class.__annotations__ gives weird value when using built-in type keywords as attribute

[Heerozh]

Bug report

Bug description:

class some:
    int    : int = 1
    normal : int = 1
some.__annotations__

returns:
{'int': 1, 'normal': 1}

class some:
    int_   : int = 1
    normal : int = 1
some.__annotations__

returns:
{'int_': int, 'normal': int}

CPython versions tested on:

3.11, 3.12

Operating systems tested on:

Linux, Windows

Linked PRs

• gh-122937: Add docs about annotations evaluation order #123060

[sobolevn]

This is how names and scopes work in Python.

int: int = 1 means:

• assign int as 1
• use name int as annotation
• which equals to 1, because you assigned it this way

Closing, since there were multiple issues about it and the anwser is always the same :)

[terryjreedy]

Should anything be added to the docs (I don't know where) to explain this better?

[AlexWaygood]

For reference, the previous issues where this has been raised are:

• __annotations__ lose type when a variable and its type have same name with default value None #121229
• Assigning to a class variable with name equal to annotation corrupts the annotations #108437
• Incorrect parsing of attribute with type annotation involving |, the attribute name having the same name as a class used in its type, and a default value #115844

It does seem to be coming up more and more regularly (for whatever reason), so if we can explain it better, that would be great... There's already documentation on this at https://docs.python.org/3/reference/simple_stmts.html#annassign, which is an appropriate place for this to be documented (since it's to do with core language semantics), but it's almost certainly not where beginners will think to look.

[sobolevn]

Maybe in https://docs.python.org/3/howto/annotations.html and link from dataclasses docs to there?

I would be happy to add this note!

[Heerozh]

I have also submitted issues to pycharm. If implemented, it should help others understand this in the future.

https://youtrack.jetbrains.com/issue/PY-75106/type-annotation-security-check-for-shadowing-name