Support PEP 448 unpackings in dict calls.

2 files changed, 47 insertions, 11 deletions

diff --git a/astroid/brain/builtin_inference.py b/astroid/brain/builtin_inference.py
index 022a009..c6245be 100644
--- a/astroid/brain/builtin_inference.py
+++ b/astroid/brain/builtin_inference.py
@@ -7,6 +7,7 @@ from textwrap import dedent
 import six
 from astroid import (MANAGER, UseInferenceDefault, NotFoundError,
                      inference_tip, InferenceError, UnresolvableName)
+from astroid import arguments
 from astroid.builder import AstroidBuilder
 from astroid import helpers
 from astroid import nodes
@@ -229,25 +230,34 @@ def infer_dict(node, context=None):
 
     If a case can't be inferred, we'll fallback to default inference.
     """
-    if not node.args and not node.keywords:
+    call = arguments.CallSite.from_call(node)
+    if call.has_invalid_arguments() or call.has_invalid_keywords():
+        raise UseInferenceDefault
+
+    args = call.positional_arguments
+    kwargs = list(call.keyword_arguments.items())
+
+    if not args and not kwargs:
         # dict()
         return nodes.Dict()
-    elif node.keywords and not node.args:
+    elif kwargs and not args:
         # dict(a=1, b=2, c=4)
-        items = [(nodes.Const(arg.arg), arg.value) for arg in node.keywords]
-    elif len(node.args) == 1 and node.keywords:
+        items = [(nodes.Const(key), value) for key, value in kwargs]
+    elif len(args) == 1 and kwargs:
         # dict(some_iterable, b=2, c=4)
-        elts = _get_elts(node.args[0], context)
-        keys = [(nodes.Const(arg.arg), arg.value) for arg in node.keywords]
+        elts = _get_elts(args[0], context)
+        keys = [(nodes.Const(key), value) for key, value in kwargs]
         items = elts + keys
-    elif len(node.args) == 1:
-        items = _get_elts(node.args[0], context)
+    elif len(args) == 1:
+        items = _get_elts(args[0], context)
     else:
         raise UseInferenceDefault()
 
-    empty = nodes.Dict()
-    empty.items = items
-    return empty
+    value = nodes.Dict(col_offset=node.col_offset,
+                       lineno=node.lineno,
+                       parent=node.parent)
+    value.postinit(items)
+    return value
 
 
 def infer_super(node, context=None):
diff --git a/astroid/tests/unittest_inference.py b/astroid/tests/unittest_inference.py
index ed13fc2..9c80a92 100644
--- a/astroid/tests/unittest_inference.py
+++ b/astroid/tests/unittest_inference.py
@@ -1720,6 +1720,32 @@ class InferenceTest(resources.SysPathSetup, unittest.TestCase):
             self.assertIsInstance(inferred, Instance)
             self.assertEqual(inferred.qname(), "{}.dict".format(BUILTINS))
 
+    def test_dict_inference_kwargs(self):
+        ast_node = test_utils.extract_node('''dict(a=1, b=2, **{'c': 3})''')
+        self.assertInferDict(ast_node, {'a': 1, 'b': 2, 'c': 3})
+
+    @test_utils.require_version('3.5')
+    def test_dict_inference_for_multiple_starred(self):
+        pairs = [
+            ('dict(a=1, **{"b": 2}, **{"c":3})', {'a':1, 'b':2, 'c':3}),
+            ('dict(a=1, **{"b": 2}, d=4, **{"c":3})', {'a':1, 'b':2, 'c':3, 'd':4}),
+            ('dict({"a":1}, b=2, **{"c":3})', {'a':1, 'b':2, 'c':3}),
+        ]
+        for code, expected_value in pairs:
+            node = test_utils.extract_node(code)
+            self.assertInferDict(node, expected_value)
+
+    def test_dict_invalid_args(self):
+        invalid_values = [
+            'dict(*1)',
+            'dict(**lala)',
+            'dict(**[])',
+        ]
+        for invalid in invalid_values:
+            ast_node = test_utils.extract_node(invalid)
+            inferred = next(ast_node.infer())
+            self.assertIsInstance(inferred, Instance)
+            self.assertEqual(inferred.qname(), "{}.dict".format(BUILTINS))
 
     def test_str_methods(self):
         code = """