[New-bugs-announce] [issue35834] get_type_hints exposes an instance of ForwardRef (internal class) in its result, with `from __future__ import annotations` enabled

[Lincoln Quirk]

New submission from Lincoln Quirk <lincoln at wave.com>:

Consider this code:

```
from __future__ import annotations

import typing

class A:
    f: 'Undef'

hints = typing.get_type_hints(A)
```

Since Undef is not defined, I should get an exception when calling get_type_hints, something like "NameError: name 'Undef' is not defined". But instead, get_type_hints returns {'f': ForwardRef('Undef')}.

If I remove the `from __future__ import annotations` line, get_type_hints correctly raises this exception.

I think the behavior should be to raise an exception in both cases.

----------
messages: 334396
nosy: Lincoln Quirk
priority: normal
severity: normal
status: open
title: get_type_hints exposes an instance of ForwardRef (internal class) in its result, with `from __future__ import annotations` enabled
type: behavior
versions: Python 3.7, Python 3.8

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue35834>
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