped decorator overload error on class decorator with
 __call__ overloads

---
 mypy/checker.py                       |  5 ++++-
 test-data/unit/check-overloading.test | 27 +++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/mypy/checker.py b/mypy/checker.py
index 2558440168e3..75739fe87a00 100644
--- a/mypy/checker.py
+++ b/mypy/checker.py
@@ -5757,7 +5757,10 @@ def is_untyped_decorator(typ: Optional[Type]) -> bool:
     elif isinstance(typ, Instance):
         method = typ.type.get_method('__call__')
         if method:
-            return not is_typed_callable(method.type)
+            if isinstance(method.type, Overloaded):
+                return any(is_untyped_decorator(item) for item in method.type.items())
+            else:
+                return not is_typed_callable(method.type)
         else:
             return False
     elif isinstance(typ, Overloaded):
diff --git a/test-data/unit/check-overloading.test b/test-data/unit/check-overloading.test
index 4b3fbfdda851..959983db4495 100644
--- a/test-data/unit/check-overloading.test
+++ b/test-data/unit/check-overloading.test
@@ -4955,6 +4955,33 @@ def g(name: str) -> int:
 reveal_type(f)  # N: Revealed type is 'def (name: builtins.str) -> builtins.int'
 reveal_type(g)  # N: Revealed type is 'def (name: builtins.str) -> builtins.int'
 
+[case testDisallowUntypedDecoratorsOverloadDunderCall]
+# flags: --disallow-untyped-decorators
+from typing import Any, Callable, overload, TypeVar
+
+F = TypeVar('F', bound=Callable[..., Any])
+
+class Dec:
+    @overload
+    def __call__(self, x: F) -> F: ...
+    @overload
+    def __call__(self, x: str) -> Callable[[F], F]: ...
+    def __call__(self, x) -> Any:
+        pass
+
+dec = Dec()
+
+@dec
+def f(name: str) -> int:
+    return 0
+
+@dec('abc')
+def g(name: str) -> int:
+    return 0
+
+reveal_type(f)  # N: Revealed type is 'def (name: builtins.str) -> builtins.int'
+reveal_type(g)  # N: Revealed type is 'def (name: builtins.str) -> builtins.int'
+
 [case testOverloadBadArgumentsInferredToAny1]
 from typing import Union, Any, overload