patch, 29 partsEasy to review grep & pre-PCRE changes

Documentation/git-grep.txt, Documentation/rev-list-options.txt

diff --git a/Documentation/git-grep.txt b/Documentation/git-grep.txt
index 71f32f3508..5033483db4 100644
--- a/Documentation/git-grep.txt
+++ b/Documentation/git-grep.txt
@@ -161,8 +161,11 @@ OPTIONS
 
 -P::
 --perl-regexp::
-	Use Perl-compatible regexp for patterns. Requires libpcre to be
-	compiled in.
+	Use Perl-compatible regular expressions for patterns.
++
+Support for these types of regular expressions is an optional
+compile-time dependency. If Git wasn't compiled with support for them
+providing this option will cause it to die.
 
 -F::
 --fixed-strings::
diff --git a/Documentation/rev-list-options.txt b/Documentation/rev-list-options.txt
index a02f7324c0..a46f70c2b1 100644
--- a/Documentation/rev-list-options.txt
+++ b/Documentation/rev-list-options.txt
@@ -92,8 +92,12 @@ endif::git-rev-list[]
 	pattern as a regular expression).
 
 --perl-regexp::
-	Consider the limiting patterns to be Perl-compatible regular expressions.
-	Requires libpcre to be compiled in.
+	Consider the limiting patterns to be Perl-compatible regular
+	expressions.
++
+Support for these types of regular expressions is an optional
+compile-time dependency. If Git wasn't compiled with support for them
+providing this option will cause it to die.
 
 --remove-empty::
 	Stop when a given path disappears from the tree.

t/README, t/t7810-grep.sh, t/t7812-grep-icase-non-ascii.sh, t/t7813-grep-icase-iso.sh, t/test-lib.sh

diff --git a/t/README b/t/README
index ab386c3681..a90cb62583 100644
--- a/t/README
+++ b/t/README
@@ -803,9 +803,9 @@ use these, and "test_set_prereq" for how to define your own.
    Test is not run by root user, and an attempt to write to an
    unwritable file is expected to fail correctly.
 
- - LIBPCRE
+ - PCRE
 
-   Git was compiled with USE_LIBPCRE=YesPlease. Wrap any tests
+   Git was compiled with support for PCRE. Wrap any tests
    that use git-grep --perl-regexp or git-grep -P in these.
 
  - CASE_INSENSITIVE_FS
diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index cee42097b0..c84c4d99f9 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -275,7 +275,7 @@ do
 		test_cmp expected actual
 	'
 
-	test_expect_success LIBPCRE "grep $L with grep.patterntype=perl" '
+	test_expect_success PCRE "grep $L with grep.patterntype=perl" '
 		echo "${HC}ab:a+b*c" >expected &&
 		git -c grep.patterntype=perl grep "a\x{2b}b\x{2a}c" $H ab >actual &&
 		test_cmp expected actual
@@ -1053,12 +1053,12 @@ hello.c:int main(int argc, const char **argv)
 hello.c:	printf("Hello world.\n");
 EOF
 
-test_expect_success LIBPCRE 'grep --perl-regexp pattern' '
+test_expect_success PCRE 'grep --perl-regexp pattern' '
 	git grep --perl-regexp "\p{Ps}.*?\p{Pe}" hello.c >actual &&
 	test_cmp expected actual
 '
 
-test_expect_success LIBPCRE 'grep -P pattern' '
+test_expect_success PCRE 'grep -P pattern' '
 	git grep -P "\p{Ps}.*?\p{Pe}" hello.c >actual &&
 	test_cmp expected actual
 '
@@ -1070,13 +1070,13 @@ test_expect_success 'grep pattern with grep.extendedRegexp=true' '
 	test_cmp empty actual
 '
 
-test_expect_success LIBPCRE 'grep -P pattern with grep.extendedRegexp=true' '
+test_expect_success PCRE 'grep -P pattern with grep.extendedRegexp=true' '
 	git -c grep.extendedregexp=true \
 		grep -P "\p{Ps}.*?\p{Pe}" hello.c >actual &&
 	test_cmp expected actual
 '
 
-test_expect_success LIBPCRE 'grep -P -v pattern' '
+test_expect_success PCRE 'grep -P -v pattern' '
 	{
 		echo "ab:a+b*c"
 		echo "ab:a+bc"
@@ -1085,7 +1085,7 @@ test_expect_success LIBPCRE 'grep -P -v pattern' '
 	test_cmp expected actual
 '
 
-test_expect_success LIBPCRE 'grep -P -i pattern' '
+test_expect_success PCRE 'grep -P -i pattern' '
 	cat >expected <<-EOF &&
 	hello.c:	printf("Hello world.\n");
 	EOF
@@ -1093,7 +1093,7 @@ test_expect_success LIBPCRE 'grep -P -i pattern' '
 	test_cmp expected actual
 '
 
-test_expect_success LIBPCRE 'grep -P -w pattern' '
+test_expect_success PCRE 'grep -P -w pattern' '
 	{
 		echo "hello_world:Hello world"
 		echo "hello_world:HeLLo world"
@@ -1118,11 +1118,11 @@ test_expect_success 'grep invalidpattern properly dies with grep.patternType=ext
 	test_must_fail git -c grep.patterntype=extended grep "a["
 '
 
-test_expect_success LIBPCRE 'grep -P invalidpattern properly dies ' '
+test_expect_success PCRE 'grep -P invalidpattern properly dies ' '
 	test_must_fail git grep -P "a["
 '
 
-test_expect_success LIBPCRE 'grep invalidpattern properly dies with grep.patternType=perl' '
+test_expect_success PCRE 'grep invalidpattern properly dies with grep.patternType=perl' '
 	test_must_fail git -c grep.patterntype=perl grep "a["
 '
 
@@ -1191,13 +1191,13 @@ test_expect_success 'grep pattern with grep.patternType=fixed, =basic, =perl, =e
 	test_cmp expected actual
 '
 
-test_expect_success LIBPCRE 'grep -G -F -E -P pattern' '
+test_expect_success PCRE 'grep -G -F -E -P pattern' '
 	echo "d0:0" >expected &&
 	git grep -G -F -E -P "[\d]" d0 >actual &&
 	test_cmp expected actual
 '
 
-test_expect_success LIBPCRE 'grep pattern with grep.patternType=fixed, =basic, =extended, =perl' '
+test_expect_success PCRE 'grep pattern with grep.patternType=fixed, =basic, =extended, =perl' '
 	echo "d0:0" >expected &&
 	git \
 		-c grep.patterntype=fixed \
@@ -1208,7 +1208,7 @@ test_expect_success LIBPCRE 'grep pattern with grep.patternType=fixed, =basic, =
 	test_cmp expected actual
 '
 
