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Type substitution in generic aliases does not work if ParamSpec is followed by TypeVarTuple #99379
Description
The following code:
from typing import *
P = ParamSpec('P')
Ts = TypeVarTuple('Ts')
C = Callable[P, Tuple[*Ts]]
C[[int], str, bytes]gives an error:
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/serhiy/py/cpython3.11/Lib/typing.py", line 363, in inner
return func(*args, **kwds)
^^^^^^^^^^^^^^^^^^^
File "/home/serhiy/py/cpython3.11/Lib/typing.py", line 1393, in __getitem__
new_args = self._determine_new_args(args)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/serhiy/py/cpython3.11/Lib/typing.py", line 1417, in _determine_new_args
args = prepare(self, args)
^^^^^^^^^^^^^^^^^^^
File "/home/serhiy/py/cpython3.11/Lib/typing.py", line 1229, in __typing_prepare_subst__
return _prepare_paramspec_params(alias, args)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/serhiy/py/cpython3.11/Lib/typing.py", line 297, in _prepare_paramspec_params
_check_generic(cls, params, len(cls.__parameters__))
File "/home/serhiy/py/cpython3.11/Lib/typing.py", line 274, in _check_generic
raise TypeError(f"Too {'many' if alen > elen else 'few'} arguments for {cls};"
TypeError: Too many arguments for typing.Callable[~P, typing.Tuple[*Ts]]; actual 3, expected 2
The same for the C implementation (types.GenericAlias):
import collections.abc
C = collections.abc.Callable[P, Tuple[*Ts]]
C[[int], str, bytes]Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/serhiy/py/cpython3.11/Lib/_collections_abc.py", line 468, in __getitem__
new_args = super().__getitem__(item).__args__
^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/serhiy/py/cpython3.11/Lib/typing.py", line 1229, in __typing_prepare_subst__
return _prepare_paramspec_params(alias, args)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/serhiy/py/cpython3.11/Lib/typing.py", line 297, in _prepare_paramspec_params
_check_generic(cls, params, len(cls.__parameters__))
File "/home/serhiy/py/cpython3.11/Lib/typing.py", line 274, in _check_generic
raise TypeError(f"Too {'many' if alen > elen else 'few'} arguments for {cls};"
TypeError: Too many arguments for collections.abc.Callable[~P, typing.Tuple[*Ts]]; actual 3, expected 2
And for user generics:
T = TypeVar('T')
class A(Generic[P, T]):
pass
B = A[P, Tuple[*Ts]]
B[[int], str, bytes]Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/serhiy/py/cpython3.11/Lib/typing.py", line 363, in inner
return func(*args, **kwds)
^^^^^^^^^^^^^^^^^^^
File "/home/serhiy/py/cpython3.11/Lib/typing.py", line 1393, in __getitem__
new_args = self._determine_new_args(args)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/serhiy/py/cpython3.11/Lib/typing.py", line 1417, in _determine_new_args
args = prepare(self, args)
^^^^^^^^^^^^^^^^^^^
File "/home/serhiy/py/cpython3.11/Lib/typing.py", line 1229, in __typing_prepare_subst__
return _prepare_paramspec_params(alias, args)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/serhiy/py/cpython3.11/Lib/typing.py", line 297, in _prepare_paramspec_params
_check_generic(cls, params, len(cls.__parameters__))
File "/home/serhiy/py/cpython3.11/Lib/typing.py", line 274, in _check_generic
raise TypeError(f"Too {'many' if alen > elen else 'few'} arguments for {cls};"
TypeError: Too many arguments for __main__.A[~P, typing.Tuple[*Ts]]; actual 3, expected 2
But it works if ParamSpec and TypeVarTuple are in different order:
class A(Generic[T, P]):
pass
B = A[Tuple[*Ts], P]
B[str, bytes, [int]]It is a different bug than #99344 because it happens when you substitute in a generic alias instead of a user generic.
Activity
pythongh-99344, pythongh-99379, pythongh-99382: Fix issues in substit…
gh-99344, gh-99379, gh-99382: Fix issues in substitution of ParamSpec…
pythongh-99344, pythongh-99379, pythongh-99382: Fix issues in substit…
pythongh-99344, pythongh-99379, pythongh-99382: Fix issues in substit…
gh-99344, gh-99379, gh-99382: Fix issues in substitution of ParamSpec…
AlexWaygood commentedon Apr 10, 2023
These examples all work fine on
mainand on 3.11.2. It looks like they were fixed by #99412, and appropriate tests were added. Is there anything more to do here?AlexWaygood commentedon May 20, 2023
Closing as "completed", since this was buggy in the past, but the bug was fixed