New submission from Serhiy Storchaka <storchaka+cpyt...@gmail.com>:
If the user generic with ParamSpec parameter substituted with a parametrised
list containing TypeVar, that TypeVar cannot be substituted.
>>> from typing import *
>>> T = TypeVar("T")
>>> P = ParamSpec("P")
>>> class X(Generic[P]):
... f: Callable[P, int]
...
>>> Y = X[[int, T]]
>>> Y
__main__.X[(<class 'int'>, ~T)]
>>> Y[str]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/serhiy/py/cpython/Lib/typing.py", line 309, in inner
return func(*args, **kwds)
^^^^^^^^^^^^^^^^^^^
File "/home/serhiy/py/cpython/Lib/typing.py", line 1028, in __getitem__
_check_generic(self, params, len(self.__parameters__))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/serhiy/py/cpython/Lib/typing.py", line 228, in _check_generic
raise TypeError(f"{cls} is not a generic class")
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: __main__.X[(<class 'int'>, ~T)] is not a generic class
Expected result equal to X[[int, str]].
----------
components: Library (Lib)
messages: 398694
nosy: gvanrossum, kj, serhiy.storchaka
priority: normal
severity: normal
status: open
title: Substitution does not work after ParamSpec substitution of the user
generic with a list of TypeVars
type: behavior
versions: Python 3.10, Python 3.11
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue44802>
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