-test_expect_success LIBPCRE 'grep -P pattern with grep.patternType=fixed' '
+test_expect_success PCRE 'grep -P pattern with grep.patternType=fixed' '
 	echo "ab:a+b*c" >expected &&
 	git \
 		-c grep.patterntype=fixed \
@@ -1343,12 +1343,12 @@ space: line with leading space2
 space: line with leading space3
 EOF
 
-test_expect_success LIBPCRE 'grep -E "^ "' '
+test_expect_success PCRE 'grep -E "^ "' '
 	git grep -E "^ " space >actual &&
 	test_cmp expected actual
 '
 
-test_expect_success LIBPCRE 'grep -P "^ "' '
+test_expect_success PCRE 'grep -P "^ "' '
 	git grep -P "^ " space >actual &&
 	test_cmp expected actual
 '
diff --git a/t/t7812-grep-icase-non-ascii.sh b/t/t7812-grep-icase-non-ascii.sh
index 169fd8d706..04a61cb8e0 100755
--- a/t/t7812-grep-icase-non-ascii.sh
+++ b/t/t7812-grep-icase-non-ascii.sh
@@ -20,13 +20,13 @@ test_expect_success REGEX_LOCALE 'grep literal string, no -F' '
 	git grep -i "TILRAUN: HALLÓ HEIMUR!"
 '
 
-test_expect_success GETTEXT_LOCALE,LIBPCRE 'grep pcre utf-8 icase' '
+test_expect_success GETTEXT_LOCALE,PCRE 'grep pcre utf-8 icase' '
 	git grep --perl-regexp    "TILRAUN: H.lló Heimur!" &&
 	git grep --perl-regexp -i "TILRAUN: H.lló Heimur!" &&
 	git grep --perl-regexp -i "TILRAUN: H.LLÓ HEIMUR!"
 '
 
-test_expect_success GETTEXT_LOCALE,LIBPCRE 'grep pcre utf-8 string with "+"' '
+test_expect_success GETTEXT_LOCALE,PCRE 'grep pcre utf-8 string with "+"' '
 	test_write_lines "TILRAUN: Hallóó Heimur!" >file2 &&
 	git add file2 &&
 	git grep -l --perl-regexp "TILRAUN: H.lló+ Heimur!" >actual &&
diff --git a/t/t7813-grep-icase-iso.sh b/t/t7813-grep-icase-iso.sh
index efef7fb81f..701e08a8e5 100755
--- a/t/t7813-grep-icase-iso.sh
+++ b/t/t7813-grep-icase-iso.sh
@@ -11,7 +11,7 @@ test_expect_success GETTEXT_ISO_LOCALE 'setup' '
 	export LC_ALL
 '
 
-test_expect_success GETTEXT_ISO_LOCALE,LIBPCRE 'grep pcre string' '
+test_expect_success GETTEXT_ISO_LOCALE,PCRE 'grep pcre string' '
 	git grep --perl-regexp -i "TILRAUN: H.ll� Heimur!" &&
 	git grep --perl-regexp -i "TILRAUN: H.LL� HEIMUR!"
 '
diff --git a/t/test-lib.sh b/t/test-lib.sh
index 13b5696822..6abf1d1918 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -1010,7 +1010,7 @@ esac
 ( COLUMNS=1 && test $COLUMNS = 1 ) && test_set_prereq COLUMNS_CAN_BE_1
 test -z "$NO_PERL" && test_set_prereq PERL
 test -z "$NO_PYTHON" && test_set_prereq PYTHON
-test -n "$USE_LIBPCRE" && test_set_prereq LIBPCRE
+test -n "$USE_LIBPCRE" && test_set_prereq PCRE
 test -z "$NO_GETTEXT" && test_set_prereq GETTEXT
 
 # Can we rely on git's output in the C locale?

Makefile, configure.ac

diff --git a/Makefile b/Makefile
index e35542e631..eedadb8056 100644
--- a/Makefile
+++ b/Makefile
@@ -24,8 +24,10 @@ all::
 # Define NO_OPENSSL environment variable if you do not have OpenSSL.
 # This also implies BLK_SHA1.
 #
-# Define USE_LIBPCRE if you have and want to use libpcre. git-grep will be
-# able to use Perl-compatible regular expressions.
+# Define USE_LIBPCRE if you have and want to use libpcre. Various
+# commands such as log and grep offer runtime options to use
+# Perl-compatible regular expressions instead of standard or extended
+# POSIX regular expressions.
 #
 # Define LIBPCREDIR=/foo/bar if your libpcre header and library files are in
 # /foo/bar/include and /foo/bar/lib directories.
diff --git a/configure.ac b/configure.ac
index 128165529f..deeb968daa 100644
--- a/configure.ac
+++ b/configure.ac
@@ -250,8 +250,10 @@ AS_HELP_STRING([--with-openssl],[use OpenSSL library (default is YES)])
 AS_HELP_STRING([],              [ARG can be prefix for openssl library and headers]),
 GIT_PARSE_WITH([openssl]))
 
-# Define USE_LIBPCRE if you have and want to use libpcre. git-grep will be
-# able to use Perl-compatible regular expressions.
+# Define USE_LIBPCRE if you have and want to use libpcre. Various
+# commands such as log and grep offer runtime options to use
+# Perl-compatible regular expressions instead of standard or extended
+# POSIX regular expressions.
 #
 # Define LIBPCREDIR=/foo/bar if your libpcre header and library files are in
 # /foo/bar/include and /foo/bar/lib directories.
@@ -499,8 +501,10 @@ GIT_CONF_SUBST([NEEDS_SSL_WITH_CRYPTO])
 GIT_CONF_SUBST([NO_OPENSSL])
 
