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type not generic when running with Python < 3.9 #10303

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#10766
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type not generic when running with Python < 3.9#10303
#10766
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bugmypy got something wrong

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@srittau
srittau
opened on Apr 9, 2021

Bug Report

Please consider the following stub file:

x: dict[str, str]
y: type[str]

When checking it with mypy 0.820+dev.1e96f1df48a6e06ba598fa8230b96671b206cba0 and Python 3.9.4, it passes. Using Python 3.8.9 on the other hand, produces the following output:

foo.pyi:2: error: "type" expects no type arguments, but 1 given

It's weird that generic dict works, but generic type doesn't. (Although I'd expect both to work with any Python version.)

This came up during python/typeshed#5192.

Activity

  1. srittau
    added
    bugmypy got something wrong
    on Apr 9, 2021
  2. JukkaL
    closed this as completedin #10766on Jul 5, 2021
  3. JukkaL
    added a commit that references this issue on Jul 5, 2021

    Fixes to generic builtin types (#10766)

    6eafc5e

  4. srittau commented on Dec 22, 2021

    @srittau
    srittau
    on Dec 22, 2021
    ContributorAuthor

    @JukkaL This doesn't seem to fixed in mypy 0.930:

    $ mypy --version
mypy 0.930
$ cat foo.pyi 
x: dict[str, str]
y: type[str]
$ mypy --python-version=3.9 foo.pyi 
Success: no issues found in 1 source file
$ mypy --python-version=3.8 foo.pyi 
foo.pyi:2: error: "type" expects no type arguments, but 1 given
Found 1 error in 1 file (checked 1 source file)

    (I tested it with both Python 3.9.6 and 3.6.14.)

  5. AlexWaygood commented on Dec 28, 2021

    @AlexWaygood
    AlexWaygood
    on Dec 28, 2021
    Member

    @JukkaL This doesn't seem to fixed in mypy 0.930:

    Interestingly, it appears to be fixed for .py files, but not for .pyi files. This, in a .py file, will pass using Python 3.7:

    from __future__ import annotations
foo: type[str]

    But this, in a .pyi file, fails using Python <= 3.8:

    foo: type[str]

    Many similar errors can be found in the CI output for python/typeshed#6681.

  6. AlexWaygood commented on Dec 28, 2021

    @AlexWaygood
    AlexWaygood
    on Dec 28, 2021
    Member

    Cc. @sobolevn

  7. sobolevn commented on Dec 29, 2021

    @sobolevn
    sobolevn
    on Dec 29, 2021
    Member

    Sorry, I cannot not reopen issues, but here's my PR: #11863

  8. hauntsaninja commented on Jan 6, 2022

    @hauntsaninja
    hauntsaninja
    on Jan 6, 2022
    Collaborator

    Thanks to sobolevn this should be fixed for pyi with old Pythons!

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