From 7e13565d1feb8af7a2b8c6fe0e1b8066195c0cc9 Mon Sep 17 00:00:00 2001
From: Alex Waygood <alex.waygood@gmail.com>
Date: Wed, 27 Nov 2024 18:18:46 +0000
Subject: [PATCH] Fix false negative on lambdas inside decorators

---
 .../resources/test/fixtures/refurb/FURB118.py | 18 ++++++
 .../refurb/rules/reimplemented_operator.rs    | 12 +++-
 ...es__refurb__tests__FURB118_FURB118.py.snap | 58 +++++++++++++++++++
 3 files changed, 87 insertions(+), 1 deletion(-)

diff --git a/crates/ruff_linter/resources/test/fixtures/refurb/FURB118.py b/crates/ruff_linter/resources/test/fixtures/refurb/FURB118.py
index 693cb2b2d0f937..f49b068cf5511d 100644
--- a/crates/ruff_linter/resources/test/fixtures/refurb/FURB118.py
+++ b/crates/ruff_linter/resources/test/fixtures/refurb/FURB118.py
@@ -102,3 +102,21 @@ def x(self, other):
 
 class Bar:
     y = lambda self, other: self == other
+
+from typing import Callable
+class Baz:
+    z: Callable = lambda self, other: self == other
+
+
+# lambdas used in decorators do not constitute method definitions,
+# so these *should* be flagged:
+class TheLambdasHereAreNotMethods:
+    @pytest.mark.parametrize(
+        "slicer, expected",
+        [
+            (lambda x: x[-2:], "foo"),
+            (lambda x: x[-5:-3], "bar"),
+        ],
+    )
+    def test_inlet_asset_alias_extra_slice(self, slicer, expected):
+        assert slice("whatever") == expected
diff --git a/crates/ruff_linter/src/rules/refurb/rules/reimplemented_operator.rs b/crates/ruff_linter/src/rules/refurb/rules/reimplemented_operator.rs
index cd5896825629a5..ad68ed8509fa36 100644
--- a/crates/ruff_linter/src/rules/refurb/rules/reimplemented_operator.rs
+++ b/crates/ruff_linter/src/rules/refurb/rules/reimplemented_operator.rs
@@ -92,7 +92,13 @@ impl Violation for ReimplementedOperator {
 /// FURB118
 pub(crate) fn reimplemented_operator(checker: &mut Checker, target: &FunctionLike) {
     // Ignore methods, whether defined using the `def` keyword or via a `lambda` assignment.
-    if checker.semantic().current_scope().kind.is_class() {
+    if checker.semantic().current_scope().kind.is_class()
+        && (target.is_function_def()
+            || checker
+                .semantic()
+                .current_statements()
+                .any(|stmt| matches!(stmt, Stmt::AnnAssign(_) | Stmt::Assign(_))))
+    {
         return;
     }
 
@@ -152,6 +158,10 @@ impl FunctionLike<'_> {
         }
     }
 
+    const fn is_function_def(&self) -> bool {
+        matches!(self, Self::Function(_))
+    }
+
     /// Return the body of the function-like node.
     ///
     /// If the node is a function definition that consists of more than a single return statement,
diff --git a/crates/ruff_linter/src/rules/refurb/snapshots/ruff_linter__rules__refurb__tests__FURB118_FURB118.py.snap b/crates/ruff_linter/src/rules/refurb/snapshots/ruff_linter__rules__refurb__tests__FURB118_FURB118.py.snap
index 1bc82ac000cf23..d245b7c98bc57b 100644
--- a/crates/ruff_linter/src/rules/refurb/snapshots/ruff_linter__rules__refurb__tests__FURB118_FURB118.py.snap
+++ b/crates/ruff_linter/src/rules/refurb/snapshots/ruff_linter__rules__refurb__tests__FURB118_FURB118.py.snap
@@ -949,3 +949,61 @@ FURB118.py:95:17: FURB118 [*] Use `operator.itemgetter((1,          2))` instead
 96 97 | 
 97 98 | 
 98 99 | # All methods in classes are ignored, even those defined using lambdas:
+
+FURB118.py:117:14: FURB118 [*] Use `operator.itemgetter(slice(-2, None))` instead of defining a lambda
+    |
+115 |         "slicer, expected",
+116 |         [
+117 |             (lambda x: x[-2:], "foo"),
+    |              ^^^^^^^^^^^^^^^^ FURB118
+118 |             (lambda x: x[-5:-3], "bar"),
+119 |         ],
+    |
+    = help: Replace with `operator.itemgetter(slice(-2, None))`
+
+ℹ Unsafe fix
+104 104 |     y = lambda self, other: self == other
+105 105 | 
+106 106 | from typing import Callable
+    107 |+import operator
+107 108 | class Baz:
+108 109 |     z: Callable = lambda self, other: self == other
+109 110 | 
+--------------------------------------------------------------------------------
+114 115 |     @pytest.mark.parametrize(
+115 116 |         "slicer, expected",
+116 117 |         [
+117     |-            (lambda x: x[-2:], "foo"),
+    118 |+            (operator.itemgetter(slice(-2, None)), "foo"),
+118 119 |             (lambda x: x[-5:-3], "bar"),
+119 120 |         ],
+120 121 |     )
+
+FURB118.py:118:14: FURB118 [*] Use `operator.itemgetter(slice(-5, -3))` instead of defining a lambda
+    |
+116 |         [
+117 |             (lambda x: x[-2:], "foo"),
+118 |             (lambda x: x[-5:-3], "bar"),
+    |              ^^^^^^^^^^^^^^^^^^ FURB118
+119 |         ],
+120 |     )
+    |
+    = help: Replace with `operator.itemgetter(slice(-5, -3))`
+
+ℹ Unsafe fix
+104 104 |     y = lambda self, other: self == other
+105 105 | 
+106 106 | from typing import Callable
+    107 |+import operator
+107 108 | class Baz:
+108 109 |     z: Callable = lambda self, other: self == other
+109 110 | 
+--------------------------------------------------------------------------------
+115 116 |         "slicer, expected",
+116 117 |         [
+117 118 |             (lambda x: x[-2:], "foo"),
+118     |-            (lambda x: x[-5:-3], "bar"),
+    119 |+            (operator.itemgetter(slice(-5, -3)), "bar"),
+119 120 |         ],
+120 121 |     )
+121 122 |     def test_inlet_asset_alias_extra_slice(self, slicer, expected):