Support most use cases for PEP 612 with Generic

[Fidget-Spinner]

Support PEP 612 and most user-defined generics use cases. This also brings the PEP 612 test suite to near parity with CPython. Note some limitations in valid use cases below simply because of runtime limitations.

Fixes #816.

[JelleZijlstra]

Thanks! Looks good but let's see what CI says. When I tried this locally on 3.6 it failed with AttributeError: 'ParamSpec' object has no attribute '_get_type_vars'., so we may have to add that method.

[Fidget-Spinner]

Thanks! Looks good but let's see what CI says. When I tried this locally on 3.6 it failed with AttributeError: 'ParamSpec' object has no attribute '_get_type_vars'., so we may have to add that method.

Thanks for testing. I managed to get it working locally in 3.6 after much spelunking (wow, typing was so different back then).

I don't think I can get the runtime __args__ tests to pass with 3.5.2. Here's a copy from the CI:

=================================== FAILURES ===================================
________________________ ParamSpecTests.test_valid_uses ________________________
self = <test_typing_extensions.ParamSpecTests testMethod=test_valid_uses>
    def test_valid_uses(self):
        P = ParamSpec('P')
        T = TypeVar('T')
        C1 = typing.Callable[P, int]
>       self.assertEqual(C1.__args__, (P, int))
E       AssertionError: Tuples differ: (~P,) != (~P, <class 'int'>)
E       
E       Second tuple contains 1 additional elements.
E       First extra element 1:
E       <class 'int'>
E       
E       - (~P,)
E       + (~P, <class 'int'>)
typing_extensions/src_py3/test_typing_extensions.py:2015: AssertionError

Callable in 3.5.2 looks a little strange. Is this a bug in 3.5.2 or am I missing something here?
https://github.com/python/cpython/blob/91185fe0284a04162e0b3425b53be49bdbfad67d/Lib/typing.py#L762

Other than that, all other versions pass. I'm tempted to just drop 3.5.2 as it's already EOL anyways.

[gvanrossum]

Since 3.5 is long past its end of life (why can't we say it's "dead"? :-) I think you shouldn't spend more time trying to figure this out, just disable that test for 3.5.

…

On Fri, Jun 11, 2021 at 9:05 AM Ken Jin ***@***.***> wrote: Thanks! Looks good but let's see what CI says. When I tried this locally on 3.6 it failed with AttributeError: 'ParamSpec' object has no attribute '_get_type_vars'., so we may have to add that method. Thanks for testing. I managed to get it working locally in 3.6 after much spelunking (wow, typing was so different back then). I don't think I can get the runtime __args__ tests to pass with 3.5.2. Here's a copy from the CI: =================================== FAILURES =================================== ________________________ ParamSpecTests.test_valid_uses ________________________ self = <test_typing_extensions.ParamSpecTests testMethod=test_valid_uses> def test_valid_uses(self): P = ParamSpec('P') T = TypeVar('T') C1 = typing.Callable[P, int] > self.assertEqual(C1.__args__, (P, int)) E AssertionError: Tuples differ: (~P,) != (~P, <class 'int'>) E E Second tuple contains 1 additional elements. E First extra element 1: E <class 'int'> E E - (~P,) E + (~P, <class 'int'>) typing_extensions/src_py3/test_typing_extensions.py:2015: AssertionError Callable in 3.5.2 looks a little strange. Is this a bug in 3.5.2 or am I missing something here? https://github.com/python/cpython/blob/91185fe0284a04162e0b3425b53be49bdbfad67d/Lib/typing.py#L762 — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#817 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAWCWMQP24COIJRO2OCVYNLTSIX3VANCNFSM46Q2G6PA> .

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[JelleZijlstra]

Thank you!

[jaraco]

This change appears implicated in #865.