Suppress useless-super-delegation if return type changed (#5822) (#…

…6141)

* Reinstate warning if base method has no return type annotation

pylint/checkers/classes/class_checker.py

@@ -1277,6 +1277,14 @@ def form_annotations(arguments):
                 if called_annotations != overridden_annotations:
                     return
 
+            if (
+                function.returns is not None
+                and meth_node.returns is not None
+                and meth_node.returns.as_string() != function.returns.as_string()
+            ):
+                # Override adds typing information to the return type
+                return
+
         if _definition_equivalent_to_call(params, args):
             self.add_message(
                 "useless-super-delegation", node=function, args=(function.name,)

tests/functional/u/useless/useless_super_delegation_py35.py

@@ -10,3 +10,37 @@ class UselessSuper(object):
 
     def useless(self, first, *, second=None, **kwargs): # [useless-super-delegation]
         return super().useless(first, second=second, **kwargs)
+
+# pylint: disable=wrong-import-position
+import random
+from typing import Any
+
+class ReturnTypeAny:
+    choices = ['a', 1, (2, 3)]
+
+    def draw(self) -> Any:
+        return random.choice(self.choices)
+
+class ReturnTypeNarrowed(ReturnTypeAny):
+    choices = [1, 2, 3]
+
+    def draw(self) -> int:
+        return super().draw()
+
+class NoReturnType:
+    choices = ['a', 1, (2, 3)]
+
+    def draw(self):
+        return random.choice(self.choices)
+
+class ReturnTypeSpecified(NoReturnType):
+    choices = ['a', 'b']
+
+    def draw(self) -> str: # [useless-super-delegation]
+        return super().draw()
+
+class ReturnTypeSame(ReturnTypeAny):
+    choices = ['a', 'b']
+
+    def draw(self) -> Any: # [useless-super-delegation]
+        return super().draw()

tests/functional/u/useless/useless_super_delegation_py35.txt

@@ -1 +1,3 @@
 useless-super-delegation:11:4:11:15:UselessSuper.useless:Useless super delegation in method 'useless':UNDEFINED
+useless-super-delegation:39:4:39:12:ReturnTypeSpecified.draw:Useless super delegation in method 'draw':UNDEFINED
+useless-super-delegation:45:4:45:12:ReturnTypeSame.draw:Useless super delegation in method 'draw':UNDEFINED