Expand C416 to dict comprehensions

adamchainz · Mar 17, 2023 · 7f1044f · 7f1044f
1 parent c95c753
commit 7f1044f
Show file tree

Hide file tree

Showing 3 changed files with 36 additions and 6 deletions.
diff --git a/README.rst b/README.rst
@@ -150,13 +150,14 @@ For example:
 * Rewrite ``sorted(iterable)[::-1]`` as ``sorted(iterable, reverse=True)``
 * Rewrite ``reversed(iterable[::-1])`` as ``iterable``
 
-C416: Unnecessary ``<list/set>`` comprehension - rewrite using ``<list/set>``\().
+C416: Unnecessary ``<dict/list/set>`` comprehension - rewrite using ``<dict/list/set>``\().
 ---------------------------------------------------------------------------------
 
 It's unnecessary to use a list comprehension if the elements are unchanged.
-The iterable should be wrapped in ``list()`` or ``set()`` instead.
+The iterable should be wrapped in ``dict()``, ``list()``, or ``set()`` instead.
 For example:
 
+* Rewrite ``{a:b for a, b in iterable}`` as ``dict(iterable)``
 * Rewrite ``[x for x in iterable]`` as ``list(iterable)``
 * Rewrite ``{x for x in iterable}`` as ``set(iterable)``
 

diff --git a/src/flake8_comprehensions/__init__.py b/src/flake8_comprehensions/__init__.py
@@ -295,15 +295,30 @@ def run(self) -> Generator[tuple[int, int, str, type[Any]], None, None]:
                             type(self),
                         )
 
-            elif isinstance(node, (ast.ListComp, ast.SetComp)):
+            elif isinstance(node, (ast.DictComp, ast.ListComp, ast.SetComp)):
                 if (
                     len(node.generators) == 1
                     and not node.generators[0].ifs
                     and not node.generators[0].is_async
                     and (
-                        isinstance(node.elt, ast.Name)
-                        and isinstance(node.generators[0].target, ast.Name)
-                        and node.elt.id == node.generators[0].target.id
+                        (
+                            isinstance(node, (ast.ListComp, ast.SetComp))
+                            and isinstance(node.elt, ast.Name)
+                            and isinstance(node.generators[0].target, ast.Name)
+                            and node.elt.id == node.generators[0].target.id
+                        )
+                        or (
+                            isinstance(node, ast.DictComp)
+                            and isinstance(node.key, ast.Name)
+                            and isinstance(node.value, ast.Name)
+                            and isinstance(node.generators[0].target, ast.Tuple)
+                            and tuple(
+                                x.id
+                                for x in node.generators[0].target.elts
+                                if isinstance(x, ast.Name)
+                            )
+                            == (node.key.id, node.value.id)
+                        )
                     )
                 ):
                     yield (

diff --git a/tests/test_flake8_comprehensions.py b/tests/test_flake8_comprehensions.py
@@ -810,6 +810,20 @@ def test_C416_pass(code, flake8_path):
                 + "rewrite using set().",
             ],
         ),
+        (
+            "{x: y for x, y in zip(range(5), range(5))}",
+            [
+                "./example.py:1:1: C416 Unnecessary dict comprehension - "
+                + "rewrite using dict().",
+            ],
+        ),
+        (
+            "{x: y for (x, y) in zip(range(5), range(5))}",
+            [
+                "./example.py:1:1: C416 Unnecessary dict comprehension - "
+                + "rewrite using dict().",
+            ],
+        ),
     ],
 )
 def test_C416_fail(code, failures, flake8_path):