Merge branch 'master' of https://github.com/python/mypy into HEAD

# Conflicts:
#	mypy/checkexpr.py

mypy/checkexpr.py

@@ -68,7 +68,7 @@
 from mypy.typeops import (
     tuple_fallback, make_simplified_union, true_only, false_only, erase_to_union_or_bound,
     function_type, callable_type, try_getting_str_literals, custom_special_method,
-    is_literal_type_like, try_getting_str_literals_from_type,
+    is_literal_type_like, try_expanding_sum_type_to_union, try_getting_str_literals_from_type
 )
 from mypy.message_registry import ErrorMessage
 import mypy.errorcodes as codes
@@ -4027,38 +4027,24 @@ def is_valid_var_arg(self, typ: Type) -> bool:
 
     def is_valid_keyword_var_arg(self, typ: Type) -> bool:
         """Is a type valid as a **kwargs argument?"""
-        mapping_type = self.chk.named_generic_type('typing.Mapping',
-                    [self.named_type('builtins.str'),
-                     AnyType(TypeOfAny.special_form)])
+                mapping_type = self.chk.named_generic_type(
+                'typing.Mapping', [self.named_type('builtins.str'), AnyType(TypeOfAny.special_form)])
         typ = get_proper_type(typ)
 
-        if self.chk.options.python_version[0] >= 3:
-            return (
-                (is_subtype(typ, mapping_type))
-                or
-                (isinstance(typ, Instance) and
-                 is_subtype(typ, self.chk.named_type('typing.Mapping')) and
-                 (try_getting_str_literals_from_type(
-                     map_instance_to_supertype(typ,
-                                               mapping_type.type).args[0]) is not None)))
-
-        else:
-            return (
-                (is_subtype(typ, self.chk.named_generic_type(
-                    'typing.Mapping',
-                    [self.named_type('builtins.str'),
-                     AnyType(TypeOfAny.special_form)])))
-                or
-                (is_subtype(typ, self.chk.named_generic_type(
-                    'typing.Mapping',
-                    [self.named_type('builtins.unicode'),
-                     AnyType(TypeOfAny.special_form)])))
-                or
-                (isinstance(typ, Instance) and
-                 is_subtype(typ, self.chk.named_type('typing.Mapping')) and
-                 try_getting_str_literals_from_type(
-                     map_instance_to_supertype(typ,
-                                               mapping_type.type).args[0]) is not None))
+        ret = (
+     is_subtype(typ, mapping_type)      or
+            (isinstance(typ, Instance)              and
+                 is_subtype(typ, self.chk.named_generic_type('typing.Mapping',
+                    [UninhabitedType(), UninhabitedType()]))              and
+                try_getting_str_literals_from_type(map_instance_to_supertype(
+                    typ, mapping_type.type).arg[0]) is not None
+ )              or
+            isinstance(typ, ParamSpecType)
+        )
+        if self.chk.options.python_version[0] < 3:
+            ret = ret or is_subtype(typ, self.chk.named_generic_type('typing.Mapping',
+                [self.named_type('builtins.unicode'), AnyType(TypeOfAny.special_form)]))
+        return ret
 
     def has_member(self, typ: Type, member: str) -> bool:
         """Does type have member with the given name?"""