Error: 'en_GB' cannot be parsed to a Locale

[rikbrown]

General troubleshooting steps

• I have retried my command with --force and the issue is still present.
• I have checked the instructions for reporting bugs.
• I made doubly sure this is not a checksum does not match error.
• I ran brew update-reset && brew update and retried my command.
• I ran brew doctor, fixed as many issues as possible and retried my command.
• I understand that if I ignore these instructions, my issue may be closed without review.

Description of issue

When I run brew cask install <app>, where <app> is a valid or invalid Cask name (but not an already installed Cask, which just prints the already installed method), I get a Error: 'en_GB' cannot be parsed to a Locale error message followed by a stack trace. Regular brew installs (non-cask) seem unaffected.

My region's preferred language is set to English (U.K.).

Naively, it seems like locale.rb is expecting a locale formatted like en-GB, but it is actually en_GB. I'm happy to submit a PR to fix this.

Command that failed

brew cask install lastpass

(though any valid or invalid, not yet installed, cask name triggers the failure).

Output of command with --force --verbose --debug

⋊> ~ brew cask install lastpass --force --verbose --debug                                                                                                                                                           11:38:30
Error: 'en_GB' cannot be parsed to a Locale
Follow the instructions here:
  https://github.com/Homebrew/homebrew-cask#reporting-bugs
/usr/local/Homebrew/Library/Homebrew/locale.rb:15:in `parse'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/dsl.rb:141:in `map'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/dsl.rb:141:in `language_eval'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/dsl.rb:115:in `language'
/usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask/Casks/torbrowser.rb:84:in `block in load'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cask.rb:40:in `instance_eval'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cask.rb:40:in `initialize'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cask_loader.rb:32:in `new'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cask_loader.rb:32:in `cask'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cask_loader.rb:76:in `cask'
/usr/local/Homebrew/Library/Homebrew/compat/hbc/cask_loader.rb:15:in `cask'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cask_loader.rb:122:in `cask'
/usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask/Casks/torbrowser.rb:1:in `load'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cask_loader.rb:59:in `instance_eval'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cask_loader.rb:59:in `load'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cask.rb:21:in `block in each'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cask.rb:19:in `each'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cask.rb:19:in `each'
/usr/local/Homebrew/Library/Homebrew/searchable.rb:27:in `select'
/usr/local/Homebrew/Library/Homebrew/searchable.rb:27:in `search_string'
/usr/local/Homebrew/Library/Homebrew/searchable.rb:7:in `search'
/usr/local/Homebrew/Library/Homebrew/extend/os/mac/search.rb:29:in `search_casks'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cli/abstract_command.rb:55:in `suggestion_message'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cli/abstract_command.rb:50:in `rescue in casks'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cli/abstract_command.rb:45:in `casks'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cli/install.rb:14:in `run'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cli/abstract_command.rb:33:in `run'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cli.rb:91:in `run_command'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cli.rb:157:in `run'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cli.rb:122:in `run'
/usr/local/Homebrew/Library/Homebrew/cmd/cask.rb:7:in `cask'
/usr/local/Homebrew/Library/Homebrew/brew.rb:87:in `<main>'
Error: Kernel.exit
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cli.rb:168:in `exit'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cli.rb:168:in `rescue in run'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cli.rb:145:in `run'
/usr/local/Homebrew/Library/Homebrew/cask/lib/hbc/cli.rb:122:in `run'
/usr/local/Homebrew/Library/Homebrew/cmd/cask.rb:7:in `cask'
/usr/local/Homebrew/Library/Homebrew/brew.rb:87:in `<main>'

Note: while the failure is coming from torbrowser.rb, this just appears to be during loading everything. Manually removing this Cask just triggers the error on another Cask.

Output of brew cask doctor

==> Homebrew-Cask Version
Homebrew-Cask 1.7.1-220-g46f531b
Homebrew/homebrew-cask (git revision 1c325; last commit 2018-08-12)
==> macOS
10.13.6
==> SIP
Enabled
==> Java
10.0.1
==> Homebrew-Cask Install Location
<NONE>
==> Homebrew-Cask Staging Location
/usr/local/Caskroom
==> Homebrew-Cask Cached Downloads
~/Library/Caches/Homebrew/Cask (7 files, 664.7MB)
==> Homebrew-Cask Taps:
/usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask (4023 casks)
/usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask-fonts (1164 casks)
/usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask-drivers (152 casks)
==> Contents of $LOAD_PATH
/usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.3.7/lib/ruby/gems/2.3.0/gems/did_you_mean-1.0.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.3.7/lib/ruby/site_ruby/2.3.0
/usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.3.7/lib/ruby/site_ruby/2.3.0/x86_64-darwin9.0
/usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.3.7/lib/ruby/site_ruby/2.3.0/universal-darwin9.0
/usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.3.7/lib/ruby/site_ruby
/usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.3.7/lib/ruby/vendor_ruby/2.3.0
/usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.3.7/lib/ruby/vendor_ruby/2.3.0/x86_64-darwin9.0
/usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.3.7/lib/ruby/vendor_ruby/2.3.0/universal-darwin9.0
/usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.3.7/lib/ruby/vendor_ruby
/usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.3.7/lib/ruby/2.3.0
/usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.3.7/lib/ruby/2.3.0/x86_64-darwin9.0
/usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.3.7/lib/ruby/2.3.0/universal-darwin9.0
/usr/local/Homebrew/Library/Homebrew/cask/lib
/usr/local/Homebrew/Library/Homebrew
==> Environment Variables
LC_ALL="en_US.UTF-8"
PATH="/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/Homebrew/Library/Homebrew/shims/scm"
SHELL="/usr/local/bin/fish"

Output of brew tap

⋊> ~ brew tap                                                                                                                                                                                                       11:39:14
homebrew/bundle
homebrew/cask
homebrew/cask-drivers
homebrew/cask-fonts
homebrew/core

[rikbrown]

Ok, after writing that up I discovered the issue. I had manually configured by Preferred languages using the following command: defaults write -g AppleLanguages -array "en_GB" "en_US". Other applications and macOS accepted this (appearing correctly in Language & Region), but after resetting this by reordering the list using the Language & Region preference pane, I see that macOS writes it using en-GB (dashes not underscores).

Confusingly, other defaults values (like AppleLocale) use underscores.

It looks like formally - is correct (but Java used _). Nice and consistent. We can close this as standard system locale setup will work with the existing code.