 #
-# Define USE_LIBPCRE if you have and want to use libpcre. git-grep will be
-# able to use Perl-compatible regular expressions.
+# Define USE_LIBPCRE if you have and want to use libpcre. Various
+# commands such as log and grep offer runtime options to use
+# Perl-compatible regular expressions instead of standard or extended
+# POSIX regular expressions.
 #
 
 if test -n "$USE_LIBPCRE"; then

diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index f577990716..6d1411abea 100755
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -262,7 +262,23 @@ test_expect_success 'log --grep -i' '
 
 test_expect_success 'log -F -E --grep=<ere> uses ere' '
 	echo second >expect &&
-	git log -1 --pretty="tformat:%s" -F -E --grep=s.c.nd >actual &&
+	git log -1 --pretty="tformat:%s" -F -E --grep="(s).c.nd" >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success PCRE 'log -F -E --perl-regexp --grep=<pcre> uses PCRE' '
+	test_when_finished "rm -rf num_commits" &&
+	git init num_commits &&
+	(
+		cd num_commits &&
+		test_commit 1d &&
+		test_commit 2e
+	) &&
+	echo 2e >expect &&
+	git -C num_commits log -1 --pretty="tformat:%s" -F -E --perl-regexp --grep="[\d]" >actual &&
+	test_cmp expect actual &&
+	echo 1d >expect &&
+	git -C num_commits log -1 --pretty="tformat:%s" -F -E --grep="[\d]" >actual &&
 	test_cmp expect actual
 '
 
@@ -280,6 +296,65 @@ test_expect_success 'log with grep.patternType configuration and command line' '
 	test_cmp expect actual
 '
 
+test_expect_success 'log with various grep.patternType configurations & command-lines' '
+	git init pattern-type &&
+	(
+		cd pattern-type &&
+		test_commit 1 file A &&
+		test_commit "(1|2)" file B &&
+
+		echo "(1|2)" >expect.fixed &&
+		cp expect.fixed expect.basic &&
+		cp expect.fixed expect.extended &&
+		cp expect.fixed expect.perl &&
+
+		git -c grep.patternType=fixed log --pretty=tformat:%s \
+			--grep="(1|2)" >actual.fixed &&
+		git -c grep.patternType=basic log --pretty=tformat:%s \
+			--grep="(.|.)" >actual.basic &&
+		git -c grep.patternType=extended log --pretty=tformat:%s \
+			--grep="\|2" >actual.extended &&
+		if test_have_prereq PCRE
+		then
+			git -c grep.patternType=perl log --pretty=tformat:%s \
+				--grep="[\d]\|" >actual.perl
+		fi &&
+		test_cmp expect.fixed actual.fixed &&
+		test_cmp expect.basic actual.basic &&
+		test_cmp expect.extended actual.extended &&
+		if test_have_prereq PCRE
+		then
+			test_cmp expect.perl actual.perl
+		fi &&
+
+		git log --pretty=tformat:%s -F \
+			--grep="(1|2)" >actual.fixed.short-arg &&
+		git log --pretty=tformat:%s -E \
+			--grep="\|2" >actual.extended.short-arg &&
+		test_cmp expect.fixed actual.fixed.short-arg &&
+		test_cmp expect.extended actual.extended.short-arg &&
+
+		git log --pretty=tformat:%s --fixed-strings \
+			--grep="(1|2)" >actual.fixed.long-arg &&
+		git log --pretty=tformat:%s --basic-regexp \
+			--grep="(.|.)" >actual.basic.long-arg &&
+		git log --pretty=tformat:%s --extended-regexp \
+			--grep="\|2" >actual.extended.long-arg &&
+		if test_have_prereq PCRE
+		then
+			git log --pretty=tformat:%s --perl-regexp \
+				--grep="[\d]\|" >actual.perl.long-arg
+		fi &&
+		test_cmp expect.fixed actual.fixed.long-arg &&
+		test_cmp expect.basic actual.basic.long-arg &&
+		test_cmp expect.extended actual.extended.long-arg &&
+		if test_have_prereq PCRE
+		then
+			test_cmp expect.perl actual.perl.long-arg
+		fi
+	)
+'
+
 cat > expect <<EOF
 * Second
 * sixth

diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index 8d69113695..daa906b9b0 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -1114,6 +1114,13 @@ test_expect_success PCRE 'grep -P -w pattern' '
 	test_cmp expected actual
 '
 
+test_expect_success PCRE 'grep -P backreferences work (the PCRE NO_AUTO_CAPTURE flag is not set)' '
+	git grep -P -h "(?P<one>.)(?P=one)" hello_world >actual &&
+	test_cmp hello_world actual &&
+	git grep -P -h "(.)\1" hello_world >actual &&
+	test_cmp hello_world actual
+'
+
 test_expect_success 'grep -G invalidpattern properly dies ' '
 	test_must_fail git grep -G "a["
 '

t/t4202-log.sh, t/t7810-grep.sh

diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index 6d1411abea..b0122a1991 100755
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -344,6 +344,9 @@ test_expect_success 'log with various grep.patternType configurations & command-
 		then
 			git log --pretty=tformat:%s --perl-regexp \
 				--grep="[\d]\|" >actual.perl.long-arg
+		else
+			test_must_fail git log --perl-regexp \
+				--grep="[\d]\|"
 		fi &&
 		test_cmp expect.fixed actual.fixed.long-arg &&
 		test_cmp expect.basic actual.basic.long-arg &&
diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index c84c4d99f9..8d69113695 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -281,6 +281,10 @@ do
 		test_cmp expected actual
 	'
 
+	test_expect_success !PCRE "grep $L with grep.patterntype=perl errors without PCRE" '
+		test_must_fail git -c grep.patterntype=perl grep "foo.*bar"
+	'
+
 	test_expect_success "grep $L with grep.patternType=default and grep.extendedRegexp=true" '
 		echo "${HC}ab:abc" >expected &&
 		git \
@@ -1058,11 +1062,19 @@ test_expect_success PCRE 'grep --perl-regexp pattern' '
 	test_cmp expected actual
 '
 
+test_expect_success !PCRE 'grep --perl-regexp pattern errors without PCRE' '
+	test_must_fail git grep --perl-regexp "foo.*bar"
+'
+
 test_expect_success PCRE 'grep -P pattern' '
 	git grep -P "\p{Ps}.*?\p{Pe}" hello.c >actual &&
 	test_cmp expected actual
 '
 
+test_expect_success !PCRE 'grep -P pattern errors without PCRE' '
+	test_must_fail git grep -P "foo.*bar"
+'
+
 test_expect_success 'grep pattern with grep.extendedRegexp=true' '
 	>empty &&
 	test_must_fail git -c grep.extendedregexp=true \

diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index daa906b9b0..561709ef6a 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -775,6 +775,22 @@ test_expect_success 'grep -W with userdiff' '
 	test_cmp expected actual
 '
 
