Re: [PATCH v2 20/29] grep: remove redundant `regflags &= ~REG_EXTENDED` assignments

[Junio C Hamano <gitster@pobox.com>]

Ævar Arnfjörð Bjarmason  <avarab@gmail.com> writes:

> Remove redundant assignments to the "regflags" variable. There are no
> code paths that have previously set the regflags to anything, and
> certainly not to `|= REG_EXTENDED`.
>
> This code gave the impression that it had to reset its environment,
> but it doesn't. This dates back to the initial introduction of
> git-grep in commit 5010cb5fcc ("built-in "git grep"", 2006-04-30).

Back in 5010cb5fcc, we did do "opt.regflags &= ~REG_EXTENDED" upon
seeing "-G" on the command line and flipped the bit on upon seeing
"-E", but I think that was perfectly sensible and it would have been
a bug if we didn't.  They were part of the command line parsing that
could have seen "-E" on the command line earlier.

If we want to find a commit to assign blame to, I think it is more
correct to say that this came from the same one as 19/29 fixes.

When cca2c172 ("git-grep: do not die upon -F/-P when
grep.extendedRegexp is set.", 2011-05-09) switched the command line
parsing to "read into a 'tentatively this is what we saw the last'
variable and then finally commit just once", we didn't touch
opt.regflags for PCRE and FIXED, but we still had to flip regflags
between BRE and ERE, because parsing of grep.extendedregexp
configuration variable directly touched opt.regflags back then,
which was done by b22520a3 ("grep: allow -E and -n to be turned on
by default via configuration", 2011-03-30).  When 84befcd0 ("grep:
add a grep.patternType configuration setting", 2012-08-03)
introduced extended_regexp_option field, we stopped flipping
regflags while reading the configuration, and that was when we
should have noticed and stopped dropping REG_EXTENDED bit in the
"now we can commit what type to use" helper function.

In any case, I think this change is safe to do in the current
codebase.  I wonder if this and 19/29 should be a single patch,
though, as the unnecessary bit-flipping all are blamed to the same
origin.

> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
> ---
>  grep.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/grep.c b/grep.c
> index 59ae7809f2..bf6c2494fd 100644
> --- a/grep.c
> +++ b/grep.c
> @@ -179,7 +179,6 @@ static void grep_set_pattern_type_option(enum grep_pattern_type pattern_type, st
>  	case GREP_PATTERN_TYPE_BRE:
>  		opt->fixed = 0;
>  		opt->pcre = 0;
> -		opt->regflags &= ~REG_EXTENDED;
>  		break;
>  
>  	case GREP_PATTERN_TYPE_ERE:
> @@ -191,7 +190,6 @@ static void grep_set_pattern_type_option(enum grep_pattern_type pattern_type, st
>  	case GREP_PATTERN_TYPE_FIXED:
>  		opt->fixed = 1;
>  		opt->pcre = 0;
> -		opt->regflags &= ~REG_EXTENDED;
>  		break;
>  
>  	case GREP_PATTERN_TYPE_PCRE:
> @@ -414,10 +412,9 @@ static void compile_fixed_regexp(struct grep_pat *p, struct grep_opt *opt)
>  {
>  	struct strbuf sb = STRBUF_INIT;
>  	int err;
> -	int regflags;
> +	int regflags = opt->regflags;
>  
>  	basic_regex_quote_buf(&sb, p->pattern);
> -	regflags = opt->regflags & ~REG_EXTENDED;
>  	if (opt->ignore_case)
>  		regflags |= REG_ICASE;
>  	err = regcomp(&p->regexp, sb.buf, regflags);