grep/icase: avoid kwsset on literal non-ascii strings

When we detect the pattern is just a literal string, we avoid heavy
regex engine and use fast substring search implemented in kwsset.c.
But kws uses git-ctype which is locale-independent so it does not know
how to fold case properly outside ascii range. Let regcomp or pcre
take care of this case instead. Slower, but accurate.

Noticed-by: Plamen Totev <plamen.totev@abv.bg>
Helped-by: René Scharfe <l.s.r@web.de>
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/t/t7812-grep-icase-non-ascii.sh b/t/t7812-grep-icase-non-ascii.sh
new file mode 100755
index 0000000000..b78a774dab
--- /dev/null
+++ b/t/t7812-grep-icase-non-ascii.sh
@@ -0,0 +1,23 @@
+#!/bin/sh
+
+test_description='grep icase on non-English locales'
+
+. ./lib-gettext.sh
+
+test_expect_success GETTEXT_LOCALE 'setup' '
+	test_write_lines "TILRAUN: Halló Heimur!" >file &&
+	git add file &&
+	LC_ALL="$is_IS_locale" &&
+	export LC_ALL
+'
+
+test_have_prereq GETTEXT_LOCALE &&
+test-regex "HALLÓ" "Halló" ICASE &&
+test_set_prereq REGEX_LOCALE
+
+test_expect_success REGEX_LOCALE 'grep literal string, no -F' '
+	git grep -i "TILRAUN: Halló Heimur!" &&
+	git grep -i "TILRAUN: HALLÓ HEIMUR!"
+'
+
+test_done