Change error message for incompatible type assignment when using Generics

mypy/checkexpr.py

@@ -1511,14 +1511,16 @@ def check_argument_types(self,
         mapper = ArgTypeExpander(self.argument_infer_context())
         for i, actuals in enumerate(formal_to_actual):
             for actual in actuals:
+
                 actual_type = arg_types[actual]
                 if actual_type is None:
                     continue  # Some kind of error was already reported.
                 actual_kind = arg_kinds[actual]
                 # Check that a *arg is valid as varargs.
                 if (actual_kind == nodes.ARG_STAR and
-                        not self.is_valid_var_arg(actual_type)):
+                    not self.is_valid_var_arg(actual_type)):
                     messages.invalid_var_arg(actual_type, context)
+
                 if (actual_kind == nodes.ARG_STAR2 and
                         not self.is_valid_keyword_var_arg(actual_type)):
                     is_mapping = is_subtype(actual_type, self.chk.named_type('typing.Mapping'))

mypy/messages.py

@@ -580,9 +580,9 @@ def incompatible_argument(self,
                     outer_context.index.value, quote_type_string(arg_type_str),
                     quote_type_string(expected_type_str))
             else:
-                msg = 'Argument {} {}has incompatible type {}; expected {}'.format(
-                    arg_label, target, quote_type_string(arg_type_str),
-                    quote_type_string(expected_type_str))
+                msg = 'expression has type {}， variable has type {}'.format(
+                    quote_type_string(arg_type_str), quote_type_string(expected_type_str))
+
             object_type = get_proper_type(object_type)
             if isinstance(object_type, TypedDictType):
                 code = codes.TYPEDDICT_ITEM

test-data/unit/check-varargs.test

@@ -545,11 +545,10 @@ if int():
     b, b = f(b, b, *aa) # E: Argument 3 to "f" has incompatible type "*List[A]"; expected "B"
 if int():
     a, b = f(a, *a)  # E: List or tuple expected as variable arguments
-if int():
-    a, b = f(*a)     # E: List or tuple expected as variable arguments
-
 if int():
     a, a = f(*aa)
+if int():
+     a, b = f(*a)     # E: List or tuple expected as variable arguments
 if int():
     b, a = f(b, *aa)
 if int():