+for threads in $(test_seq 0 10)
+do
+	test_expect_success "grep --threads=$threads & -c grep.threads=$threads" "
+		git grep --threads=$threads . >actual.$threads &&
+		if test $threads -ge 1
+		then
+			test_cmp actual.\$(($threads - 1)) actual.$threads
+		fi &&
+		git -c grep.threads=$threads grep . >actual.$threads &&
+		if test $threads -ge 1
+		then
+			test_cmp actual.\$(($threads - 1)) actual.$threads
+		fi
+	"
+done
+
 test_expect_success 'grep from a subdirectory to search wider area (1)' '
 	mkdir -p s &&
 	(

diff --git a/t/t7814-grep-recurse-submodules.sh b/t/t7814-grep-recurse-submodules.sh
index 5b6eb3a65e..3c580b38ba 100755
--- a/t/t7814-grep-recurse-submodules.sh
+++ b/t/t7814-grep-recurse-submodules.sh
@@ -9,13 +9,13 @@ submodules.
 . ./test-lib.sh
 
 test_expect_success 'setup directory structure and submodule' '
-	echo "foobar" >a &&
+	echo "(1|2)d(3|4)" >a &&
 	mkdir b &&
-	echo "bar" >b/b &&
+	echo "(3|4)" >b/b &&
 	git add a b &&
 	git commit -m "add a and b" &&
 	git init submodule &&
-	echo "foobar" >submodule/a &&
+	echo "(1|2)d(3|4)" >submodule/a &&
 	git -C submodule add a &&
 	git -C submodule commit -m "add a" &&
 	git submodule add ./submodule &&
@@ -24,18 +24,18 @@ test_expect_success 'setup directory structure and submodule' '
 
 test_expect_success 'grep correctly finds patterns in a submodule' '
 	cat >expect <<-\EOF &&
-	a:foobar
-	b/b:bar
-	submodule/a:foobar
+	a:(1|2)d(3|4)
+	b/b:(3|4)
+	submodule/a:(1|2)d(3|4)
 	EOF
 
-	git grep -e "bar" --recurse-submodules >actual &&
+	git grep -e "(3|4)" --recurse-submodules >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep and basic pathspecs' '
 	cat >expect <<-\EOF &&
-	submodule/a:foobar
+	submodule/a:(1|2)d(3|4)
 	EOF
 
 	git grep -e. --recurse-submodules -- submodule >actual &&
@@ -44,7 +44,7 @@ test_expect_success 'grep and basic pathspecs' '
 
 test_expect_success 'grep and nested submodules' '
 	git init submodule/sub &&
-	echo "foobar" >submodule/sub/a &&
+	echo "(1|2)d(3|4)" >submodule/sub/a &&
 	git -C submodule/sub add a &&
 	git -C submodule/sub commit -m "add a" &&
 	git -C submodule submodule add ./sub &&
@@ -54,117 +54,117 @@ test_expect_success 'grep and nested submodules' '
 	git commit -m "updated submodule" &&
 
 	cat >expect <<-\EOF &&
-	a:foobar
-	b/b:bar
-	submodule/a:foobar
-	submodule/sub/a:foobar
+	a:(1|2)d(3|4)
+	b/b:(3|4)
+	submodule/a:(1|2)d(3|4)
+	submodule/sub/a:(1|2)d(3|4)
 	EOF
 
-	git grep -e "bar" --recurse-submodules >actual &&
+	git grep -e "(3|4)" --recurse-submodules >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep and multiple patterns' '
 	cat >expect <<-\EOF &&
-	a:foobar
-	submodule/a:foobar
-	submodule/sub/a:foobar
+	a:(1|2)d(3|4)
+	submodule/a:(1|2)d(3|4)
+	submodule/sub/a:(1|2)d(3|4)
 	EOF
 
-	git grep -e "bar" --and -e "foo" --recurse-submodules >actual &&
+	git grep -e "(3|4)" --and -e "(1|2)d" --recurse-submodules >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep and multiple patterns' '
 	cat >expect <<-\EOF &&
-	b/b:bar
+	b/b:(3|4)
 	EOF
 
-	git grep -e "bar" --and --not -e "foo" --recurse-submodules >actual &&
+	git grep -e "(3|4)" --and --not -e "(1|2)d" --recurse-submodules >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'basic grep tree' '
 	cat >expect <<-\EOF &&
-	HEAD:a:foobar
-	HEAD:b/b:bar
-	HEAD:submodule/a:foobar
-	HEAD:submodule/sub/a:foobar
+	HEAD:a:(1|2)d(3|4)
+	HEAD:b/b:(3|4)
+	HEAD:submodule/a:(1|2)d(3|4)
+	HEAD:submodule/sub/a:(1|2)d(3|4)
 	EOF
 
-	git grep -e "bar" --recurse-submodules HEAD >actual &&
+	git grep -e "(3|4)" --recurse-submodules HEAD >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep tree HEAD^' '
 	cat >expect <<-\EOF &&
-	HEAD^:a:foobar
-	HEAD^:b/b:bar
-	HEAD^:submodule/a:foobar
+	HEAD^:a:(1|2)d(3|4)
+	HEAD^:b/b:(3|4)
+	HEAD^:submodule/a:(1|2)d(3|4)
 	EOF
 
-	git grep -e "bar" --recurse-submodules HEAD^ >actual &&
+	git grep -e "(3|4)" --recurse-submodules HEAD^ >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep tree HEAD^^' '
 	cat >expect <<-\EOF &&
-	HEAD^^:a:foobar
-	HEAD^^:b/b:bar
+	HEAD^^:a:(1|2)d(3|4)
+	HEAD^^:b/b:(3|4)
 	EOF
 
-	git grep -e "bar" --recurse-submodules HEAD^^ >actual &&
+	git grep -e "(3|4)" --recurse-submodules HEAD^^ >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep tree and pathspecs' '
 	cat >expect <<-\EOF &&
-	HEAD:submodule/a:foobar
-	HEAD:submodule/sub/a:foobar
+	HEAD:submodule/a:(1|2)d(3|4)
+	HEAD:submodule/sub/a:(1|2)d(3|4)
 	EOF
 
-	git grep -e "bar" --recurse-submodules HEAD -- submodule >actual &&
+	git grep -e "(3|4)" --recurse-submodules HEAD -- submodule >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep tree and pathspecs' '
 	cat >expect <<-\EOF &&
-	HEAD:submodule/a:foobar
-	HEAD:submodule/sub/a:foobar
+	HEAD:submodule/a:(1|2)d(3|4)
+	HEAD:submodule/sub/a:(1|2)d(3|4)
 	EOF
 
