Suggest typing.Callable when using callable as type (#12204)

Author: siiptuo

mypy/typeanal.py

@@ -494,6 +494,8 @@ def analyze_unbound_type_without_type_info(self, t: UnboundType, sym: SymbolTabl
             message = 'Function "{}" is not valid as a type'
             if name == 'builtins.any':
                 notes.append('Perhaps you meant "typing.Any" instead of "any"?')
+            elif name == 'builtins.callable':
+                notes.append('Perhaps you meant "typing.Callable" instead of "callable"?')
             else:
                 notes.append('Perhaps you need "Callable[...]" or a callback protocol?')
         elif isinstance(sym.node, MypyFile):

test-data/unit/check-functions.test

@@ -2610,3 +2610,8 @@ reveal_type(foo()) # N: Revealed type is "None"
 def a(b: any): pass # E: Function "builtins.any" is not valid as a type \
                     # N: Perhaps you meant "typing.Any" instead of "any"?
 [builtins fixtures/any.pyi]
+
+[case testCallableArgument]
+def a(b: callable): pass # E: Function "builtins.callable" is not valid as a type \
+                         # N: Perhaps you meant "typing.Callable" instead of "callable"?
+[builtins fixtures/callable.pyi]