add generator/compehrension expressions

crates/ruff_linter/resources/test/fixtures/pylint/unnecessary_list_index_lookup.py

@@ -2,6 +2,10 @@
 
 
 def fix_these():
+    [letters[index] for index, letter in enumerate(letters)]  # PLR1736
+    {letters[index] for index, letter in enumerate(letters)}  # PLR1736
+    {letter: letters[index] for index, letter in enumerate(letters)}  # PLR1736
+
     for index, letter in enumerate(letters):
         print(letters[index])  # PLR1736
         blah = letters[index]  # PLR1736
@@ -16,6 +20,10 @@ def dont_fix_these():
 
 
 def value_intentionally_unused():
+    [letters[index] for index, _ in enumerate(letters)]  # PLR1736
+    {letters[index] for index, _ in enumerate(letters)}  # PLR1736
+    {index: letters[index] for index, _ in enumerate(letters)}  # PLR1736
+
     for index, _ in enumerate(letters):
         print(letters[index])  # Ok
         blah = letters[index]  # Ok

crates/ruff_linter/src/checkers/ast/analyze/expression.rs

@@ -1295,6 +1295,9 @@ pub(crate) fn expression(expr: &Expr, checker: &mut Checker) {
                 range: _,
             },
         ) => {
+            if checker.enabled(Rule::UnnecessaryListIndexLookup) {
+                pylint::rules::unnecessary_list_index_lookup_comprehension(checker, expr);
+            }
             if checker.enabled(Rule::UnnecessaryComprehension) {
                 flake8_comprehensions::rules::unnecessary_list_set_comprehension(
                     checker, expr, elt, generators,
@@ -1319,6 +1322,9 @@ pub(crate) fn expression(expr: &Expr, checker: &mut Checker) {
                 range: _,
             },
         ) => {
+            if checker.enabled(Rule::UnnecessaryListIndexLookup) {
+                pylint::rules::unnecessary_list_index_lookup_comprehension(checker, expr);
+            }
             if checker.enabled(Rule::UnnecessaryComprehension) {
                 flake8_comprehensions::rules::unnecessary_list_set_comprehension(
                     checker, expr, elt, generators,
@@ -1342,6 +1348,9 @@ pub(crate) fn expression(expr: &Expr, checker: &mut Checker) {
             generators,
             range: _,
         }) => {
+            if checker.enabled(Rule::UnnecessaryListIndexLookup) {
+                pylint::rules::unnecessary_list_index_lookup_comprehension(checker, expr);
+            }
             if checker.enabled(Rule::UnnecessaryComprehension) {
                 flake8_comprehensions::rules::unnecessary_dict_comprehension(
                     checker, expr, key, value, generators,
@@ -1366,6 +1375,9 @@ pub(crate) fn expression(expr: &Expr, checker: &mut Checker) {
                 range: _,
             },
         ) => {
+            if checker.enabled(Rule::UnnecessaryListIndexLookup) {
+                pylint::rules::unnecessary_list_index_lookup_comprehension(checker, expr);
+            }
             if checker.enabled(Rule::FunctionUsesLoopVariable) {
                 flake8_bugbear::rules::function_uses_loop_variable(checker, &Node::Expr(expr));
             }

