inspect.signature crashes with NameError for TYPE_CHECKING-only annotations

Bug report

Bug description:

if typing.TYPE_CHECKING:
    from somelib import SomeType

def f(arg: SomeType): ...

inspect.signature(f)  # NameError: name 'SomeType' is not defined

Some linters have rules that move imports into TYPE_CHECKING blocks and after this seemingly benign change inspect.signature will unexpectedly fail, even if its caller never cared about annotations.

At the very least, the documentation of inspect.signature should warn about this (currently it only talks about string annotations and makes no mention of Python 3.14 lazy annotations). But perhaps there’s a way of making inspect.signature work without such a surprising behavior, maybe by making some Signature fields lazy.

CPython versions tested on:

3.14

Operating systems tested on:

Linux

Linked PRs

• gh-153055

Beginne mit dem Einstiegspunkt inspect.signature und dem im Bericht beschriebenen Verhalten verzögerter Annotationen in Python 3.14. Prüfe den verknüpften PR gh-153055, bevor du bestimmst, ob der akzeptierte Umfang Dokumentation oder eine Verhaltensänderung ist; das Issue definiert keine einzelne Abschlussbedingung.