Avoid flagging starred elements in C402 (#7466)

## Summary Rewriting these is not valid syntax. Part of #7455.
astral-sh · Sep 17, 2023 · 28273eb · 28273eb
1 parent 12acd19
commit 28273eb
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Showing 3 changed files with 26 additions and 13 deletions.
diff --git a/crates/ruff/resources/test/fixtures/flake8_comprehensions/C402.py b/crates/ruff/resources/test/fixtures/flake8_comprehensions/C402.py
@@ -19,3 +19,6 @@ def f(x):
 
 # Regression test for: https://github.com/astral-sh/ruff/issues/7086
 dict((k,v)for k,v in d.iteritems() if k in only_args)
+
+# Regression test for: https://github.com/astral-sh/ruff/issues/7455#issuecomment-1722458940
+dict((*v, k) for k, v in enumerate(calendar.month_abbr))
diff --git a/crates/ruff/src/rules/flake8_comprehensions/rules/unnecessary_generator_dict.rs b/crates/ruff/src/rules/flake8_comprehensions/rules/unnecessary_generator_dict.rs
@@ -54,18 +54,23 @@ pub(crate) fn unnecessary_generator_dict(
     else {
         return;
     };
-    if let Expr::GeneratorExp(ast::ExprGeneratorExp { elt, .. }) = argument {
-        match elt.as_ref() {
-            Expr::Tuple(ast::ExprTuple { elts, .. }) if elts.len() == 2 => {
-                let mut diagnostic = Diagnostic::new(UnnecessaryGeneratorDict, expr.range());
-                if checker.patch(diagnostic.kind.rule()) {
-                    diagnostic.try_set_fix(|| {
-                        fixes::fix_unnecessary_generator_dict(expr, checker).map(Fix::suggested)
-                    });
-                }
-                checker.diagnostics.push(diagnostic);
-            }
-            _ => {}
-        }
+    let Expr::GeneratorExp(ast::ExprGeneratorExp { elt, .. }) = argument else {
+        return;
+    };
+    let Expr::Tuple(ast::ExprTuple { elts, .. }) = elt.as_ref() else {
+        return;
+    };
+    if elts.len() != 2 {
+        return;
+    }
+    if elts.iter().any(Expr::is_starred_expr) {
+        return;
+    }
+    let mut diagnostic = Diagnostic::new(UnnecessaryGeneratorDict, expr.range());
+    if checker.patch(diagnostic.kind.rule()) {
+        diagnostic.try_set_fix(|| {
+            fixes::fix_unnecessary_generator_dict(expr, checker).map(Fix::suggested)
+        });
     }
+    checker.diagnostics.push(diagnostic);
 }
diff --git a/...ke8_comprehensions/snapshots/ruff__rules__flake8_comprehensions__tests__C402_C402.py.snap b/...ke8_comprehensions/snapshots/ruff__rules__flake8_comprehensions__tests__C402_C402.py.snap
@@ -251,6 +251,8 @@ C402.py:21:1: C402 [*] Unnecessary generator (rewrite as a `dict` comprehension)
 20 | # Regression test for: https://github.com/astral-sh/ruff/issues/7086
 21 | dict((k,v)for k,v in d.iteritems() if k in only_args)
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ C402
+22 | 
+23 | # Regression test for: https://github.com/astral-sh/ruff/issues/7455#issuecomment-1722458940
    |
    = help: Rewrite as a `dict` comprehension
 
@@ -260,5 +262,8 @@ C402.py:21:1: C402 [*] Unnecessary generator (rewrite as a `dict` comprehension)
 20 20 | # Regression test for: https://github.com/astral-sh/ruff/issues/7086
 21    |-dict((k,v)for k,v in d.iteritems() if k in only_args)
    21 |+{k: v for k,v in d.iteritems() if k in only_args}
+22 22 | 
+23 23 | # Regression test for: https://github.com/astral-sh/ruff/issues/7455#issuecomment-1722458940
+24 24 | dict((*v, k) for k, v in enumerate(calendar.month_abbr))