Is 'LANG' env-var being filtered out of 'brew' for any valid reason that I'm unaware of?

[jamesrtnz]

Additional Info

• I am using Windows Subsystem for Linux

Output of brew config

HOMEBREW_VERSION: 5.1.4
ORIGIN: https://github.com/Homebrew/brew
HEAD: 968378a218ba485371a8a849185f05a8b534bda7
Last commit: 2 days ago
Branch: stable
Core tap HEAD: da8b773c3dc988209b5053d36125d26e2c2815d9
Core tap last commit: 27 hours ago
Core tap JSON: 07 Oct 02:16 UTC
HOMEBREW_PREFIX: /home/linuxbrew/.linuxbrew
HOMEBREW_BAT: set
HOMEBREW_CASK_OPTS: ["--no-quarantine"]
HOMEBREW_DOWNLOAD_CONCURRENCY: 4
HOMEBREW_FORBID_PACKAGES_FROM_PATHS: set
HOMEBREW_MAKE_JOBS: 2
HOMEBREW_NO_ENV_HINTS: set
HOMEBREW_NO_INSTALL_FROM_API: set
HOMEBREW_TEMP: /home/USERNAME/tmp
http_proxy: http://localhost:3128/
https_proxy: http://localhost:3128/
no_proxy: localhost,127.0.0.0/24
Homebrew Ruby: 4.0.2 => /home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/vendor/portable-ruby/4.0.2_1/bin/ruby
CPU: dual-core 64-bit zen2
Clang: N/A
Git: 2.47.3 => /bin/git
Curl: 7.76.1 => /bin/curl
Kernel: Linux 5.14.0-611.42.1.el9_7.x86_64 x86_64 GNU/Linux
OS: Red Hat Enterprise Linux 9.7 (Plow)
Host glibc: 2.34
Host libstdc++: 6.0.29
/usr/bin/gcc: 11.5.0
/usr/bin/ruby: N/A
glibc: 2.39
gcc@12: N/A
gcc: 15.2.0_1
xorg: N/A

Output of brew doctor

Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry or file an issue; just ignore this. Thanks!

Warning: Your system glibc 2.34 is too old.
We will need to automatically install a newer version.

We recommend updating to a newer version via your distribution's
package manager, upgrading your distribution to the latest version,
or changing distributions.

This is a Tier 2 configuration:
  https://docs.brew.sh/Support-Tiers#tier-2
You can report issues with Tier 2 configurations to Homebrew/* repositories!
Read the above document before opening any issues or PRs.

Description of issue

A couple of days ago, there was a glibc update in Homebrew, with the result that my locale data got lost (again!), and I was getting locale warnings from various homebrew components, like perl, for example:

$ perl --version
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
...

Whilst this is easily fixed via /home/linuxbrew/.linuxbrew/Cellar/glibc/2.39/bin/localedef -i en_NZ -f UTF-8 en_NZ.UTF-8, I notice that the glibc.rb formula itself actually supports doing this automatically in the post_install, via this code:

    # Get all extra installed locales from the system, except C locales
    locales = ENV.filter_map do |k, v|
      v if k[/^LANG$|^LC_/] && v != "C" && !v.start_with?("C.")
    end

    # en_US.UTF-8 is required by gawk make check
    locales = (locales + ["en_US.UTF-8"]).sort.uniq
    ohai "Installing locale data for #{locales.join(" ")}"
    locales.each do |locale|
      lang, charmap = locale.split(".", 2)
      if charmap.present?
        charmap = "UTF-8" if charmap == "utf8"
        system bin/"localedef", "-i", lang, "-f", charmap, locale
      else
        system bin/"localedef", "-i", lang, locale
      end
    end

However, this doesn't actually work, as the 'brew' wrapper filters the current environment before this postinstall gets to run, and LANG (and LC_*) are stripped out of the environment as part of this.

There are open issues dating back to 2022 which note this behaviour - so is there a really good reason why this hasn't been fixed yet?

All that's required would be to add "LANG" to the list of variables that are included in the filter....

[SMillerDev]

There are open issues dating back to 2022 which note this behaviour - so is there a really good reason why this hasn't been fixed yet?

Clearly nobody felt like fixing it and the license for brew says that it is provided "AS IS", so nobody needs a really good reason.
You're always welcome to submit a pull request to fix issues you've found though.

[jamesrtnz]

That's fine; I'm happy to do a PR for this; I was just trying to check that there wasn't some overriding rationale I had missed prior to doing so. I'm a bit of a newbie when it comes to actually contributing to open source software...

[jamesrtnz]

Have raised Homebrew/brew#21945

[jamesrtnz]

And the matching PR for 'glibc.rb' as suggest by MikeMcQuaid is Homebrew/homebrew-core#276609