[issue43006] Changed behaviour of inspect.signature() in Python 3.10

[Zac Hatfield-Dodds]

New submission from Zac Hatfield-Dodds <zac.hatfield.dodds at gmail.com>:

Consider the following snippet, which passes on Python 3.9 and earlier:


    import inspect

    def f(x: int = None):
        pass

    print(inspect.signature(constructor))
    assert inspect.signature(constructor).parameters["a"].annotation == int


But under Python 3.10 (alpha 4), the annotation is instead read as Optional[int].  This is correct for typing.get_type_hints(), but *not* for inspect.signature().

I therefore suspect that this is an accidental side-effect from support for PEP-563 deferred evaluation of annotations.

----------
components: Library (Lib)
messages: 385524
nosy: Zac Hatfield-Dodds
priority: normal
severity: normal
status: open
title: Changed behaviour of inspect.signature() in Python 3.10
versions: Python 3.10

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue43006>
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