crates/ruff_linter/src/rules/pylint/rules/unnecessary_list_index_lookup.rs

@@ -102,63 +102,119 @@ impl<'a> Visitor<'_> for SubscriptVisitor<'a> {
 
 /// PLR1736
 pub(crate) fn unnecessary_list_index_lookup(checker: &mut Checker, stmt_for: &StmtFor) {
+    let Some((sequence, index_name, value_name)) =
+        enumerate_items(checker, &stmt_for.iter, &stmt_for.target)
+    else {
+        return;
+    };
+
+    let mut visitor = SubscriptVisitor::new(&sequence, &index_name);
+
+    visitor.visit_body(&stmt_for.body);
+    visitor.visit_body(&stmt_for.orelse);
+
+    for range in visitor.diagnostic_ranges {
+        let mut diagnostic = Diagnostic::new(UnnecessaryListIndexLookup, range);
+
+        diagnostic.set_fix(Fix::safe_edit(Edit::range_replacement(
+            value_name.clone(),
+            range,
+        )));
+
+        checker.diagnostics.push(diagnostic);
+    }
+}
+
+/// PLR1736
+pub(crate) fn unnecessary_list_index_lookup_comprehension(checker: &mut Checker, expr: &Expr) {
+    match expr {
+        Expr::GeneratorExp(ast::ExprGeneratorExp {
+            elt, generators, ..
+        })
+        | Expr::DictComp(ast::ExprDictComp {
+            value: elt,
+            generators,
+            ..
+        })
+        | Expr::SetComp(ast::ExprSetComp {
+            elt, generators, ..
+        })
+        | Expr::ListComp(ast::ExprListComp {
+            elt, generators, ..
+        }) => {
+            for comp in generators {
+                if let Some((sequence, index_name, value_name)) =
+                    enumerate_items(checker, &comp.iter, &comp.target)
+                {
+                    let mut visitor = SubscriptVisitor::new(&sequence, &index_name);
+
+                    visitor.visit_expr(elt.as_ref());
+
+                    for range in visitor.diagnostic_ranges {
+                        let mut diagnostic = Diagnostic::new(UnnecessaryListIndexLookup, range);
+
+                        diagnostic.set_fix(Fix::safe_edit(Edit::range_replacement(
+                            value_name.clone(),
+                            range,
+                        )));
+
+                        checker.diagnostics.push(diagnostic);
+                    }
+                }
+            }
+        }
+        _ => (),
+    }
+}
+
+fn enumerate_items(
+    checker: &mut Checker,
+    call_expr: &Expr,
+    tuple_expr: &Expr,
+) -> Option<(String, String, String)> {
     let Expr::Call(ast::ExprCall {
         func, arguments, ..
-    }) = stmt_for.iter.as_ref()
+    }) = call_expr
     else {
-        return;
+        return None;
     };
 
     // Check that the function is the `enumerate` builtin.
     let Expr::Name(ast::ExprName { id, .. }) = func.as_ref() else {
-        return;
+        return None;
     };
     if id != "enumerate" {
-        return;
+        return None;
     };
     if !checker.semantic().is_builtin("enumerate") {
-        return;
+        return None;
     };
 
-    let Expr::Tuple(ast::ExprTuple { elts, .. }) = stmt_for.target.as_ref() else {
-        return;
+    let Expr::Tuple(ast::ExprTuple { elts, .. }) = tuple_expr else {
+        return None;
     };
     let [index, value] = elts.as_slice() else {
-        return;
+        return None;
     };
 
     // Grab the variable names
     let Expr::Name(ast::ExprName { id: index_name, .. }) = index else {
-        return;
+        return None;
     };
 
     let Expr::Name(ast::ExprName { id: value_name, .. }) = value else {
-        return;
+        return None;
     };
 
     // If either of the variable names are intentionally ignored by naming them `_`, then don't emit
     if index_name == "_" || value_name == "_" {
-        return;
+        return None;
     }
 
     // Get the first argument of the enumerate call
     let Some(Expr::Name(ast::ExprName { id: sequence, .. })) = arguments.args.first() else {
-        return;
+        return None;
     };
 
-    let mut visitor = SubscriptVisitor::new(sequence, index_name);
-
-    visitor.visit_body(&stmt_for.body);
-    visitor.visit_body(&stmt_for.orelse);
-
-    for range in visitor.diagnostic_ranges {
-        let mut diagnostic = Diagnostic::new(UnnecessaryListIndexLookup, range);
-
-        diagnostic.set_fix(Fix::safe_edit(Edit::range_replacement(
-            value_name.clone(),
-            range,
-        )));
-
-        checker.diagnostics.push(diagnostic);
-    }
+    Some((sequence.clone(), index_name.clone(), value_name.clone()))
 }