Fix C402/C404 false positive for dict() with kwargs (#458)

Author: adamchainz

HISTORY.rst

@@ -2,6 +2,10 @@
 History
 =======
 
+* Fix false positive in rules C402 and C404 for ``dict()`` calls with keyword arguments.
+
+  Thanks to Anders Kaseorg for the report in `Issue #457 <https://github.com/adamchainz/flake8-comprehensions/issues/457>`__.
+
 3.10.0 (2022-05-19)
 -------------------
 

src/flake8_comprehensions/__init__.py

@@ -68,10 +68,11 @@ def run(self) -> Generator[tuple[int, int, str, type[Any]], None, None]:
 
                 elif (
                     num_positional_args == 1
+                    and node.func.id == "dict"
+                    and len(node.keywords) == 0
                     and isinstance(node.args[0], (ast.GeneratorExp, ast.ListComp))
                     and isinstance(node.args[0].elt, ast.Tuple)
                     and len(node.args[0].elt.elts) == 2
-                    and node.func.id == "dict"
                 ):
                     if isinstance(node.args[0], ast.GeneratorExp):
                         msg = "C402"

tests/test_flake8_comprehensions.py

@@ -129,6 +129,8 @@ def test_C401_fail(code, failures, flake8_path):
         foo = [('a', 1), ('b', 2), ('c', 3)]
         dict(pair for pair in foo if pair[1] % 2 == 0)
         """,
+        # Previously a false positive:
+        "dict(((x, str(x)) for x in range(10)), c=1)",
     ],
 )
 def test_C402_pass(code, flake8_path):
@@ -204,6 +206,8 @@ def test_C403_fail(code, failures, flake8_path):
         "foo = {x: x for x in range(10)}",
         # Previously a false positive:
         "foo = dict([x.split('=') for x in ['a=1', 'b=2']])",
+        # Previously a false positive:
+        "dict([(x, x) for x in range(10)], y=2)",
     ],
 )
 def test_C404_pass(code, flake8_path):