René Scharfe <l.s.r@xxxxxx> writes:
> "For enhanced basic REs, ‘+’, ‘?’ and ‘|’ remain regular characters,
> but ‘\+’, ‘\?’ and ‘\|’ have the same special meaning as the
> unescaped characters do for extended REs, i.e., one or more
> matches, zero or one matches and alteration, respectively."
>
> So apparently Apple chose a middle ground between basic and extended
> regular expressions for its grep and git grep.
Sounds like GNU extension to me.
> So GNU grep apparently made the same choice as Apple, probably far
> earlier.
Yup.
> Based on that I suggest:
> ...
>
> It would be simpler to use REG_ENHANCED everywhere it is defined instead
> of adding a Makefile setting, but it's a non-standard extension and
> might mean something else on other platforms.
OK. Very conservative and good.
> Reported-by: Marco Nenciarini <marco.nenciarini@xxxxxxxxxxxxxxxx>
> Signed-off-by: René Scharfe <l.s.r@xxxxxx>
> ---
> Makefile | 8 ++++++++
> config.mak.uname | 1 +
> grep.c | 4 ++++
> 3 files changed, 13 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index db447d0738..15e7edc9d2 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -289,6 +289,10 @@ include shared.mak
> # Define NO_REGEX if your C library lacks regex support with REG_STARTEND
> # feature.
> #
> +# Define GIT_GREP_USES_REG_ENHANCED if your C library provides the flag
> +# REG_ENHANCED to enable enhanced basic regular expressions and you'd
> +# like to use it in git grep.
> +#
> # Define HAVE_DEV_TTY if your system can open /dev/tty to interact with the
> # user.
> #
> @@ -2037,6 +2041,10 @@ endif
> ifdef NO_REGEX
> COMPAT_CFLAGS += -Icompat/regex
> COMPAT_OBJS += compat/regex/regex.o
> +else
> +ifdef GIT_GREP_USES_REG_ENHANCED
> + COMPAT_CFLAGS += -DGIT_GREP_USES_REG_ENHANCED
> +endif
> endif
> ifdef NATIVE_CRLF
> BASIC_CFLAGS += -DNATIVE_CRLF
> diff --git a/config.mak.uname b/config.mak.uname
> index d63629fe80..14c145ae42 100644
> --- a/config.mak.uname
> +++ b/config.mak.uname
> @@ -147,6 +147,7 @@ ifeq ($(uname_S),Darwin)
> FREAD_READS_DIRECTORIES = UnfortunatelyYes
> HAVE_NS_GET_EXECUTABLE_PATH = YesPlease
> CSPRNG_METHOD = arc4random
> + GIT_GREP_USES_REG_ENHANCED = YesPlease
>
> # Workaround for `gettext` being keg-only and not even being linked via
> # `brew link --force gettext`, should be obsolete as of
> diff --git a/grep.c b/grep.c
> index 06eed69493..a8430daaba 100644
> --- a/grep.c
> +++ b/grep.c
> @@ -502,6 +502,10 @@ static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
> regflags |= REG_ICASE;
> if (opt->pattern_type_option == GREP_PATTERN_TYPE_ERE)
> regflags |= REG_EXTENDED;
> +#if defined(GIT_GREP_USES_REG_ENHANCED) && defined(REG_ENHANCED)
> + else
> + regflags |= REG_ENHANCED;
> +#endif
> err = regcomp(&p->regexp, p->pattern, regflags);
> if (err) {
> char errbuf[1024];
> --
> 2.39.0
