Fix C406 false positives (#491)

Author: adamchainz

CHANGELOG.rst

@@ -2,6 +2,10 @@
 Changelog
 =========
 
+* Fix false positives in C406 “unnecessary dict literal”.
+
+  Fixes `Issue #260 <https://github.com/adamchainz/flake8-comprehensions/issues/260>`__.
+
 3.11.0 (2023-03-18)
 -------------------
 

src/flake8_comprehensions/__init__.py

@@ -120,7 +120,16 @@ def run(self) -> Generator[tuple[int, int, str, type[Any]], None, None]:
                 elif (
                     num_positional_args == 1
                     and isinstance(node.args[0], (ast.Tuple, ast.List))
-                    and node.func.id in ("tuple", "list", "set", "dict")
+                    and (
+                        node.func.id in ("tuple", "list", "set")
+                        or (
+                            node.func.id == "dict"
+                            and all(
+                                isinstance(i, ast.Tuple) and len(i.elts) == 2
+                                for i in node.args[0].elts
+                            )
+                        )
+                    )
                 ):
                     suffix = "rewrite as a {func} literal."
                     msg_key = {

tests/test_flake8_comprehensions.py

@@ -289,6 +289,8 @@ def test_C405_fail(code, failures, flake8_path):
     "code",
     [
         "foo = dict(range)",
+        "something = (1, 2); dict([something])",
+        "dict([(1,)])",
     ],
 )
 def test_C406_pass(code, flake8_path):