ignore rule when underscore is used as a variable

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

@@ -1,7 +1,21 @@
 letters = ["a", "b", "c"]
 
-for index, letter in enumerate(letters):
-    print(letters[index])  # PLR1736
-    blah = letters[index]  # PLR1736
-    letters[index] = letters[index]  # PLR1736 (on the right hand)
-    letters[index] = "d"  # Ok
+
+def fix_these():
+    for index, letter in enumerate(letters):
+        print(letters[index])  # PLR1736
+        blah = letters[index]  # PLR1736
+        letters[index] = letters[index]  # PLR1736 (on the right hand)
+
+
+def dont_fix_these():
+    for index, letter in enumerate(letters):
+        letters[index] = "d"  # Ok
+
+
+def value_intentionally_unused():
+    for index, _ in enumerate(letters):
+        print(letters[index])  # Ok
+        blah = letters[index]  # Ok
+        letters[index] = letters[index]  # Ok
+        letters[index] = "d"  # Ok

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

@@ -128,6 +128,11 @@ pub(crate) fn unnecessary_list_index_lookup(checker: &mut Checker, stmt_for: &St
         return;
     };
 
+    // If either of the variable names are intentionally ignored by naming them `_`, then don't emit
+    if index_name == "_" || value_name == "_" {
+        return;
+    }
+
     // Get the first argument of the enumerate call
     let Some(Expr::Name(ast::ExprName { id: sequence, .. })) = arguments.args.first() else {
         return;

crates/ruff_linter/src/rules/pylint/snapshots/ruff_linter__rules__pylint__tests__PLR1736_unnecessary_list_index_lookup.py.snap

@@ -1,62 +1,64 @@
 ---
 source: crates/ruff_linter/src/rules/pylint/mod.rs
 ---
-unnecessary_list_index_lookup.py:4:11: PLR1736 [*] Unnecessary list index lookup
+unnecessary_list_index_lookup.py:6:15: PLR1736 [*] Unnecessary list index lookup
   |
-3 | for index, letter in enumerate(letters):
-4 |     print(letters[index])  # PLR1736
-  |           ^^^^^^^^^^^^^^ PLR1736
-5 |     blah = letters[index]  # PLR1736
-6 |     letters[index] = letters[index]  # PLR1736 (on the right hand)
+4 | def fix_these():
+5 |     for index, letter in enumerate(letters):
+6 |         print(letters[index])  # PLR1736
+  |               ^^^^^^^^^^^^^^ PLR1736
+7 |         blah = letters[index]  # PLR1736
+8 |         letters[index] = letters[index]  # PLR1736 (on the right hand)
   |
   = help: Remove unnecessary list index lookup
 
 ℹ Fix
-1 1 | letters = ["a", "b", "c"]
-2 2 | 
-3 3 | for index, letter in enumerate(letters):
-4   |-    print(letters[index])  # PLR1736
-  4 |+    print(letter)  # PLR1736
-5 5 |     blah = letters[index]  # PLR1736
-6 6 |     letters[index] = letters[index]  # PLR1736 (on the right hand)
-7 7 |     letters[index] = "d"  # Ok
+3 3 | 
+4 4 | def fix_these():
+5 5 |     for index, letter in enumerate(letters):
+6   |-        print(letters[index])  # PLR1736
+  6 |+        print(letter)  # PLR1736
+7 7 |         blah = letters[index]  # PLR1736
+8 8 |         letters[index] = letters[index]  # PLR1736 (on the right hand)
+9 9 | 
 
-unnecessary_list_index_lookup.py:5:12: PLR1736 [*] Unnecessary list index lookup
+unnecessary_list_index_lookup.py:7:16: PLR1736 [*] Unnecessary list index lookup
   |
-3 | for index, letter in enumerate(letters):
-4 |     print(letters[index])  # PLR1736
-5 |     blah = letters[index]  # PLR1736
-  |            ^^^^^^^^^^^^^^ PLR1736
-6 |     letters[index] = letters[index]  # PLR1736 (on the right hand)
-7 |     letters[index] = "d"  # Ok
+5 |     for index, letter in enumerate(letters):
+6 |         print(letters[index])  # PLR1736
+7 |         blah = letters[index]  # PLR1736
+  |                ^^^^^^^^^^^^^^ PLR1736
+8 |         letters[index] = letters[index]  # PLR1736 (on the right hand)
   |
   = help: Remove unnecessary list index lookup
 
 ℹ Fix
-2 2 | 
-3 3 | for index, letter in enumerate(letters):
-4 4 |     print(letters[index])  # PLR1736
-5   |-    blah = letters[index]  # PLR1736
-  5 |+    blah = letter  # PLR1736
-6 6 |     letters[index] = letters[index]  # PLR1736 (on the right hand)
-7 7 |     letters[index] = "d"  # Ok
+4 4 | def fix_these():
+5 5 |     for index, letter in enumerate(letters):
+6 6 |         print(letters[index])  # PLR1736
+7   |-        blah = letters[index]  # PLR1736
+  7 |+        blah = letter  # PLR1736
+8 8 |         letters[index] = letters[index]  # PLR1736 (on the right hand)
+9 9 | 
+10 10 | 
 
-unnecessary_list_index_lookup.py:6:22: PLR1736 [*] Unnecessary list index lookup
+unnecessary_list_index_lookup.py:8:26: PLR1736 [*] Unnecessary list index lookup
   |
-4 |     print(letters[index])  # PLR1736
-5 |     blah = letters[index]  # PLR1736
-6 |     letters[index] = letters[index]  # PLR1736 (on the right hand)
-  |                      ^^^^^^^^^^^^^^ PLR1736
-7 |     letters[index] = "d"  # Ok
+6 |         print(letters[index])  # PLR1736
+7 |         blah = letters[index]  # PLR1736
+8 |         letters[index] = letters[index]  # PLR1736 (on the right hand)
+  |                          ^^^^^^^^^^^^^^ PLR1736
   |
   = help: Remove unnecessary list index lookup
 
 ℹ Fix
-3 3 | for index, letter in enumerate(letters):
-4 4 |     print(letters[index])  # PLR1736
-5 5 |     blah = letters[index]  # PLR1736
-6   |-    letters[index] = letters[index]  # PLR1736 (on the right hand)
-  6 |+    letters[index] = letter  # PLR1736 (on the right hand)
-7 7 |     letters[index] = "d"  # Ok
+5 5 |     for index, letter in enumerate(letters):
+6 6 |         print(letters[index])  # PLR1736
+7 7 |         blah = letters[index]  # PLR1736
+8   |-        letters[index] = letters[index]  # PLR1736 (on the right hand)
+  8 |+        letters[index] = letter  # PLR1736 (on the right hand)
+9 9 | 
+10 10 | 
+11 11 | def dont_fix_these():