[flake8-pyi] Fix custom-typevar-for-self with string annotations (PYI019)

crates/ruff_linter/resources/test/fixtures/flake8_pyi/PYI019_0.py

@@ -181,3 +181,34 @@ def m[S](self: S) -> S:
 class MetaTestClass(type):
     def m(cls: MetaType) -> MetaType:
         return cls
+
+
+from __future__ import annotations
+
+class BadClassWithStringTypeHints:
+    def bad_instance_method_with_string_annotations(self: "_S", arg: str) -> "_S": ... # PYI019
+
+    @classmethod
+    def bad_class_method_with_string_annotations(cls: "type[_S]") -> "_S": ... # PYI019
+
+
+    @classmethod
+    def bad_class_method_with_mixed_annotations_1(cls: "type[_S]") -> _S: ... # PYI019
+
+
+    @classmethod
+    def bad_class_method_with_mixed_annotations_1(cls: type[_S]) -> "_S": ... # PYI019
+
+
+class BadSubscriptReturnTypeWithStringTypeHints:
+    @classmethod
+    def m[S](cls: "type[S]") -> "type[S]": ...  # PYI019
+
+
+class GoodClassWiStringTypeHints:
+    @classmethod
+    def good_cls_method_with_mixed_annotations(cls: "type[Self]", arg: str) -> Self: ...
+    @staticmethod
+    def good_static_method_with_string_annotations(arg: "_S") -> "_S": ...
+    @classmethod
+    def good_class_method_with_args_string_annotations(cls, arg1: "_S", arg2: "_S") -> "_S": ...

crates/ruff_linter/resources/test/fixtures/flake8_pyi/PYI019_0.pyi

@@ -172,3 +172,36 @@ MetaType = TypeVar("MetaType")
 class MetaTestClass(type):
     def m(cls: MetaType) -> MetaType:
         return cls
+
+
+from __future__ import annotations
+
+
+class BadClassWithStringTypeHints:
+    def bad_instance_method_with_string_annotations(self: "_S", arg: str) -> "_S": ... # PYI019
+
+    @classmethod
+    def bad_class_method_with_string_annotations(cls: "type[_S]") -> "_S": ... # PYI019
+
+
+    @classmethod
+    def bad_class_method_with_mixed_annotations_1(cls: "type[_S]") -> _S: ... # PYI019
+
+
+    @classmethod
+    def bad_class_method_with_mixed_annotations_1(cls: type[_S]) -> "_S": ... # PYI019
+
+
+class BadSubscriptReturnTypeWithStringTypeHints:
+    @classmethod
+    def m[S](cls: "type[S]") -> "type[S]": ...  # PYI019
+
+
+class GoodClassWithStringTypeHints:
+    @classmethod
+    def good_cls_method_with_mixed_annotations(cls: "type[Self]", arg: str) -> Self: ...
+    @staticmethod
+    def good_static_method_with_string_annotations(arg: "_S") -> "_S": ...
+    @classmethod
+    def good_class_method_with_args_string_annotations(cls, arg1: "_S", arg2: "_S") -> "_S": ...
+

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

@@ -142,9 +142,23 @@ pub(crate) fn custom_type_var_instead_of_self(checker: &Checker, binding: &Bindi
         return;
     };
 
-    let Some(self_or_cls_annotation) = self_or_cls_parameter.annotation() else {
+    let Some(self_or_cls_annotation_unchecked) = self_or_cls_parameter.annotation() else {
         return;
     };
+    let self_or_cls_annotation = match self_or_cls_annotation_unchecked {
+        ast::Expr::StringLiteral(_) => {
+            let Some(literal_expr) = self_or_cls_annotation_unchecked.as_string_literal_expr()
+            else {
+                return;
+            };
+            let Ok(parsed_expr) = checker.parse_type_annotation(literal_expr) else {
+                return;
+            };
+            parsed_expr.expression()
+        }
+        ast::Expr::Subscript(_) | ast::Expr::Name(_) => self_or_cls_annotation_unchecked,
+        _ => return,
+    };
     let Some(parent_class) = current_scope.kind.as_class() else {
         return;
     };
@@ -202,7 +216,7 @@ pub(crate) fn custom_type_var_instead_of_self(checker: &Checker, binding: &Bindi
             function_def,
             custom_typevar,
             self_or_cls_parameter,
-            self_or_cls_annotation,
+            self_or_cls_annotation_unchecked,
         )
     });
 }

crates/ruff_linter/src/rules/flake8_pyi/snapshots/ruff_linter__rules__flake8_pyi__tests__PYI019_PYI019_0.py.snap