-	git grep -e "bar" --recurse-submodules HEAD -- "submodule*a" >actual &&
+	git grep -e "(3|4)" --recurse-submodules HEAD -- "submodule*a" >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep tree and more pathspecs' '
 	cat >expect <<-\EOF &&
-	HEAD:submodule/a:foobar
+	HEAD:submodule/a:(1|2)d(3|4)
 	EOF
 
-	git grep -e "bar" --recurse-submodules HEAD -- "submodul?/a" >actual &&
+	git grep -e "(3|4)" --recurse-submodules HEAD -- "submodul?/a" >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep tree and more pathspecs' '
 	cat >expect <<-\EOF &&
-	HEAD:submodule/sub/a:foobar
+	HEAD:submodule/sub/a:(1|2)d(3|4)
 	EOF
 
-	git grep -e "bar" --recurse-submodules HEAD -- "submodul*/sub/a" >actual &&
+	git grep -e "(3|4)" --recurse-submodules HEAD -- "submodul*/sub/a" >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success !MINGW 'grep recurse submodule colon in name' '
 	git init parent &&
 	test_when_finished "rm -rf parent" &&
-	echo "foobar" >"parent/fi:le" &&
+	echo "(1|2)d(3|4)" >"parent/fi:le" &&
 	git -C parent add "fi:le" &&
 	git -C parent commit -m "add fi:le" &&
 
 	git init "su:b" &&
 	test_when_finished "rm -rf su:b" &&
-	echo "foobar" >"su:b/fi:le" &&
+	echo "(1|2)d(3|4)" >"su:b/fi:le" &&
 	git -C "su:b" add "fi:le" &&
 	git -C "su:b" commit -m "add fi:le" &&
 
@@ -172,30 +172,30 @@ test_expect_success !MINGW 'grep recurse submodule colon in name' '
 	git -C parent commit -m "add submodule" &&
 
 	cat >expect <<-\EOF &&
-	fi:le:foobar
-	su:b/fi:le:foobar
+	fi:le:(1|2)d(3|4)
+	su:b/fi:le:(1|2)d(3|4)
 	EOF
-	git -C parent grep -e "foobar" --recurse-submodules >actual &&
+	git -C parent grep -e "(1|2)d(3|4)" --recurse-submodules >actual &&
 	test_cmp expect actual &&
 
 	cat >expect <<-\EOF &&
-	HEAD:fi:le:foobar
-	HEAD:su:b/fi:le:foobar
+	HEAD:fi:le:(1|2)d(3|4)
+	HEAD:su:b/fi:le:(1|2)d(3|4)
 	EOF
-	git -C parent grep -e "foobar" --recurse-submodules HEAD >actual &&
+	git -C parent grep -e "(1|2)d(3|4)" --recurse-submodules HEAD >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep history with moved submoules' '
 	git init parent &&
 	test_when_finished "rm -rf parent" &&
-	echo "foobar" >parent/file &&
+	echo "(1|2)d(3|4)" >parent/file &&
 	git -C parent add file &&
 	git -C parent commit -m "add file" &&
 
 	git init sub &&
 	test_when_finished "rm -rf sub" &&
-	echo "foobar" >sub/file &&
+	echo "(1|2)d(3|4)" >sub/file &&
 	git -C sub add file &&
 	git -C sub commit -m "add file" &&
 
@@ -203,82 +203,82 @@ test_expect_success 'grep history with moved submoules' '
 	git -C parent commit -m "add submodule" &&
 
 	cat >expect <<-\EOF &&
-	dir/sub/file:foobar
-	file:foobar
+	dir/sub/file:(1|2)d(3|4)
+	file:(1|2)d(3|4)
 	EOF
-	git -C parent grep -e "foobar" --recurse-submodules >actual &&
+	git -C parent grep -e "(1|2)d(3|4)" --recurse-submodules >actual &&
 	test_cmp expect actual &&
 
 	git -C parent mv dir/sub sub-moved &&
 	git -C parent commit -m "moved submodule" &&
 
 	cat >expect <<-\EOF &&
-	file:foobar
-	sub-moved/file:foobar
+	file:(1|2)d(3|4)
+	sub-moved/file:(1|2)d(3|4)
 	EOF
-	git -C parent grep -e "foobar" --recurse-submodules >actual &&
+	git -C parent grep -e "(1|2)d(3|4)" --recurse-submodules >actual &&
 	test_cmp expect actual &&
 
 	cat >expect <<-\EOF &&
-	HEAD^:dir/sub/file:foobar
-	HEAD^:file:foobar
+	HEAD^:dir/sub/file:(1|2)d(3|4)
+	HEAD^:file:(1|2)d(3|4)
 	EOF
-	git -C parent grep -e "foobar" --recurse-submodules HEAD^ >actual &&
+	git -C parent grep -e "(1|2)d(3|4)" --recurse-submodules HEAD^ >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep using relative path' '
 	test_when_finished "rm -rf parent sub" &&
 	git init sub &&
-	echo "foobar" >sub/file &&
+	echo "(1|2)d(3|4)" >sub/file &&
 	git -C sub add file &&
 	git -C sub commit -m "add file" &&
 
 	git init parent &&
-	echo "foobar" >parent/file &&
+	echo "(1|2)d(3|4)" >parent/file &&
 	git -C parent add file &&
 	mkdir parent/src &&
-	echo "foobar" >parent/src/file2 &&
+	echo "(1|2)d(3|4)" >parent/src/file2 &&
 	git -C parent add src/file2 &&
 	git -C parent submodule add ../sub &&
 	git -C parent commit -m "add files and submodule" &&
 
 	# From top works
 	cat >expect <<-\EOF &&
-	file:foobar
-	src/file2:foobar
-	sub/file:foobar
+	file:(1|2)d(3|4)
+	src/file2:(1|2)d(3|4)
+	sub/file:(1|2)d(3|4)
 	EOF
-	git -C parent grep --recurse-submodules -e "foobar" >actual &&
+	git -C parent grep --recurse-submodules -e "(1|2)d(3|4)" >actual &&
 	test_cmp expect actual &&
 
 	# Relative path to top
 	cat >expect <<-\EOF &&
-	../file:foobar
-	file2:foobar
-	../sub/file:foobar
+	../file:(1|2)d(3|4)
+	file2:(1|2)d(3|4)
+	../sub/file:(1|2)d(3|4)
 	EOF
-	git -C parent/src grep --recurse-submodules -e "foobar" -- .. >actual &&
+	git -C parent/src grep --recurse-submodules -e "(1|2)d(3|4)" -- .. >actual &&
 	test_cmp expect actual &&
 
