Add special-casing for __match_args__ fields

CHANGELOG.md

@@ -1,5 +1,13 @@
 # Change Log
 
+## Unreleased
+
+Behaviour changes:
+* Add special-casing so that string literals are allowed in the context of
+  `__match_args__` assignments inside a class definition.
+* Add special-casing so that arbitrary values can be assigned to a variable in
+  a stub file if the variable is annotated with `Final`.
+
 ## 22.2.0
 
 Bugfixes:

pyi.py

@@ -301,6 +301,7 @@ def _is_object(node: ast.expr, name: str, *, from_: Container[str]) -> bool:
 _is_Any = partial(_is_object, name="Any", from_={"typing"})
 _is_overload = partial(_is_object, name="overload", from_={"typing"})
 _is_final = partial(_is_object, name="final", from_=_TYPING_MODULES)
+_is_Final = partial(_is_object, name="Final", from_=_TYPING_MODULES)
 _is_Self = partial(_is_object, name="Self", from_=({"_typeshed"} | _TYPING_MODULES))
 
 
@@ -622,7 +623,10 @@ def visit_Assign(self, node: ast.Assign) -> None:
         else:
             self.error(node, Y017)
             target_name = None
-        if target_name == "__all__":
+        is_special_assignment = (
+            target_name == "__match_args__" and self.in_class.active
+        ) or (target_name == "__all__" and not self.in_class.active)
+        if is_special_assignment:
             with self.string_literals_allowed.enabled():
                 self.generic_visit(node)
         else:
@@ -648,7 +652,7 @@ def visit_Assign(self, node: ast.Assign) -> None:
         # We avoid triggering Y026 for calls and = ... because there are various
         # unusual cases where assignment to the result of a call is legitimate
         # in stubs.
-        if target_name != "__all__" and not isinstance(
+        if not is_special_assignment and not isinstance(
             assignment, (ast.Ellipsis, ast.Call)
         ):
             self.error(node, Y026)
@@ -694,6 +698,10 @@ def visit_Expr(self, node: ast.Expr) -> None:
             self.generic_visit(node)
 
     def visit_AnnAssign(self, node: ast.AnnAssign) -> None:
+        if _is_Final(node.annotation):
+            with self.string_literals_allowed.enabled():
+                self.generic_visit(node)
+            return
         if _is_name(node.target, "__all__") and not self.in_class.active:
             with self.string_literals_allowed.enabled():
                 self.generic_visit(node)

tests/attribute_annotations.pyi

@@ -1,4 +1,7 @@
-from typing import TypeAlias
+import typing
+from typing import Final, TypeAlias
+
+import typing_extensions
 
 field1: int
 field2: int = ...
@@ -13,6 +16,15 @@ field8 = False  # Y015 Bad default value. Use "field8 = ..." instead of "field8
 field9 = None    # Y026 Use typing_extensions.TypeAlias for type aliases
 field10: TypeAlias = None
 
+# Tests for Final
+field11: Final = 1
+field12: Final = "foo"
+field13: Final = b"foo"
+field14: Final = True
+field15: Final = ('a', 'b', 'c')
+field16: typing.Final = "foo"
+field17: typing_extensions.Final = "foo"
+
 class Foo:
     field1: int
     field2: int = ...
@@ -22,3 +34,11 @@ class Foo:
     field6 = 0  # Y015 Bad default value. Use "field6 = ..." instead of "field6 = 0"
     field7 = b""  # Y015 Bad default value. Use "field7 = ..." instead of "field7 = b''"
     field8 = False  # Y015 Bad default value. Use "field8 = ..." instead of "field8 = False"
+    # Tests for Final
+    field9: Final = 1
+    field10: Final = "foo"
+    field11: Final = b"foo"
+    field12: Final = True
+    field13: Final = ('a', 'b', 'c')
+    field14: typing.Final = "foo"
+    field15: typing_extensions.Final = "foo"

tests/quotes.pyi

@@ -4,6 +4,7 @@ from typing import Annotated, Literal, TypeAlias, TypeVar
 import typing_extensions
 
 __all__ = ["f", "g"]
+__match_args__ = ('foo',)  # Y026 Use typing_extensions.TypeAlias for type aliases  # Y020 Quoted annotations should never be used in stubs
 
 def f(x: "int"): ...  # Y020 Quoted annotations should never be used in stubs
 def g(x: list["int"]): ...  # Y020 Quoted annotations should never be used in stubs
@@ -18,3 +19,5 @@ Alias: TypeAlias = list["int"]  # Y020 Quoted annotations should never be used i
 
 class Child(list["int"]):  # Y020 Quoted annotations should never be used in stubs
     """Documented and guaranteed useful."""  # Y021 Docstrings should not be included in stubs
+    __all__ = ('foo',)  # Y026 Use typing_extensions.TypeAlias for type aliases  # Y020 Quoted annotations should never be used in stubs
+    __match_args__ = ('foo', 'bar')