@@ -690,3 +690,96 @@ PYI019_0.py:173:10: PYI019 [*] Use `Self` instead of custom TypeVar `S`
 174 174 |         type S = int
 175 175 |         print(S)  # not a reference to the type variable, so not touched by the autofix
 176 176 |         return 42
+
+PYI019_0.py:189:52: PYI019 [*] Use `Self` instead of custom TypeVar `_S`
+    |
+188 | class BadClassWithStringTypeHints:
+189 |     def bad_instance_method_with_string_annotations(self: "_S", arg: str) -> "_S": ... # PYI019
+    |                                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI019
+190 |
+191 |     @classmethod
+    |
+    = help: Replace TypeVar `_S` with `Self`
+
+ℹ Safe fix
+186 186 | from __future__ import annotations
+187 187 | 
+188 188 | class BadClassWithStringTypeHints:
+189     |-    def bad_instance_method_with_string_annotations(self: "_S", arg: str) -> "_S": ... # PYI019
+    189 |+    def bad_instance_method_with_string_annotations(self, arg: str) -> "Self": ... # PYI019
+190 190 | 
+191 191 |     @classmethod
+192 192 |     def bad_class_method_with_string_annotations(cls: "type[_S]") -> "_S": ... # PYI019
+
+PYI019_0.py:192:49: PYI019 [*] Use `Self` instead of custom TypeVar `_S`
+    |
+191 |     @classmethod
+192 |     def bad_class_method_with_string_annotations(cls: "type[_S]") -> "_S": ... # PYI019
+    |                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^ PYI019
+    |
+    = help: Replace TypeVar `_S` with `Self`
+
+ℹ Safe fix
+189 189 |     def bad_instance_method_with_string_annotations(self: "_S", arg: str) -> "_S": ... # PYI019
+190 190 | 
+191 191 |     @classmethod
+192     |-    def bad_class_method_with_string_annotations(cls: "type[_S]") -> "_S": ... # PYI019
+    192 |+    def bad_class_method_with_string_annotations(cls) -> "Self": ... # PYI019
+193 193 | 
+194 194 | 
+195 195 |     @classmethod
+
+PYI019_0.py:196:50: PYI019 [*] Use `Self` instead of custom TypeVar `_S`
+    |
+195 |     @classmethod
+196 |     def bad_class_method_with_mixed_annotations_1(cls: "type[_S]") -> _S: ... # PYI019
+    |                                                  ^^^^^^^^^^^^^^^^^^^^^^^ PYI019
+    |
+    = help: Replace TypeVar `_S` with `Self`
+
+ℹ Safe fix
+193 193 | 
+194 194 | 
+195 195 |     @classmethod
+196     |-    def bad_class_method_with_mixed_annotations_1(cls: "type[_S]") -> _S: ... # PYI019
+    196 |+    def bad_class_method_with_mixed_annotations_1(cls) -> Self: ... # PYI019
+197 197 | 
+198 198 | 
+199 199 |     @classmethod
+
+PYI019_0.py:200:50: PYI019 [*] Use `Self` instead of custom TypeVar `_S`
+    |
+199 |     @classmethod
+200 |     def bad_class_method_with_mixed_annotations_1(cls: type[_S]) -> "_S": ... # PYI019
+    |                                                  ^^^^^^^^^^^^^^^^^^^^^^^ PYI019
+    |
+    = help: Replace TypeVar `_S` with `Self`
+
+ℹ Safe fix
+197 197 | 
+198 198 | 
+199 199 |     @classmethod
+200     |-    def bad_class_method_with_mixed_annotations_1(cls: type[_S]) -> "_S": ... # PYI019
+    200 |+    def bad_class_method_with_mixed_annotations_1(cls) -> "Self": ... # PYI019
+201 201 | 
+202 202 | 
+203 203 | class BadSubscriptReturnTypeWithStringTypeHints:
+
+PYI019_0.py:205:10: PYI019 [*] Use `Self` instead of custom TypeVar `S`
+    |
+203 | class BadSubscriptReturnTypeWithStringTypeHints:
+204 |     @classmethod
+205 |     def m[S](cls: "type[S]") -> "type[S]": ...  # PYI019
+    |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI019
+    |
+    = help: Replace TypeVar `S` with `Self`
+
+ℹ Safe fix
+202 202 | 
+203 203 | class BadSubscriptReturnTypeWithStringTypeHints:
+204 204 |     @classmethod
+205     |-    def m[S](cls: "type[S]") -> "type[S]": ...  # PYI019
+    205 |+    def m(cls) -> "type[Self]": ...  # PYI019
+206 206 | 
+207 207 | 
+208 208 | class GoodClassWiStringTypeHints:

crates/ruff_linter/src/rules/flake8_pyi/snapshots/ruff_linter__rules__flake8_pyi__tests__PYI019_PYI019_0.pyi.snap

