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get_type_hints + Final + future annotations = TypeError #890
Description
Opening for visibility. Issue on bugs.python.org: https://bugs.python.org/issue45166.
Feel free to close here or there 😄
Originally reported and investigated here: mkdocstrings/mkdocstrings#314
# final.py
from __future__ import annotations
from typing import Final, get_type_hints
name: Final[str] = "final"
class Class:
value: Final = 3000
get_type_hints(Class)Run python final.py, and you'll get this traceback:
Traceback (most recent call last):
File "final.py", line 11, in <module>
get_type_hints(Class)
File "/.../lib/python3.8/typing.py", line 1232, in get_type_hints
value = _eval_type(value, base_globals, localns)
File "/.../lib/python3.8/typing.py", line 270, in _eval_type
return t._evaluate(globalns, localns)
File "/.../lib/python3.8/typing.py", line 517, in _evaluate
self.__forward_value__ = _type_check(
File "/.../lib/python3.8/typing.py", line 145, in _type_check
raise TypeError(f"Plain {arg} is not valid as type argument")
TypeError: Plain typing.Final is not valid as type argumentNow comment the get_type_hints call, launch a Python interpreter, and enter these commands:
>>> import final
>>> from typing import get_type_hints
>>> get_type_hints(final)And you'll get this traceback:
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/.../lib/python3.9/typing.py", line 1449, in get_type_hints
value = _eval_type(value, globalns, localns)
File "/.../lib/python3.9/typing.py", line 283, in _eval_type
return t._evaluate(globalns, localns, recursive_guard)
File "/.../lib/python3.9/typing.py", line 538, in _evaluate
type_ =_type_check(
File "/.../lib/python3.9/typing.py", line 149, in _type_check
raise TypeError(f"{arg} is not valid as type argument")
TypeError: typing.Final[str] is not valid as type argumentI was able to replicate in 3.8, 3.9, 3.10 and 3.11. The annotations future is not available in 3.7 or lower.
Activity
hauntsaninja commented on Sep 10, 2021
Thanks, bpo is a good place for this :-)
pawamoy commented on Sep 10, 2021
Ha! That's what bpo means 😲
sobolevn commented on Sep 10, 2021
Let's see if this fixes your issue python/cpython#28279
pawamoy commented on Sep 10, 2021
Thanks @sobolevn! Nice to see you here 😄
pawamoy commented on Sep 26, 2021
@sobolevn's fix was merged and backported, I think we can close the issue 🙂
Thanks everyone!