support for asymmetric __replace__ in copy.replace

Author: jorenham

stdlib/copy.pyi

@@ -1,16 +1,17 @@
 import sys
 from typing import Any, Protocol, TypeVar, type_check_only
-from typing_extensions import Self
+from typing_extensions import ParamSpec
 
 __all__ = ["Error", "copy", "deepcopy"]
 
 _T = TypeVar("_T")
-_SR = TypeVar("_SR", bound=_SupportsReplace)
+_Tss = ParamSpec("_Tss")
+_RT_co = TypeVar("_RT_co", covariant=True)
 
 @type_check_only
-class _SupportsReplace(Protocol):
-    # Usually there are *some* kwargs, but there's no great way to express this.
-    def __replace__(self, /) -> Self: ...
+class _SupportsReplace(Protocol[_Tss, _RT_co]):
+    # In reality doesn't support args, but there's no other great way to express this.
+    def __replace__(self, /, *_: _Tss.args, **changes: _Tss.kwargs) -> _RT_co: ...
 
 # None in CPython but non-None in Jython
 PyStringMap: Any
@@ -21,7 +22,7 @@ def copy(x: _T) -> _T: ...
 
 if sys.version_info >= (3, 13):
     __all__ += ["replace"]
-    def replace(obj: _SR, /, **changes: Any) -> _SR: ...
+    def replace(obj: _SupportsReplace[..., _RT_co], /, **changes: Any) -> _RT_co: ...
 
 class Error(Exception): ...