 	# Relative path to submodule
 	cat >expect <<-\EOF &&
-	../sub/file:foobar
+	../sub/file:(1|2)d(3|4)
 	EOF
-	git -C parent/src grep --recurse-submodules -e "foobar" -- ../sub >actual &&
+	git -C parent/src grep --recurse-submodules -e "(1|2)d(3|4)" -- ../sub >actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'grep from a subdir' '
 	test_when_finished "rm -rf parent sub" &&
 	git init sub &&
-	echo "foobar" >sub/file &&
+	echo "(1|2)d(3|4)" >sub/file &&
 	git -C sub add file &&
 	git -C sub commit -m "add file" &&
 
 	git init parent &&
 	mkdir parent/src &&
-	echo "foobar" >parent/src/file &&
+	echo "(1|2)d(3|4)" >parent/src/file &&
 	git -C parent add src/file &&
 	git -C parent submodule add ../sub src/sub &&
 	git -C parent submodule add ../sub sub &&
@@ -286,19 +286,19 @@ test_expect_success 'grep from a subdir' '
 
 	# Verify grep from root works
 	cat >expect <<-\EOF &&
-	src/file:foobar
-	src/sub/file:foobar
-	sub/file:foobar
+	src/file:(1|2)d(3|4)
+	src/sub/file:(1|2)d(3|4)
+	sub/file:(1|2)d(3|4)
 	EOF
-	git -C parent grep --recurse-submodules -e "foobar" >actual &&
+	git -C parent grep --recurse-submodules -e "(1|2)d(3|4)" >actual &&
 	test_cmp expect actual &&
 
 	# Verify grep from a subdir works
 	cat >expect <<-\EOF &&
-	file:foobar
-	sub/file:foobar
+	file:(1|2)d(3|4)
+	sub/file:(1|2)d(3|4)
 	EOF
-	git -C parent/src grep --recurse-submodules -e "foobar" >actual &&
+	git -C parent/src grep --recurse-submodules -e "(1|2)d(3|4)" >actual &&
 	test_cmp expect actual
 '
 

diff --git a/t/t7814-grep-recurse-submodules.sh b/t/t7814-grep-recurse-submodules.sh
index 3c580b38ba..ef658b7899 100755
--- a/t/t7814-grep-recurse-submodules.sh
+++ b/t/t7814-grep-recurse-submodules.sh
@@ -313,4 +313,53 @@ test_incompatible_with_recurse_submodules ()
 test_incompatible_with_recurse_submodules --untracked
 test_incompatible_with_recurse_submodules --no-index
 
+test_expect_success 'grep --recurse-submodules should pass the pattern type along' '
+	# Fixed
+	test_must_fail git grep -F --recurse-submodules -e "(.|.)[\d]" &&
+	test_must_fail git -c grep.patternType=fixed grep --recurse-submodules -e "(.|.)[\d]" &&
+
+	# Basic
+	git grep -G --recurse-submodules -e "(.|.)[\d]" >actual &&
+	cat >expect <<-\EOF &&
+	a:(1|2)d(3|4)
+	submodule/a:(1|2)d(3|4)
+	submodule/sub/a:(1|2)d(3|4)
+	EOF
+	test_cmp expect actual &&
+	git -c grep.patternType=basic grep --recurse-submodules -e "(.|.)[\d]" >actual &&
+	test_cmp expect actual &&
+
+	# Extended
+	git grep -E --recurse-submodules -e "(.|.)[\d]" >actual &&
+	cat >expect <<-\EOF &&
+	.gitmodules:[submodule "submodule"]
+	.gitmodules:	path = submodule
+	.gitmodules:	url = ./submodule
+	a:(1|2)d(3|4)
+	submodule/.gitmodules:[submodule "sub"]
+	submodule/a:(1|2)d(3|4)
+	submodule/sub/a:(1|2)d(3|4)
+	EOF
+	test_cmp expect actual &&
+	git -c grep.patternType=extended grep --recurse-submodules -e "(.|.)[\d]" >actual &&
+	test_cmp expect actual &&
+	git -c grep.extendedRegexp=true grep --recurse-submodules -e "(.|.)[\d]" >actual &&
+	test_cmp expect actual &&
+
+	# Perl
+	if test_have_prereq PCRE
+	then
+		git grep -P --recurse-submodules -e "(.|.)[\d]" >actual &&
+		cat >expect <<-\EOF &&
+		a:(1|2)d(3|4)
+		b/b:(3|4)
+		submodule/a:(1|2)d(3|4)
+		submodule/sub/a:(1|2)d(3|4)
+		EOF
+		test_cmp expect actual &&
+		git -c grep.patternType=perl grep --recurse-submodules -e "(.|.)[\d]" >actual &&
+		test_cmp expect actual
+	fi
+'
+
 test_done

diff --git a/t/t7812-grep-icase-non-ascii.sh b/t/t7812-grep-icase-non-ascii.sh
index 04a61cb8e0..969e7c0dda 100755
--- a/t/t7812-grep-icase-non-ascii.sh
+++ b/t/t7812-grep-icase-non-ascii.sh
@@ -36,29 +36,14 @@ test_expect_success GETTEXT_LOCALE,PCRE 'grep pcre utf-8 string with "+"' '
 '
 
 test_expect_success REGEX_LOCALE 'grep literal string, with -F' '
-	git grep --debug -i -F "TILRAUN: Halló Heimur!"  2>&1 >/dev/null |
-		 grep fixed >debug1 &&
-	test_write_lines "fixed TILRAUN: Halló Heimur!" >expect1 &&
-	test_cmp expect1 debug1 &&
-
-	git grep --debug -i -F "TILRAUN: HALLÓ HEIMUR!"  2>&1 >/dev/null |
-		 grep fixed >debug2 &&
-	test_write_lines "fixed TILRAUN: HALLÓ HEIMUR!" >expect2 &&
-	test_cmp expect2 debug2
+	git grep -i -F "TILRAUN: Halló Heimur!" &&
+	git grep -i -F "TILRAUN: HALLÓ HEIMUR!"
 '
 
