Message 412149 - Python tracker

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Author	kj
Recipients	gvanrossum, kj, posita, sobolevn
Date	2022-01-30.14:44:34
SpamBayes Score	-1.0
Marked as misclassified	Yes
Message-id	<[email protected]>
In-reply-to

Content
Wow! Thanks, that's an interesting find. My hunch is that we should be passing in _typevar_types and _paramspec_tvars in the copy_with of _GenericAlias and _ConcatenateGenericAlias. Inconsistent copy_with could trigger subtle bugs in ForwardRefs and get_type_hints. I can reproduce a semi-bug right now: >>> P = ParamSpec('P') >>> Callable[P, int].__parameters__ (~P,) >>> Callable[P, int].copy_with((P,int)) typing.Callable[~P, int] >>> Callable[P, int].copy_with((P,int)).__parameters__ () ^ This shouldn't be empty!! Would you like to submit a patch for this?

Wow! Thanks, that's an interesting find. My hunch is that we should be passing in _typevar_types and _paramspec_tvars in the copy_with of _GenericAlias and _ConcatenateGenericAlias. Inconsistent copy_with could trigger subtle bugs in ForwardRefs and get_type_hints. I can reproduce a semi-bug right now:

>>> P = ParamSpec('P')
>>> Callable[P, int].__parameters__
(~P,)
>>> Callable[P, int].copy_with((P,int))
typing.Callable[~P, int]
>>> Callable[P, int].copy_with((P,int)).__parameters__
()
^ This shouldn't be empty!!

Would you like to submit a patch for this?

History
Date	User	Action	Args
2022-01-30 14:44:34	kj	set	recipients: + kj, gvanrossum, posita, sobolevn
2022-01-30 14:44:34	kj	set	messageid: <[email protected]>
2022-01-30 14:44:34	kj	link	issue46581 messages
2022-01-30 14:44:34	kj	create