[flake8-pyi] Add "replace with Self" fix (PYI019) (#14238)

Co-authored-by: Micha Reiser <[email protected]>

crates/ruff_linter/resources/test/fixtures/flake8_pyi/PYI019.py

@@ -52,3 +52,38 @@ class CustomClassMethod:
    # in the settings for this test:
    @foo_classmethod
    def foo[S](cls: type[S]) -> S: ...  # PYI019
+
+
+_S695 = TypeVar("_S695", bound="PEP695Fix")
+
+# Only .pyi gets fixes, no fixes for .py
+class PEP695Fix:
+    def __new__[S: PEP695Fix](cls: type[S]) -> S: ...
+
+    def __init_subclass__[S](cls: type[S]) -> S: ...
+
+    def __neg__[S: PEP695Fix](self: S) -> S: ...
+
+    def __pos__[S](self: S) -> S: ...
+
+    def __add__[S: PEP695Fix](self: S, other: S) -> S: ...
+
+    def __sub__[S](self: S, other: S) -> S: ...
+
+    @classmethod
+    def class_method_bound[S: PEP695Fix](cls: type[S]) -> S: ...
+
+    @classmethod
+    def class_method_unbound[S](cls: type[S]) -> S: ...
+
+    def instance_method_bound[S: PEP695Fix](self: S) -> S: ...
+
+    def instance_method_unbound[S](self: S) -> S: ...
+
+    def instance_method_bound_with_another_parameter[S: PEP695Fix](self: S, other: S) -> S: ...
+
+    def instance_method_unbound_with_another_parameter[S](self: S, other: S) -> S: ...
+
+    def multiple_type_vars[S, *Ts, T](self: S, other: S, /, *args: *Ts, a: T, b: list[T]) -> S: ...
+
+    def mixing_old_and_new_style_type_vars[T](self: _S695, a: T, b: T) -> _S695: ...

crates/ruff_linter/resources/test/fixtures/flake8_pyi/PYI019.pyi

@@ -52,3 +52,38 @@ class CustomClassMethod:
    # in the settings for this test:
    @foo_classmethod
    def foo[S](cls: type[S]) -> S: ...  # PYI019
+
+
+_S695 = TypeVar("_S695", bound="PEP695Fix")
+
+# Only .pyi gets fixes, no fixes for .py
+class PEP695Fix:
+    def __new__[S: PEP695Fix](cls: type[S]) -> S: ...
+
+    def __init_subclass__[S](cls: type[S]) -> S: ...
+
+    def __neg__[S: PEP695Fix](self: S) -> S: ...
+
+    def __pos__[S](self: S) -> S: ...
+
+    def __add__[S: PEP695Fix](self: S, other: S) -> S: ...
+
+    def __sub__[S](self: S, other: S) -> S: ...
+
+    @classmethod
+    def class_method_bound[S: PEP695Fix](cls: type[S]) -> S: ...
+
+    @classmethod
+    def class_method_unbound[S](cls: type[S]) -> S: ...
+
+    def instance_method_bound[S: PEP695Fix](self: S) -> S: ...
+
+    def instance_method_unbound[S](self: S) -> S: ...
+
+    def instance_method_bound_with_another_parameter[S: PEP695Fix](self: S, other: S) -> S: ...
+
+    def instance_method_unbound_with_another_parameter[S](self: S, other: S) -> S: ...
+
+    def multiple_type_vars[S, *Ts, T](self: S, other: S, /, *args: *Ts, a: T, b: list[T]) -> S: ...
+
+    def mixing_old_and_new_style_type_vars[T](self: _S695, a: T, b: T) -> _S695: ...

crates/ruff_linter/src/checkers/ast/analyze/statement.rs

@@ -81,7 +81,7 @@ pub(crate) fn statement(stmt: &Stmt, checker: &mut Checker) {
                 returns,
                 parameters,
                 body,
-                type_params,
+                type_params: _,
                 range: _,
             },
         ) => {
@@ -160,14 +160,7 @@ pub(crate) fn statement(stmt: &Stmt, checker: &mut Checker) {
                 flake8_pyi::rules::bad_generator_return_type(function_def, checker);
             }
             if checker.enabled(Rule::CustomTypeVarReturnType) {
-                flake8_pyi::rules::custom_type_var_return_type(
-                    checker,
-                    name,
-                    decorator_list,
-                    returns.as_ref().map(AsRef::as_ref),
-                    parameters,
-                    type_params.as_deref(),
-                );
+                flake8_pyi::rules::custom_type_var_return_type(checker, function_def);
             }
             if checker.source_type.is_stub() {
                 if checker.enabled(Rule::StrOrReprDefinedInStub) {

crates/ruff_linter/src/rules/flake8_pyi/mod.rs

@@ -152,6 +152,23 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn custom_classmethod_rules_preview() -> Result<()> {
+        let diagnostics = test_path(
+            Path::new("flake8_pyi/PYI019.pyi"),
+            &settings::LinterSettings {
+                pep8_naming: pep8_naming::settings::Settings {
+                    classmethod_decorators: vec!["foo_classmethod".to_string()],
+                    ..pep8_naming::settings::Settings::default()
+                },
+                preview: PreviewMode::Enabled,
+                ..settings::LinterSettings::for_rule(Rule::CustomTypeVarReturnType)
+            },
+        )?;
+        assert_messages!(diagnostics);
+        Ok(())
+    }
+
     #[test_case(Rule::TypeAliasWithoutAnnotation, Path::new("PYI026.py"))]
     #[test_case(Rule::TypeAliasWithoutAnnotation, Path::new("PYI026.pyi"))]
     fn py38(rule_code: Rule, path: &Path) -> Result<()> {