Backport many ParamSpec-related changes to Python 2 (#7054)

stdlib/@python2/pdb.pyi

@@ -2,8 +2,10 @@ from bdb import Bdb
 from cmd import Cmd
 from types import FrameType, TracebackType
 from typing import IO, Any, Callable, ClassVar, Iterable, Mapping, TypeVar
+from typing_extensions import ParamSpec
 
 _T = TypeVar("_T")
+_P = ParamSpec("_P")
 
 line_prefix: str  # undocumented
 
@@ -12,7 +14,7 @@ class Restart(Exception): ...
 def run(statement: str, globals: dict[str, Any] | None = ..., locals: Mapping[str, Any] | None = ...) -> None: ...
 def runeval(expression: str, globals: dict[str, Any] | None = ..., locals: Mapping[str, Any] | None = ...) -> Any: ...
 def runctx(statement: str, globals: dict[str, Any], locals: Mapping[str, Any]) -> None: ...
-def runcall(func: Callable[..., _T], *args: Any, **kwds: Any) -> _T | None: ...
+def runcall(func: Callable[_P, _T], *args: _P.args, **kwds: _P.kwargs) -> _T | None: ...
 def set_trace() -> None: ...
 def post_mortem(t: TracebackType | None = ...) -> None: ...
 def pm() -> None: ...