 test_expect_success REGEX_LOCALE 'grep string with regex, with -F' '
-	test_write_lines "^*TILR^AUN:.* \\Halló \$He[]imur!\$" >file &&
-
-	git grep --debug -i -F "^*TILR^AUN:.* \\Halló \$He[]imur!\$" 2>&1 >/dev/null |
-		 grep fixed >debug1 &&
-	test_write_lines "fixed \\^*TILR^AUN:\\.\\* \\\\Halló \$He\\[]imur!\\\$" >expect1 &&
-	test_cmp expect1 debug1 &&
-
-	git grep --debug -i -F "^*TILR^AUN:.* \\HALLÓ \$HE[]IMUR!\$"  2>&1 >/dev/null |
-		 grep fixed >debug2 &&
-	test_write_lines "fixed \\^*TILR^AUN:\\.\\* \\\\HALLÓ \$HE\\[]IMUR!\\\$" >expect2 &&
-	test_cmp expect2 debug2
+	test_write_lines "TILRAUN: Halló Heimur [abc]!" >file3 &&
+	git add file3 &&
+	git grep --debug -i -F "TILRAUN: Halló Heimur [abc]!" file3
 '
 
 test_expect_success REGEX_LOCALE 'pickaxe -i on non-ascii' '

diff --git a/t/t7008-grep-binary.sh b/t/t7008-grep-binary.sh
index 6c1952eafa..1afba6cee9 100755
--- a/t/t7008-grep-binary.sh
+++ b/t/t7008-grep-binary.sh
@@ -28,7 +28,7 @@ nul_match() {
 }
 
 test_expect_success 'setup' "
-	echo 'binaryQfile' | q_to_nul >a &&
+	echo 'binaryQfileQm[*]cQ*æQð' | q_to_nul >a &&
 	git add a &&
 	git commit -m.
 "
@@ -162,7 +162,7 @@ test_expect_success 'grep does not honor textconv' '
 '
 
 test_expect_success 'grep --textconv honors textconv' '
-	echo "a:binaryQfile" >expect &&
+	echo "a:binaryQfileQm[*]cQ*æQð" >expect &&
 	git grep --textconv Qfile >actual &&
 	test_cmp expect actual
 '
@@ -172,7 +172,7 @@ test_expect_success 'grep --no-textconv does not honor textconv' '
 '
 
 test_expect_success 'grep --textconv blob honors textconv' '
-	echo "HEAD:a:binaryQfile" >expect &&
+	echo "HEAD:a:binaryQfileQm[*]cQ*æQð" >expect &&
 	git grep --textconv Qfile HEAD:a >actual &&
 	test_cmp expect actual
 '

diff --git a/t/t7008-grep-binary.sh b/t/t7008-grep-binary.sh
index 1afba6cee9..ba3db06501 100755
--- a/t/t7008-grep-binary.sh
+++ b/t/t7008-grep-binary.sh
@@ -22,6 +22,18 @@ nul_match() {
 			printf '$pattern' | q_to_nul >f &&
 			test_must_fail git grep -f f $flags a
 		"
+	elif test $status = "T1"
+	then
+		test_expect_failure "git grep -f f $flags '$pattern_human' a" "
+			printf '$pattern' | q_to_nul >f &&
+			git grep -f f $flags a
+		"
+	elif test $status = "T0"
+	then
+		test_expect_failure "git grep -f f $flags '$pattern_human' a" "
+			printf '$pattern' | q_to_nul >f &&
+			test_must_fail git grep -f f $flags a
+		"
 	else
 		test_expect_success "PANIC: Test framework error. Unknown status $status" 'false'
 	fi
@@ -98,6 +110,65 @@ nul_match 1 '-Fi' 'YQf'
 nul_match 0 '-Fi' 'YQx'
 nul_match 1 '' 'yQf'
 nul_match 0 '' 'yQx'
+nul_match 1 '' 'æQð'
+nul_match 1 '-F' 'eQm[*]c'
+nul_match 1 '-Fi' 'EQM[*]C'
+
+# Regex patterns that would match but shouldn't with -F
+nul_match 0 '-F' 'yQ[f]'
+nul_match 0 '-F' '[y]Qf'
+nul_match 0 '-Fi' 'YQ[F]'
+nul_match 0 '-Fi' '[Y]QF'
+nul_match 0 '-F' 'æQ[ð]'
+nul_match 0 '-F' '[æ]Qð'
+nul_match 0 '-Fi' 'ÆQ[Ð]'
+nul_match 0 '-Fi' '[Æ]QÐ'
+
+# kwset is disabled on -i & non-ASCII. No way to match non-ASCII \0
+# patterns case-insensitively.
+nul_match T1 '-i' 'ÆQÐ'
+
+# \0 implicitly disables regexes. This is an undocumented internal
+# limitation.
+nul_match T1 '' 'yQ[f]'
+nul_match T1 '' '[y]Qf'
+nul_match T1 '-i' 'YQ[F]'
+nul_match T1 '-i' '[Y]Qf'
+nul_match T1 '' 'æQ[ð]'
+nul_match T1 '' '[æ]Qð'
+nul_match T1 '-i' 'ÆQ[Ð]'
+
+# ... because of \0 implicitly disabling regexes regexes that
+# should/shouldn't match don't do the right thing.
+nul_match T1 '' 'eQm.*cQ'
+nul_match T1 '-i' 'EQM.*cQ'
+nul_match T0 '' 'eQm[*]c'
+nul_match T0 '-i' 'EQM[*]C'
+
+# Due to the REG_STARTEND extension when kwset() is disabled on -i &
+# non-ASCII the string will be matched in its entirety, but the
+# pattern will be cut off at the first \0.
+nul_match 0 '-i' 'NOMATCHQð'
+nul_match T0 '-i' '[Æ]QNOMATCH'
+nul_match T0 '-i' '[æ]QNOMATCH'
+# Matches, but for the wrong reasons, just stops at [æ]
+nul_match 1 '-i' '[Æ]Qð'
+nul_match 1 '-i' '[æ]Qð'
+
+# Ensure that the matcher doesn't regress to something that stops at
+# \0
+nul_match 0 '-F' 'yQ[f]'
+nul_match 0 '-Fi' 'YQ[F]'
+nul_match 0 '' 'yQNOMATCH'
+nul_match 0 '' 'QNOMATCH'
+nul_match 0 '-i' 'YQNOMATCH'
+nul_match 0 '-i' 'QNOMATCH'
+nul_match 0 '-F' 'æQ[ð]'
+nul_match 0 '-Fi' 'ÆQ[Ð]'
+nul_match 0 '' 'yQNÓMATCH'
+nul_match 0 '' 'QNÓMATCH'
+nul_match 0 '-i' 'YQNÓMATCH'
+nul_match 0 '-i' 'QNÓMATCH'
 