@@ -682,3 +682,96 @@ PYI019_0.pyi:167:10: PYI019 [*] Use `Self` instead of custom TypeVar `S`
 168 168 | 
 169 169 | 
 170 170 | MetaType = TypeVar("MetaType")
+
+PYI019_0.pyi:181:52: PYI019 [*] Use `Self` instead of custom TypeVar `_S`
+    |
+180 | class BadClassWithStringTypeHints:
+181 |     def bad_instance_method_with_string_annotations(self: "_S", arg: str) -> "_S": ... # PYI019
+    |                                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI019
+182 |
+183 |     @classmethod
+    |
+    = help: Replace TypeVar `_S` with `Self`
+
+ℹ Safe fix
+178 178 | 
+179 179 | 
+180 180 | class BadClassWithStringTypeHints:
+181     |-    def bad_instance_method_with_string_annotations(self: "_S", arg: str) -> "_S": ... # PYI019
+    181 |+    def bad_instance_method_with_string_annotations(self, arg: str) -> "Self": ... # PYI019
+182 182 | 
+183 183 |     @classmethod
+184 184 |     def bad_class_method_with_string_annotations(cls: "type[_S]") -> "_S": ... # PYI019
+
+PYI019_0.pyi:184:49: PYI019 [*] Use `Self` instead of custom TypeVar `_S`
+    |
+183 |     @classmethod
+184 |     def bad_class_method_with_string_annotations(cls: "type[_S]") -> "_S": ... # PYI019
+    |                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^ PYI019
+    |
+    = help: Replace TypeVar `_S` with `Self`
+
+ℹ Safe fix
+181 181 |     def bad_instance_method_with_string_annotations(self: "_S", arg: str) -> "_S": ... # PYI019
+182 182 | 
+183 183 |     @classmethod
+184     |-    def bad_class_method_with_string_annotations(cls: "type[_S]") -> "_S": ... # PYI019
+    184 |+    def bad_class_method_with_string_annotations(cls) -> "Self": ... # PYI019
+185 185 | 
+186 186 | 
+187 187 |     @classmethod
+
+PYI019_0.pyi:188:50: PYI019 [*] Use `Self` instead of custom TypeVar `_S`
+    |
+187 |     @classmethod
+188 |     def bad_class_method_with_mixed_annotations_1(cls: "type[_S]") -> _S: ... # PYI019
+    |                                                  ^^^^^^^^^^^^^^^^^^^^^^^ PYI019
+    |
+    = help: Replace TypeVar `_S` with `Self`
+
+ℹ Safe fix
+185 185 | 
+186 186 | 
+187 187 |     @classmethod
+188     |-    def bad_class_method_with_mixed_annotations_1(cls: "type[_S]") -> _S: ... # PYI019
+    188 |+    def bad_class_method_with_mixed_annotations_1(cls) -> Self: ... # PYI019
+189 189 | 
+190 190 | 
+191 191 |     @classmethod
+
+PYI019_0.pyi:192:50: PYI019 [*] Use `Self` instead of custom TypeVar `_S`
+    |
+191 |     @classmethod
+192 |     def bad_class_method_with_mixed_annotations_1(cls: type[_S]) -> "_S": ... # PYI019
+    |                                                  ^^^^^^^^^^^^^^^^^^^^^^^ PYI019
+    |
+    = help: Replace TypeVar `_S` with `Self`
+
+ℹ Safe fix
+189 189 | 
+190 190 | 
+191 191 |     @classmethod
+192     |-    def bad_class_method_with_mixed_annotations_1(cls: type[_S]) -> "_S": ... # PYI019
+    192 |+    def bad_class_method_with_mixed_annotations_1(cls) -> "Self": ... # PYI019
+193 193 | 
+194 194 | 
+195 195 | class BadSubscriptReturnTypeWithStringTypeHints:
+
+PYI019_0.pyi:197:10: PYI019 [*] Use `Self` instead of custom TypeVar `S`
+    |
+195 | class BadSubscriptReturnTypeWithStringTypeHints:
+196 |     @classmethod
+197 |     def m[S](cls: "type[S]") -> "type[S]": ...  # PYI019
+    |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PYI019
+    |
+    = help: Replace TypeVar `S` with `Self`
+
+ℹ Safe fix
+194 194 | 
+195 195 | class BadSubscriptReturnTypeWithStringTypeHints:
+196 196 |     @classmethod
+197     |-    def m[S](cls: "type[S]") -> "type[S]": ...  # PYI019
+    197 |+    def m(cls) -> "type[Self]": ...  # PYI019
+198 198 | 
+199 199 | 
+200 200 | class GoodClassWithStringTypeHints: