annotationlib - evaluating forward references in STRING format can 'leak' internal names

[DavidCEllis]

Bug report

Bug description:

If a ForwardRef object needs internal names to store values of known objects these internal names currently replace the type_repr of the objects they represent when the ForwardRef is evaluated as Format.STRING or when looking at the repr.

If it was just the repr I'd probably put this as a feature request but as it makes the STRING format arguably 'wrong' I think it should be considered a bug.

from annotationlib import get_annotations, Format

class Example:
    a: ref | str

ann = get_annotations(Example, format=Format.FORWARDREF)['a']
print(ann)
print(ann.evaluate(format=Format.STRING))

On 3.14 or Main:

ForwardRef('ref | __annotationlib_name_1__', is_class=True, owner=<class '__main__.Example'>)
ref | __annotationlib_name_1__

Expected:

ForwardRef('ref | str', is_class=True, owner=<class '__main__.Example'>)
ref | str

CPython versions tested on:

3.14, CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-148680: Replace internal names with type_reprs of objects in string representations of ForwardRef #148682