cpython/Misc/NEWS.d/next/Library/2023-03-18-14-59-21.gh-issu...

typing: Fix a bug relating to substitution in custom classes generic over a
:class:`~typing.ParamSpec`. Previously, if the ``ParamSpec`` was substituted
with a parameters list that itself contained a :class:`~typing.TypeVar`, the
``TypeVar`` in the parameters list could not be subsequently substituted. This
is now fixed.

Patch by Nikita Sobolev.
gh-88965: typing: fix type substitution of a list of types after initial `ParamSpec` substitution (#102808) Previously, this used to fail: ```py from typing import * T = TypeVar("T") P = ParamSpec("P") class X(Generic[P]): f: Callable[P, int] Y = X[[int, T]] Z = Y[str] ``` Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com> 2023-03-23 16:26:11 +00:00			`typing: Fix a bug relating to substitution in custom classes generic over a`
			:class:`~typing.ParamSpec`. Previously, if the ``ParamSpec`` was substituted
			with a parameters list that itself contained a :class:`~typing.TypeVar`, the
			``TypeVar`` in the parameters list could not be subsequently substituted. This
			`is now fixed.`

			`Patch by Nikita Sobolev.`