Fix N804 class method with positional only args (#836)

resources/test/fixtures/N804.py

@@ -30,6 +30,14 @@ class Class:
     def __init_subclass__(self, default_name, **kwargs):
         ...
 
+    @classmethod
+    def class_method_with_positional_only_argument(cls, x, /, other):
+        ...
+
+    @classmethod
+    def bad_class_method_with_positional_only_argument(self, x, /, other):
+        ...
+
 
 class MetaClass(ABCMeta):
     def bad_method(self):

src/pep8_naming/checks.rs

@@ -74,7 +74,14 @@ pub fn invalid_first_argument_name_for_class_method(
         ),
         FunctionType::ClassMethod
     ) {
-        if let Some(arg) = args.args.first() {
+        if let Some(arg) = args.posonlyargs.first() {
+            if arg.node.arg != "cls" {
+                return Some(Check::new(
+                    CheckKind::InvalidFirstArgumentNameForClassMethod,
+                    Range::from_located(arg),
+                ));
+            }
+        } else if let Some(arg) = args.args.first() {
             if arg.node.arg != "cls" {
                 return Some(Check::new(
                     CheckKind::InvalidFirstArgumentNameForClassMethod,

src/snapshots/ruff__linter__tests__N804_N804.py.snap

@@ -12,10 +12,18 @@ expression: checks
   fix: ~
 - kind: InvalidFirstArgumentNameForClassMethod
   location:
-    row: 35
+    row: 38
+    column: 55
+  end_location:
+    row: 38
+    column: 59
+  fix: ~
+- kind: InvalidFirstArgumentNameForClassMethod
+  location:
+    row: 43
     column: 19
   end_location:
-    row: 35
+    row: 43
     column: 23
   fix: ~