Make slice generic (#11637)

Author: Sachaa-Thanasius

stdlib/builtins.pyi

@@ -9,6 +9,7 @@ from _typeshed import (
     ConvertibleToFloat,
     ConvertibleToInt,
     FileDescriptorOrPath,
+    MaybeNone,
     OpenBinaryMode,
     OpenBinaryModeReading,
     OpenBinaryModeUpdating,
@@ -94,6 +95,9 @@ _SupportsAnextT = TypeVar("_SupportsAnextT", bound=SupportsAnext[Any], covariant
 _AwaitableT = TypeVar("_AwaitableT", bound=Awaitable[Any])
 _AwaitableT_co = TypeVar("_AwaitableT_co", bound=Awaitable[Any], covariant=True)
 _P = ParamSpec("_P")
+_StartT = TypeVar("_StartT", covariant=True, default=Any)
+_StopT = TypeVar("_StopT", covariant=True, default=Any)
+_StepT = TypeVar("_StepT", covariant=True, default=Any)
 
 class object:
     __doc__: str | None
@@ -936,17 +940,25 @@ class bool(int):
     def __invert__(self) -> int: ...
 
 @final
-class slice:
+class slice(Generic[_StartT, _StopT, _StepT]):
     @property
-    def start(self) -> Any: ...
+    def start(self) -> _StartT: ...
     @property
-    def step(self) -> Any: ...
+    def step(self) -> _StepT: ...
     @property
-    def stop(self) -> Any: ...
+    def stop(self) -> _StopT: ...
     @overload
-    def __new__(cls, stop: Any, /) -> Self: ...
+    def __new__(cls, stop: int | None) -> slice[int | MaybeNone, int | MaybeNone, int | MaybeNone]: ...
     @overload
-    def __new__(cls, start: Any, stop: Any, step: Any = ..., /) -> Self: ...
+    def __new__(
+        cls, start: int | None, stop: int | None, step: int | None = None
+    ) -> slice[int | MaybeNone, int | MaybeNone, int | MaybeNone]: ...
+    @overload
+    def __new__(cls, stop: _T2, /) -> slice[Any, _T2, Any]: ...
+    @overload
+    def __new__(cls, start: _T1, stop: _T2, /) -> slice[_T1, _T2, Any]: ...
+    @overload
+    def __new__(cls, start: _T1, stop: _T2, step: _T3, /) -> slice[_T1, _T2, _T3]: ...
     def __eq__(self, value: object, /) -> bool: ...
     if sys.version_info >= (3, 12):
         def __hash__(self) -> int: ...