Homebrew-core: Macvim python support is broken

[RobinClowers]

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• [x] ran brew update and can still reproduce the problem?
• [x] ran brew doctor, fixed all issues and can still reproduce the problem?
• [x] ran brew gist-logs <formula> (where <formula> is the name of the formula that failed) and included the output link?
• [x] if brew gist-logs didn't work: ran brew config and brew doctor and included their output with your issue?

$ brew gist-logs macvim
Error: No logs.

$ brew config
HOMEBREW_VERSION: 2.4.11
ORIGIN: https://github.com/Homebrew/brew
HEAD: 9ef993ab570ac6d4f2c4f88a96f2da8c3e71fa85
Last commit: 2 days ago
Core tap ORIGIN: https://github.com/Homebrew/homebrew-core
Core tap HEAD: a645bdd42e8b8703edfa27d7f69611dc263e17fa
Core tap last commit: 3 hours ago
Core tap branch: master
HOMEBREW_PREFIX: /usr/local
HOMEBREW_CASK_OPTS: []
HOMEBREW_EDITOR: mvim -v
HOMEBREW_MAKE_JOBS: 8
CPU: octa-core 64-bit kabylake
Homebrew Ruby: 2.6.3 => /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/ruby
Clang: 12.0 build 1200
Git: 2.28.0 => /usr/local/bin/git
Curl: 7.64.1 => /usr/bin/curl
Java: 1.8.0_242
macOS: 10.15.6-x86_64
CLT: 12.0.0.0.1.1595091463
Xcode: N/A

What you were trying to do (and why)

I upgraded macvim by running brew upgrade, and now it fails anytime it tries to import python modules.

What happened (include command output)

When I start vim, a plugin tries to load a python module, and I get this error:
E492: Not an editor command: from multiprocessing.resource_tracker import main;main(8)

What you expected to happen

I should be able to require python modules.

Step-by-step reproduction instructions (by running brew install commands)

brew install macvim
install a plugin that uses python (like https://github.com/Shougo/deoplete.nvim)
mvim -v

[SMillerDev]

What makes you think this is a problem with homebrew instead of Macvim?

[clason]

As a possibly useful data point: I have the same issue with vimR (the neovim fork of Macvim), where after the homebrew upgrade to Python 3.8 (without upgrading vimR), I get the same (or a similar, since neovim works slightly differently from vim in this regard) failure with Python plugins. vimR reports

  Checking /usr/local/bin/python3 caused an unknown error. (1, output: Fatal Python error: config_get_locale_encoding: failed to get the locale encoding: nl_langinfo(CODESET) failed
          Python runtime state: preinitialized

[RobinClowers]

@clason that sounds like it could be a problem with python itself? https://bugs.python.org/issue34544

[RobinClowers]

What makes you think this is a problem with homebrew instead of Macvim?

I guess I'm not sure, but it seems unlikely that macvim suddenly stop working with python. I downloaded the latest version of macvim from github (https://github.com/macvim-dev/macvim/releases/tag/snapshot-163) and it works fine with python 3.7. They are working on shipping a version that works with 3.8: https://github.com/macvim-dev/macvim/issues/1012, however it's apparently broken in a different way: https://github.com/macvim-dev/macvim/issues/1073.

I'm sorry I don't have more insight into what's wrong, I realize this is not a great bug report. Happy to provide any more details that might help track down the issue.

[ychin]

MacVim maintainer here. I'm trying to push the next version out anyway but trying to figure out a linker issue. May just try to punt until then (couple days max) to see if it fixes anything and how it behaves since it updates to using Python 3.8.

[clason]

@RobinClowers No, it turned out to be a user error 🤦 (Python 3.8 is stricter about specifying full locales, and I still had language en_US set in my vimrc, which was taken as the default LC_CTYPE locale when vimR was started from Finder -- as opposed to from a terminal, where the corresponding shell environment variable, which Apple Terminal magically sets correctly even without a .zshenv, are taken instead. Changing that to en_US.UTF-8 fixed my issue.)

Since the OP describes a reproducer with MacVim started from the terminal, I no longer think this is related.

[ipstone]

I would report the same/similar issue on linux brew - vim formula : the python3+ support is dropped from the brew vim. The previous version of vim has the correct python3+ compilation option enabled but not the current version. some vim plugins depend on python3 these days.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.