Re: [PATCH] regex: not all macOS platforms seem to have REG_ENHANCED
- From
Johannes Schindelin <johannes.schindelin@gmx.de>
- Date
- Mar 20, 2026, 08:06 UTC
- Message-ID
- <77b6ec9f-46a5-1f38-9733-188e20da55ec@gmx.de>
- In-Reply-To
- <6636e7d2-7a1d-0108-2e62-af27a3ae3cf3@gmx.de>
Me again,
On Fri, 20 Mar 2026, Johannes Schindelin wrote:
Show 41 quoted lines
> On Fri, 20 Mar 2026, Junio C Hamano wrote:
>
> > Earlier, 54463d32 (use enhanced basic regular expressions on macOS,
> > 2023-01-08) started to use the REG_ENHANCED option when ERE is not
> > in use on macOS. The build seems to have started failing on
> > macos-14 CI jobs at GitHub, however, as apparently not all the macOS
> > platforms have this flag defined.
> >
> > Signed-off-by: Junio C Hamano <gitster@pobox.com>
> > ---
> > compat/regcomp_enhanced.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/compat/regcomp_enhanced.c b/compat/regcomp_enhanced.c
> > index 84193ce53b..51e1358170 100644
> > --- a/compat/regcomp_enhanced.c
> > +++ b/compat/regcomp_enhanced.c
> > @@ -3,7 +3,9 @@
> >
> > int git_regcomp(regex_t *preg, const char *pattern, int cflags)
> > {
> > +#ifdef REG_ENHANCED
> > if (!(cflags & REG_EXTENDED))
> > cflags |= REG_ENHANCED;
> > +#endif
>
> While this lets the build pass, it _does_ change behavior. Where
> previously, EREs were enforced, now BREs are silently enforced.
>
> So it might be desirable to instead imitate what `meson.build` does,
> namely define `USE_ENHANCED_BASIC_REGULAR_EXPRESSIONS` on macOS when
> compiling with `clang`.
>
> But that should already be the case:
> https://gitlab.com/git-scm/git/-/blob/v2.53.0/config.mak.uname#L151
>
> > ifeq ($(uname_S),Darwin)
> > [...]
> > USE_ENHANCED_BASIC_REGULAR_EXPRESSIONS = YesPlease
>
> So: hmm.Ah. That flag _is_ the reason for the build error: I misunderstood what it is about. It is not telling the build process to compile with `compat/regex.c` and using enhanced regexes, it is telling the build process that whatever regex library is used _does_ support them.
So I need to pivot and recommend something like this in the `Darwin` clause in `config.mak.uname`:
-- snipsnap --
diff --git a/config.mak.uname b/config.mak.uname index f9ffefa67a4f..572f8967bc36 100644 --- a/config.mak.uname +++ b/config.mak.uname @@ -172,6 +172,10 @@ ifeq ($(uname_S),Darwin) NEEDS_GOOD_LIBICONV = UnfortunatelyYes endif + ifeq ($(CC),clang) + NO_REGEX = HomebrewsClangSeemsToBeMissingEnhancedRegexSupportAsOfMarch2026 + endif + # The builtin FSMonitor on MacOS builds upon Simple-IPC. Both require # Unix domain sockets and PThreads. ifndef NO_PTHREADS