When positional args passed to dict(), analyze them. Fix #1357. (#1359)

Author: gvanrossum

mypy/semanal.py

@@ -1811,6 +1811,9 @@ def translate_dict_call(self, call: CallExpr) -> Optional[DictExpr]:
         if not call.args:
             return None
         if not all(kind == ARG_NAMED for kind in call.arg_kinds):
+            # Must still accept those args.
+            for a in call.args:
+                a.accept(self)
             return None
         expr = DictExpr([(StrExpr(key), value)
                          for key, value in zip(call.arg_names, call.args)])

mypy/test/data/check-expressions.test

@@ -1376,3 +1376,9 @@ d4 = dict(a=1, b=1)
 d4.xyz # E: Dict[str, int] has no attribute "xyz"
 d5 = dict(a=1, b='') # type: Dict[str, Any]
 [builtins fixtures/dict.py]
+
+[case testDictWithoutKeywordArgs]
+dict(undefined)
+[builtins fixtures/dict.py]
+[out]
+main:1: error: Name 'undefined' is not defined

mypy/test/data/fixtures/dict.py

@@ -1,6 +1,6 @@
 # Builtins stub used in dictionary-related test cases.
 
-from typing import TypeVar, Generic, Iterable, Iterator
+from typing import TypeVar, Generic, Iterable, Iterator, Any
 
 T = TypeVar('T')
 S = TypeVar('S')
@@ -11,6 +11,7 @@ def __init__(self) -> None: pass
 class type: pass
 
 class dict(Generic[T, S]):
+    def __init__(self, arg: Any = None) -> None: pass
     def __setitem__(self, k: T, v: S) -> None: pass
     def update(self, a: 'dict[T, S]') -> None: pass
 class int: pass # for convenience