Ignore decorated functions and classes

pyflakes/checker.py

@@ -1845,9 +1845,15 @@ def checkUnusedBindings():
                 for name, binding in self.scope.unusedBindings():
                     if isinstance(binding, Assignment):
                         self.report(messages.UnusedVariable, binding.source, name)
-                    elif isinstance(binding, ClassDefinition):
+                    elif (
+                        isinstance(binding, ClassDefinition)
+                        and not binding.source.decorator_list
+                    ):
                         self.report(messages.UnusedClass, binding.source, name)
-                    elif isinstance(binding, FunctionDefinition):
+                    elif (
+                        isinstance(binding, FunctionDefinition)
+                        and not binding.source.decorator_list
+                    ):
                         self.report(messages.UnusedFunction, binding.source, name)
             self.deferAssignment(checkUnusedBindings)
 

pyflakes/test/test_other.py

@@ -1793,6 +1793,20 @@ def _():
                 pass
         ''')
 
+    def test_usedDecoratedFunction(self):
+        """
+        Don't warn when the function is decorated because decorators can do
+        anything, like copy it into global state.
+        """
+        self.flakes('''
+        from somewhere import decorator
+
+        def a():
+            @decorator
+            def b():
+                pass
+        ''')
+
 
 class TestUnusedClass(TestCase):
     """
@@ -1820,6 +1834,20 @@ class _:
                 pass
         ''')
 
+    def test_usedDecoratedClass(self):
+        """
+        Don't warn when the class is decorated because decorators can do
+        anything, like copy it into global state.
+        """
+        self.flakes('''
+        from somewhere import decorator
+
+        def a():
+            @decorator
+            class B:
+                pass
+        ''')
+
 
 class TestStringFormatting(TestCase):