Set type of keyword arguments to Dict[unicode, Any] in Python 2.

This fixes #1954

Author: Roy Williams

mypy/checker.py

@@ -554,8 +554,9 @@ def is_implicit_any(t: Type) -> bool:
                                                            [arg_type])
                     elif typ.arg_kinds[i] == nodes.ARG_STAR2:
                         arg_type = self.named_generic_type('builtins.dict',
-                                                           [self.str_type(),
+                                                           [self.unicode_type(),
                                                             arg_type])
+
                     item.arguments[i].variable.type = arg_type
 
                 # Type check initialization expressions.
@@ -2115,6 +2116,13 @@ def str_type(self) -> Instance:
         """Return instance type 'str'."""
         return self.named_type('builtins.str')
 
+    def unicode_type(self) -> Instance:
+        """Return instance type 'unicode'."""
+        if self.options.python_version[0] >= 3:
+            return self.named_type('builtins.str')
+        else:
+            return self.named_type('builtins.unicode')
+
     def check_type_equivalency(self, t1: Type, t2: Type, node: Context,
                                msg: str = messages.INCOMPATIBLE_TYPES) -> None:
         """Generate an error if the types are not equivalent. The

test-data/unit/python2eval.test

@@ -128,6 +128,25 @@ print '>', ['a', b'b', u'c']
 [out]
 > [u'a', 'b', u'c']
 
+[case testUnicodeLiteralsReadKwargs_python2]
+from __future__ import unicode_literals
+def f(**kwargs):  # type: (...) -> None
+  return kwargs.get('a', '')
+f(a='b')
+[out]
+
+[case testUnicodeStrReadKwargs_python2]
+def f(**kwargs):  # type: (...) -> None
+  return kwargs.get(u'a', '')
+f(a='b')
+[out]
+
+[case testPy2StrReadKwargs_python2]
+def f(**kwargs):  # type: (...) -> None
+  return kwargs.get('a', '')
+f(a='b')
+[out]
+
 [case testUnicodeLiteralsKwargs_python2]
 from __future__ import unicode_literals
 def f(**kwargs):  # type: (...) -> None