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Cade's Dotfiles

Brew zsh tab completion leaves remnant characters (Linux)

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Source: Troubleshooting reference

Symptom: after pressing Tab, stale characters remain on the line instead of being erased.

Root cause chain:

  1. Brew zsh’s RUNPATH loads Homebrew’s own glibc (brew/opt/glibc/lib/libc.so.6)
  2. Homebrew’s glibc ships no lib/locale/ data → setlocale() silently falls back to C/ASCII
  3. In the C locale, wcwidth() returns byte counts instead of display columns
  4. Every cursor-position calculation in ZLE/completion is off → artifacts

Confirm by checking the codeset inside brew zsh:

Terminal window
zsh --no-rcs -c 'zmodload zsh/langinfo; echo $langinfo[CODESET]'
# broken:  ANSI_X3.4-1968
# working: UTF-8

Fix: linux-packages.sh generates en_US.UTF-8 and C.UTF-8 locale data for brew’s glibc into $LOCAL_PLAT/locale/ using brew’s own localedef. The shell profiles export LOCPATH pointing there so brew zsh picks it up at startup.

Both locales are needed: non-login processes can inherit LC_CTYPE=C.UTF-8 while the profile sets LANG=en_US.UTF-8. Without the category locale, brewed Perl reports Setting locale failed on each tlmgr invocation. Generating the matching data preserves the requested UTF-8 locale without suppressing warnings.

If you installed before this fix:

Terminal window
# Regenerate locale data
bash ~/dotfiles/install/linux-packages.sh


# Apply updated shell profiles (adds LOCPATH export)
chezmoi apply ~/.zprofile ~/.bash_profile


# Open a new login shell and verify
exec zsh -l
zsh --no-rcs -c 'zmodload zsh/langinfo; echo $langinfo[CODESET]'  # UTF-8

Test suite: bash ~/dotfiles/tests/test-locale.sh