Avoid key-in-dict violations for self accesses (#6165)

Closes #6163.

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

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) =

crates/ruff/src/rules/flake8_simplify/snapshots/ruff__rules__flake8_simplify__tests__SIM118_SIM118.py.snap

@@ -265,13 +265,16 @@ 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()`
    |
 30 | (k for k in obj.keys())  # SIM118
 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 |