grep/pcre: support utf-8

In the previous change in this function, we add locale support for
single-byte encodings only. It looks like pcre only supports utf-* as
multibyte encodings, the others are left in the cold (which is
fine).

We need to enable PCRE_UTF8 so pcre can find character boundary
correctly. It's needed for case folding (when --ignore-case is used)
or '*', '+' or similar syntax is used.

The "has_non_ascii()" check is to be on the conservative side. If
there's non-ascii in the pattern, the searched content could still be
in utf-8, but we can treat it just like a byte stream and everything
should work. If we force utf-8 based on locale only and pcre validates
utf-8 and the file content is in non-utf8 encoding, things break.

Noticed-by: Plamen Totev <plamen.totev@abv.bg>
Helped-by: Plamen Totev <plamen.totev@abv.bg>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/grep.c b/grep.c
index af920c4542..0e6511fe23 100644
--- a/grep.c
+++ b/grep.c
@@ -329,6 +329,8 @@ static void compile_pcre_regexp(struct grep_pat *p, const struct grep_opt *opt)
 			p->pcre_tables = pcre_maketables();
 		options |= PCRE_CASELESS;
 	}
+	if (is_utf8_locale() && has_non_ascii(p->pattern))
+		options |= PCRE_UTF8;
 
 	p->pcre_regexp = pcre_compile(p->pattern, options, &error, &erroffset,
 				      p->pcre_tables);