Re: BUG: git grep behave oddly with alternatives
From: Junio C Hamano <hidden>
Date: 2023-01-04 06:13:35
René Scharfe [off-list ref] 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.
quoted hunk
Reported-by: Marco Nenciarini <redacted> Signed-off-by: René Scharfe <redacted> --- 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_CRLFdiff --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 ofdiff --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