From 4802c7c7d892967c5a583598c1381257a24e6e2d Mon Sep 17 00:00:00 2001
From: Charlie Marsh <charlie.r.marsh@gmail.com>
Date: Fri, 28 Jul 2023 23:35:26 -0400
Subject: [PATCH] Avoid key-in-dict violations for `self` accesses (#6165)

Closes https://github.com/astral-sh/ruff/issues/6163.
---
 .../test/fixtures/flake8_simplify/SIM118.py        | 10 ++++++++++
 .../src/rules/flake8_simplify/rules/key_in_dict.rs | 14 +++++++++++++-
 ...__flake8_simplify__tests__SIM118_SIM118.py.snap |  6 ++++++
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/crates/ruff/resources/test/fixtures/flake8_simplify/SIM118.py b/crates/ruff/resources/test/fixtures/flake8_simplify/SIM118.py
index 308cd2e8571d2..6f86a62204bec 100644
--- a/crates/ruff/resources/test/fixtures/flake8_simplify/SIM118.py
+++ b/crates/ruff/resources/test/fixtures/flake8_simplify/SIM118.py
@@ -30,3 +30,13 @@
 (k for k in obj.keys())  # SIM118
 
 key in (obj or {}).keys()  # SIM118
+
+from typing import KeysView
+
+
+class Foo:
+    def keys(self) -> KeysView[object]:
+        ...
+
+    def __contains__(self, key: object) -> bool:
+        return key in self.keys()  # OK
diff --git a/crates/ruff/src/rules/flake8_simplify/rules/key_in_dict.rs b/crates/ruff/src/rules/flake8_simplify/rules/key_in_dict.rs
index f1b6c7488eca6..d77a6479a5860 100644
--- a/crates/ruff/src/rules/flake8_simplify/rules/key_in_dict.rs
+++ b/crates/ruff/src/rules/flake8_simplify/rules/key_in_dict.rs
@@ -82,13 +82,25 @@ fn key_in_dict(
         return;
     }
 
-    let Expr::Attribute(ast::ExprAttribute { attr, .. }) = func.as_ref() else {
+    let Expr::Attribute(ast::ExprAttribute { attr, value, .. }) = func.as_ref() else {
         return;
     };
     if attr != "keys" {
         return;
     }
 
+    // Ignore `self.keys()`, which will almost certainly be intentional, as in:
+    // ```python
+    // def __contains__(self, key: object) -> bool:
+    //     return key in self.keys()
+    // ```
+    if value
+        .as_name_expr()
+        .map_or(false, |name| matches!(name.id.as_str(), "self"))
+    {
+        return;
+    }
+
     // Slice exact content to preserve formatting.
     let left_content = checker.locator().slice(left.range());
     let Ok(value_content) =
diff --git a/crates/ruff/src/rules/flake8_simplify/snapshots/ruff__rules__flake8_simplify__tests__SIM118_SIM118.py.snap b/crates/ruff/src/rules/flake8_simplify/snapshots/ruff__rules__flake8_simplify__tests__SIM118_SIM118.py.snap
index 972ccb6d590d3..05cdf5c898408 100644
--- a/crates/ruff/src/rules/flake8_simplify/snapshots/ruff__rules__flake8_simplify__tests__SIM118_SIM118.py.snap
+++ b/crates/ruff/src/rules/flake8_simplify/snapshots/ruff__rules__flake8_simplify__tests__SIM118_SIM118.py.snap
@@ -265,6 +265,7 @@ SIM118.py:30:8: SIM118 [*] Use `k in obj` instead of `k in obj.keys()`
    30 |+(k for k in obj)  # SIM118
 31 31 | 
 32 32 | key in (obj or {}).keys()  # SIM118
+33 33 | 
 
 SIM118.py:32:1: SIM118 [*] Use `key in (obj or {})` instead of `key in (obj or {}).keys()`
    |
@@ -272,6 +273,8 @@ SIM118.py:32:1: SIM118 [*] Use `key in (obj or {})` instead of `key in (obj or {
 31 | 
 32 | key in (obj or {}).keys()  # SIM118
    | ^^^^^^^^^^^^^^^^^^^^^^^^^ SIM118
+33 | 
+34 | from typing import KeysView
    |
    = help: Convert to `key in (obj or {})`
 
@@ -281,5 +284,8 @@ SIM118.py:32:1: SIM118 [*] Use `key in (obj or {})` instead of `key in (obj or {
 31 31 | 
 32    |-key in (obj or {}).keys()  # SIM118
    32 |+key in (obj or {})  # SIM118
+33 33 | 
+34 34 | from typing import KeysView
+35 35 |