Merge branch 'eigengrau-disambiguate-if-needed'

Author: JukkaL

mypy/messages.py

@@ -417,8 +417,14 @@ def incompatible_argument(self, n: int, m: int, callee: CallableType, arg_type:
                 expected_type = callee.arg_types[m - 1]
             except IndexError:  # Varargs callees
                 expected_type = callee.arg_types[-1]
+            arg_type_str = self.format(arg_type)
+            expected_type_str = self.format(expected_type)
+            # If type names turn out ambiguous, attempt to disambiguate.
+            if arg_type_str == expected_type_str:
+                arg_type_str = self.format(arg_type, verbose=True)
+                expected_type_str = self.format(expected_type, verbose=True)
             msg = 'Argument {} {}has incompatible type {}; expected {}'.format(
-                n, target, self.format(arg_type), self.format(expected_type))
+                n, target, arg_type_str, expected_type_str)
         self.fail(msg, context)
 
     def invalid_index_type(self, index_type: Type, base_str: str,

mypy/test/data/check-classes.test

@@ -1228,6 +1228,12 @@ class B:
 [out]
 main: note: In member "f" of class "B":
 
+[case testClassVsInstanceDisambiguation]
+class A: pass
+def f(x: A) -> None: pass
+f(A) # E: Argument 1 to "f" has incompatible type "A" (type object); expected "A"
+[out]
+
 -- TODO
 --   attribute inherited from superclass; assign in __init__
 --   refer to attribute before type has been inferred (the initialization in