[pep8-naming] Suppress fix for N804 and N805 if the recommend name is already used

crates/ruff_linter/resources/test/fixtures/pep8_naming/N804.py

@@ -81,3 +81,9 @@ def func(x):
 class Bar(type(foo)):
     def foo_method(self):
         pass
+
+# https://github.com/astral-sh/ruff/issues/18459
+class Example:
+    @classmethod
+    def function(this):
+        cls = 1234

crates/ruff_linter/resources/test/fixtures/pep8_naming/N805.py

@@ -134,3 +134,9 @@ def __subclasscheck__(cls, other): ...
 
 class MyProtocolMeta(type(Protocol)):
     def __subclasscheck__(cls, other): ...
+
+
+# https://github.com/astral-sh/ruff/issues/18459
+class C:
+    def f(this):
+        self = 123

crates/ruff_linter/src/rules/pep8_naming/rules/invalid_first_argument_name.rs

@@ -11,7 +11,7 @@ use ruff_text_size::{Ranged, TextRange};
 
 use crate::checkers::ast::{Checker, DiagnosticGuard};
 use crate::registry::Rule;
-use crate::renamer::Renamer;
+use crate::renamer::{Renamer, ShadowedKind};
 use crate::{Fix, Violation};
 
 /// ## What it does
@@ -272,6 +272,7 @@ pub(crate) fn invalid_first_argument_name(checker: &Checker, scope: &Scope) {
         function_type.diagnostic_kind(checker, self_or_cls.name.to_string(), self_or_cls.range());
     diagnostic.try_set_optional_fix(|| {
         rename_parameter(
+            checker,
             scope,
             self_or_cls,
             parameters,
@@ -284,6 +285,7 @@ pub(crate) fn invalid_first_argument_name(checker: &Checker, scope: &Scope) {
 
 /// Rename the first parameter to `self` or `cls`, if no other parameter has the target name.
 fn rename_parameter(
+    checker: &Checker,
     scope: &Scope<'_>,
     self_or_cls: &ast::Parameter,
     parameters: &ast::Parameters,
@@ -299,6 +301,16 @@ fn rename_parameter(
     {
         return Ok(None);
     }
+    let binding = scope
+        .get(&self_or_cls.name)
+        .map(|binding_id| semantic.binding(binding_id))
+        .unwrap();
+
+    // Don't provide autofix if `self` or `cls` is already defined in the scope.
+    if ShadowedKind::new(binding, function_type.valid_first_argument_name(), checker).shadows_any()
+    {
+        return Ok(None);
+    }
 
     let (edit, rest) = Renamer::rename(
         &self_or_cls.name,

crates/ruff_linter/src/rules/pep8_naming/snapshots/ruff_linter__rules__pep8_naming__tests__N804_N804.py.snap

@@ -153,3 +153,13 @@ N804.py:74:20: N804 [*] First argument of a class method should be named `cls`
 76 76 | 
 77 77 | def func(x):
 78 78 |     return x
+
+N804.py:88:18: N804 First argument of a class method should be named `cls`
+   |
+86 | class Example:
+87 |     @classmethod
+88 |     def function(this):
+   |                  ^^^^ N804
+89 |         cls = 1234
+   |
+   = help: Rename `this` to `cls`

crates/ruff_linter/src/rules/pep8_naming/snapshots/ruff_linter__rules__pep8_naming__tests__N805_N805.py.snap

@@ -247,7 +247,7 @@ N805.py:115:20: N805 [*] First argument of a method should be named `self`
 119 119 |     def bad_method(this):
 120 120 |         self = this
 
-N805.py:119:20: N805 [*] First argument of a method should be named `self`
+N805.py:119:20: N805 First argument of a method should be named `self`
     |
 117 |         this
 118 |
@@ -257,18 +257,6 @@ N805.py:119:20: N805 [*] First argument of a method should be named `self`
     |
     = help: Rename `this` to `self`
 
