Beets: ImportError: cannot import name 'NoReturn'

[DarkVirtue]

Problem

Any invocation of beet immediately fails. This was working as recently as three weeks ago.

Running this command in verbose (-vv) mode:

$ beet -vv import Amaranthe
Traceback (most recent call last):
  File "/usr/local/bin/beet", line 7, in <module>
    from beets.ui import main
  File "/usr/local/lib/python3.5/dist-packages/beets/ui/__init__.py", line 42, in <module>
    from beets.autotag import mb
  File "/usr/local/lib/python3.5/dist-packages/beets/autotag/__init__.py", line 26, in <module>
    from .match import tag_item, tag_album, Proposal  # noqa
  File "/usr/local/lib/python3.5/dist-packages/beets/autotag/match.py", line 24, in <module>
    from munkres import Munkres
  File "/usr/local/lib/python3.5/dist-packages/munkres.py", line 20, in <module>
    from typing import Union, NewType, Sequence, Tuple, NoReturn, Optional, Callable
ImportError: cannot import name 'NoReturn'

Setup

• OS: Debian 9
• Python version: 3.5.3
• beets version: 1.4.7 (I think; beet --version fails with the above error)
• Turning off plugins made problem go away (yes/no): no

My configuration (output of beet config) is:

directory: /home/media/music
library: /var/lib/beets/data/musiclibrary.db
plugins: fetchart lyrics lastgenre multidisc missing scrub
import:
  move: yes
  language: en
paths:
  default: $albumartist_sort - $album ($year)/%if{$multidisc,Disc $disc%if{$disctitle, - $disctitle}/}/$track - $title
asciify_paths: yes
missing:
  format: $albumartist_sort - $album ($year)/%if{$multidisc,Disc $disc%if{$disctitle, - $disctitle}/}/$track - $title
  count: no
  total: no

[ethanrjones97]

Seconding this bug report.

Traceback (most recent call last):
  File "/home/erj/.local/bin/beet", line 7, in <module>
    from beets.ui import main
  File "/home/erj/.local/lib/python3.5/site-packages/beets/ui/__init__.py", line 42, in <module>
    from beets.autotag import mb
  File "/home/erj/.local/lib/python3.5/site-packages/beets/autotag/__init__.py", line 26, in <module>
    from .match import tag_item, tag_album, Proposal  # noqa
  File "/home/erj/.local/lib/python3.5/site-packages/beets/autotag/match.py", line 24, in <module>
    from munkres import Munkres
  File "/home/erj/.local/lib/python3.5/site-packages/munkres.py", line 20, in <module>
    from typing import Union, NewType, Sequence, Tuple, NoReturn, Optional, Callable
ImportError: cannot import name 'NoReturn'

Setup

• OS: Trisquel 8
• Python version: 3.5.2
• beets version: 1.4.7 - freshly installed from pip3
• Turning off plugins made problem go away (yes/no): no

Config

directory: ~/Muisc
library: ~/.config/beets/musiclibrary.db
plugins: fetchart lyrics badfiles scrub zero duplicates missing
zero:
    fields: comments images acoustid_fingerprint
    update_database: true

However, my other machine does not have this error:

Setup

• OS: Ubuntu 18.04
• Python version: 3.6.7
• beets version: 1.4.7 - freshly upgraded with pip3

My guess is a recent library update broke Python 3.5.x support.

[jackwilsdon]

It seems that munkres has changed it's minimum Python version - their changelog says that it still supports 3.5, however the typings they've added require 3.6.5 (typing.NoReturn was only introduced in Python 3.6.5).

@sampsyo any suggestions? We could lock down the version of this to pre-1.1.0, but it might be better if we open up an issue or PR on munkres to fix this in the long term.

[sampsyo]

Yep! That sounds like exactly what's going on, @jackwilsdon. Thanks for looking into it.

I recommend we do both: pin the version for now, and also file an issue to tell the Munkres developers that their requirements don't align with the code.

[jackwilsdon]

After doing a little bit more digging, it seems it was actually added in Python 3.5.4 and the Python docs are wrong! This is still less than ideal, so I'm opening a PR on munkres to remove uses of typing.NoReturn until they drop support for <3.5.4.

[sampsyo]

Fantastic! Thank you for digging into the issue. :sparkles:

[jackwilsdon]

munkres 1.1.2 has been released with a fix for <3.5.4.

@DarkVirtue @ethanrjones97 could you try pip install -U beets? It should update the version of munkres installed.

If that doesn't work try pip install munkres==1.1.2, but you shouldn't need to do that as updating beets should sort it out for you.

[DarkVirtue]

Pip grabbed the new version of munkres and beets is working fine for me now.

Thanks a ton!

[sampsyo]

Wow; that was quick!! Thanks for the fast work, @jackwilsdon!