CO_FUTURE_ANNOTATIONS flag is not documented or in inspect

[f9e7a2ee-b641-456a-a5a2-df4439a7109f]

BPO	45805
Nosy	@brettcannon, @benjaminp, @merwok, @markshannon, @1st1, @saulshanabrook, @pablogsal, @isidentical

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GitHub fields: ```python assignee = None closed_at = None created_at = labels = ['3.11', 'library', 'docs'] title = 'CO_FUTURE_ANNOTATIONS flag is not documented or in inspect' updated_at = user = 'https://github.com/saulshanabrook' ``` bugs.python.org fields: ```python activity = actor = 'eric.araujo' assignee = 'docs@python' closed = False closed_date = None closer = None components = ['Documentation', 'Library (Lib)'] creation = creator = 'saulshanabrook' dependencies = [] files = [] hgrepos = [] issue_num = 45805 keywords = [] message_count = 6.0 messages = ['406309', '406310', '406311', '406621', '406622', '406732'] nosy_count = 9.0 nosy_names = ['brett.cannon', 'benjamin.peterson', 'eric.araujo', 'docs@python', 'Mark.Shannon', 'yselivanov', 'saulshanabrook', 'pablogsal', 'BTaskaya'] pr_nums = [] priority = 'normal' resolution = None stage = None status = 'open' superseder = None type = None url = 'https://bugs.python.org/issue45805' versions = ['Python 3.11'] ```

[f9e7a2ee-b641-456a-a5a2-df4439a7109f]

The CO_FUTURE_ANNOTATIONS code flag was added in Python 3.7 I believe in this PR https://github.com/python/cpython/pull/4390.

However, it does not appear in dis's COMPILER_FLAG_NAMES map and so is not documented in inspect or pretty printed.

I believe the fix would be to add it to the dict in dis as well as document it in inspect.

[f9e7a2ee-b641-456a-a5a2-df4439a7109f]

I am closing this because, I realized I was unclear on whether the future flags end up as code flags. I thought we were just missing this one, but then realized that none of the other future flags are documented either.

I had found a flag that was not recognized, 0x1000000, and for some reason thought it was related to the future annotations import.

[f9e7a2ee-b641-456a-a5a2-df4439a7109f]

Actually, keeping this open.

I am still unclear if this is expected behavior or not, but I do notice that the dis module is unable to read the flag when the annotations future is imported.

For example dis.pretty_flags(compile("from __future__ import annotations", "", "exec").co_flags) return 'NOFREE, 0x1000000'.

Sorry for the repeated messages.

[merwok]

No worry about posting multiple messages.

I think the flag is documented through the __future__ module. Future imports are both special-cased by the compiler to enable custom behaviour, but also real, regular imports!

    >>> from __future__ import annotations
    >>> annotations
    _Feature((3, 7, 0, 'beta', 1), (3, 10, 0, 'alpha', 0), 16777216)
    >>> hex(annotations.compiler_flag)
    '0x1000000'

[f9e7a2ee-b641-456a-a5a2-df4439a7109f]

Thanks Éric!

Do you think it would make sense to add the future flags as well to the inspect flags documentation (https://docs.python.org/3/library/inspect.html#code-objects-bit-flags) and to the dis.pretty_flags?

[merwok]

I am not sure. Adding compiler people to the nosy list!