-ℹ Unsafe fix
-116 116 |         this = this
-117 117 |         this
-118 118 | 
-119     |-    def bad_method(this):
-120     |-        self = this
-    119 |+    def bad_method(self):
-    120 |+        self = self
-121 121 | 
-122 122 | 
-123 123 | class RenamingWithNFKC:
-
 N805.py:124:17: N805 [*] First argument of a method should be named `self`
     |
 123 | class RenamingWithNFKC:
@@ -289,3 +277,13 @@ N805.py:124:17: N805 [*] First argument of a method should be named `self`
 126 126 | 
 127 127 | 
 128 128 | from typing import Protocol
+
+N805.py:141:11: N805 First argument of a method should be named `self`
+    |
+139 | # https://github.com/astral-sh/ruff/issues/18459
+140 | class C:
+141 |     def f(this):
+    |           ^^^^ N805
+142 |         self = 123
+    |
+    = help: Rename `this` to `self`

crates/ruff_linter/src/rules/pep8_naming/snapshots/ruff_linter__rules__pep8_naming__tests__classmethod_decorators.snap

@@ -190,7 +190,7 @@ N805.py:115:20: N805 [*] First argument of a method should be named `self`
 119 119 |     def bad_method(this):
 120 120 |         self = this
 
-N805.py:119:20: N805 [*] First argument of a method should be named `self`
+N805.py:119:20: N805 First argument of a method should be named `self`
     |
 117 |         this
 118 |
@@ -200,18 +200,6 @@ N805.py:119:20: N805 [*] First argument of a method should be named `self`
     |
     = help: Rename `this` to `self`
 
-ℹ Unsafe fix
-116 116 |         this = this
-117 117 |         this
-118 118 | 
-119     |-    def bad_method(this):
-120     |-        self = this
-    119 |+    def bad_method(self):
-    120 |+        self = self
-121 121 | 
-122 122 | 
-123 123 | class RenamingWithNFKC:
-
 N805.py:124:17: N805 [*] First argument of a method should be named `self`
     |
 123 | class RenamingWithNFKC:
@@ -232,3 +220,13 @@ N805.py:124:17: N805 [*] First argument of a method should be named `self`
 126 126 | 
 127 127 | 
 128 128 | from typing import Protocol
+
+N805.py:141:11: N805 First argument of a method should be named `self`
+    |
+139 | # https://github.com/astral-sh/ruff/issues/18459
+140 | class C:
+141 |     def f(this):
+    |           ^^^^ N805
+142 |         self = 123
+    |
+    = help: Rename `this` to `self`

crates/ruff_linter/src/rules/pep8_naming/snapshots/ruff_linter__rules__pep8_naming__tests__staticmethod_decorators.snap

@@ -228,7 +228,7 @@ N805.py:115:20: N805 [*] First argument of a method should be named `self`
 119 119 |     def bad_method(this):
 120 120 |         self = this
 
-N805.py:119:20: N805 [*] First argument of a method should be named `self`
+N805.py:119:20: N805 First argument of a method should be named `self`
     |
 117 |         this
 118 |
@@ -238,18 +238,6 @@ N805.py:119:20: N805 [*] First argument of a method should be named `self`
     |
     = help: Rename `this` to `self`
 
-ℹ Unsafe fix
-116 116 |         this = this
-117 117 |         this
-118 118 | 
-119     |-    def bad_method(this):
-120     |-        self = this
-    119 |+    def bad_method(self):
-    120 |+        self = self
-121 121 | 
-122 122 | 
-123 123 | class RenamingWithNFKC:
-
 N805.py:124:17: N805 [*] First argument of a method should be named `self`
     |
 123 | class RenamingWithNFKC:
@@ -270,3 +258,13 @@ N805.py:124:17: N805 [*] First argument of a method should be named `self`
 126 126 | 
 127 127 | 
 128 128 | from typing import Protocol
+
+N805.py:141:11: N805 First argument of a method should be named `self`
+    |
+139 | # https://github.com/astral-sh/ruff/issues/18459
+140 | class C:
+141 |     def f(this):
+    |           ^^^^ N805
+142 |         self = 123
+    |
+    = help: Rename `this` to `self`