I'm encountering a failure on macOS High Sierra 10.13.6 when using --color-words: % git show --color-words HEAD fatal: invalid regular expression: [[:alpha:]_'][[:alnum:]_']*|0[xb]?[0-9a-fA-F_]*|[0-9a-fA-F_]+(\.[0-9a-fA-F_]+)?([eE][-+]?[0-9_]+)?|=>|-[rwxoRWXOezsfdlpSugkbctTBMAC>]|~~|::|&&=|\|\|=|//=|\*\*=|&&|\|\||//|\+\+|--|\*\*|\.\.\.?|[-+*/%.^&<>=!|]=|=~|!~|<<|<>|<=>|>>|[^[:space:]]|[<C0>-<FF>][<80>-<BF>]+ This crash happens when viewing the commit I sent to Peff today[1], though it doesn't happen with all commits. The problem bisects to: Author: Diomidis Spinellis <dds@xxxxxxx> Date: Fri Aug 26 11:58:15 2022 +0300 grep: fix multibyte regex handling under macOS The commit 29de20504e (Makefile: fix default regex settings on Darwin, 2013-05-11) fixed t0070-fundamental.sh under Darwin (macOS) by adopting Git's regex library. However, this library is compiled with NO_MBSUPPORT, which causes git-grep to work incorrectly on multibyte (e.g. UTF-8) files. Current macOS versions pass t0070-fundamental.sh with the native macOS regex library, which also supports multibyte characters. Adjust the Makefile to use the native regex library, and call setlocale(3) to set CTYPE according to the user's preference. The setlocale call is required on all platforms, but in platforms supporting gettext(3), setlocale was called as a side-effect of initializing gettext. Therefore, move the CTYPE setlocale call from gettext.c to common-main.c and the corresponding locale.h include into git-compat-util.h. Thanks to the global initialization of CTYPE setlocale, the test-tool regex command now works correctly with supported multibyte regexes, and is used to set the MB_REGEX test prerequisite by assessing a platform's support for them. Signed-off-by: Diomidis Spinellis <dds@xxxxxxx> Signed-off-by: Junio C Hamano <gitster@xxxxxxxxx> I see that this same commit is also the subject of another bug report currently being discussed[2], so I've Cc:'d the participants of that thread, as well. Any pointers aimed at getting this resolved would be appreciated. [1]: https://lore.kernel.org/git/CAPig+cQiOGrDSUc34jHEBp87Rx-dnXNcPcF76bu0SJoOzD+1hw@xxxxxxxxxxxxxx/ [2]: https://lore.kernel.org/git/MW4PR20MB5517583CBEEF34B1E87CCF1290859@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/