 test_expect_success 'grep respects binary diff attribute' '
 	echo text >t &&

Makefile, t/perf/README, t/perf/run

diff --git a/Makefile b/Makefile
index eedadb8056..d1587452f1 100644
--- a/Makefile
+++ b/Makefile
@@ -2272,6 +2272,9 @@ endif
 ifdef GIT_PERF_MAKE_OPTS
 	@echo GIT_PERF_MAKE_OPTS=\''$(subst ','\'',$(subst ','\'',$(GIT_PERF_MAKE_OPTS)))'\' >>$@+
 endif
+ifdef GIT_PERF_MAKE_COMMAND
+	@echo GIT_PERF_MAKE_COMMAND=\''$(subst ','\'',$(subst ','\'',$(GIT_PERF_MAKE_COMMAND)))'\' >>$@+
+endif
 ifdef GIT_INTEROP_MAKE_OPTS
 	@echo GIT_INTEROP_MAKE_OPTS=\''$(subst ','\'',$(subst ','\'',$(GIT_INTEROP_MAKE_OPTS)))'\' >>$@+
 endif
diff --git a/t/perf/README b/t/perf/README
index 49ea4349be..b3d95042a8 100644
--- a/t/perf/README
+++ b/t/perf/README
@@ -60,8 +60,23 @@ You can set the following variables (also in your config.mak):
 
     GIT_PERF_MAKE_OPTS
 	Options to use when automatically building a git tree for
-	performance testing.  E.g., -j6 would be useful.
-
+	performance testing. E.g., -j6 would be useful. Passed
+	directly to make as "make $GIT_PERF_MAKE_OPTS".
+
+    GIT_PERF_MAKE_COMMAND
+	An arbitrary command that'll be run in place of the make
+	command, if set the GIT_PERF_MAKE_OPTS variable is
+	ignored. Useful in cases where source tree changes might
+	require issuing a different make command to different
+	revisions.
+
+	This can be (ab)used to monkeypatch or otherwise change the
+	tree about to be built. Note that the build directory can be
+	re-used for subsequent runs so the make command might get
+	executed multiple times on the same tree, but don't count on
+	any of that, that's an implementation detail that might change
+	in the future.
+ 
     GIT_PERF_REPO
     GIT_PERF_LARGE_REPO
 	Repositories to copy for the performance tests.  The normal
diff --git a/t/perf/run b/t/perf/run
index c788d713ae..b61024a830 100755
--- a/t/perf/run
+++ b/t/perf/run
@@ -37,8 +37,15 @@ build_git_rev () {
 			cp "../../$config" "build/$rev/"
 		fi
 	done
-	(cd build/$rev && make $GIT_PERF_MAKE_OPTS) ||
-	die "failed to build revision '$mydir'"
+	(
+		cd build/$rev &&
+		if test -n "$GIT_PERF_MAKE_COMMAND"
+		then
+			sh -c "$GIT_PERF_MAKE_COMMAND"
+		else
+			make $GIT_PERF_MAKE_OPTS
+		fi
+	) || die "failed to build revision '$mydir'"
 }
 
 run_dirs_helper () {

diff --git a/t/t7008-grep-binary.sh b/t/t7008-grep-binary.sh
index 9c9c378119..6c1952eafa 100755
--- a/t/t7008-grep-binary.sh
+++ b/t/t7008-grep-binary.sh
@@ -4,6 +4,29 @@ test_description='git grep in binary files'
 
 . ./test-lib.sh
 
+nul_match() {
+	status=$1
+	flags=$2
+	pattern=$3
+	pattern_human=$(echo $pattern | sed 's/Q/<NUL>/g')
+
+	if test $status = "1"
+	then
+		test_expect_success "git grep -f f $flags '$pattern_human' a" "
+			printf '$pattern' | q_to_nul >f &&
+			git grep -f f $flags a
+		"
+	elif test $status = "0"
+	then
+		test_expect_success "git grep -f f $flags '$pattern_human' a" "
+			printf '$pattern' | q_to_nul >f &&
+			test_must_fail git grep -f f $flags a
+		"
+	else
+		test_expect_success "PANIC: Test framework error. Unknown status $status" 'false'
+	fi
+}
+
 test_expect_success 'setup' "
 	echo 'binaryQfile' | q_to_nul >a &&
 	git add a &&
@@ -69,35 +92,12 @@ test_expect_failure 'git grep .fi a' '
 	git grep .fi a
 '
 
-test_expect_success 'git grep -F y<NUL>f a' "
-	printf 'yQf' | q_to_nul >f &&
-	git grep -f f -F a
-"
-
-test_expect_success 'git grep -F y<NUL>x a' "
-	printf 'yQx' | q_to_nul >f &&
-	test_must_fail git grep -f f -F a
-"
-
-test_expect_success 'git grep -Fi Y<NUL>f a' "
-	printf 'YQf' | q_to_nul >f &&
-	git grep -f f -Fi a
-"
-
-test_expect_success 'git grep -Fi Y<NUL>x a' "
-	printf 'YQx' | q_to_nul >f &&
-	test_must_fail git grep -f f -Fi a
-"
-
-test_expect_success 'git grep y<NUL>f a' "
-	printf 'yQf' | q_to_nul >f &&
-	git grep -f f a
-"
-
-test_expect_success 'git grep y<NUL>x a' "
-	printf 'yQx' | q_to_nul >f &&
-	test_must_fail git grep -f f a
-"
+nul_match 1 '-F' 'yQf'
+nul_match 0 '-F' 'yQx'
+nul_match 1 '-Fi' 'YQf'
+nul_match 0 '-Fi' 'YQx'
+nul_match 1 '' 'yQf'
+nul_match 0 '' 'yQx'
 
 test_expect_success 'grep respects binary diff attribute' '
 	echo text >t &&

diff --git a/t/perf/run b/t/perf/run
index b61024a830..beb4acc0e4 100755
--- a/t/perf/run
+++ b/t/perf/run
@@ -24,6 +24,7 @@ run_one_dir () {
 
 unpack_git_rev () {
 	rev=$1
+	echo "=== Unpacking $rev in build/$rev ==="
 	mkdir -p build/$rev
 	(cd "$(git rev-parse --show-cdup)" && git archive --format=tar $rev) |
 	(cd build/$rev && tar x)
@@ -37,6 +38,7 @@ build_git_rev () {
 			cp "../../$config" "build/$rev/"
 		fi
 	done
+	echo "=== Building $rev ==="
 	(
 		cd build/$rev &&
 		if test -n "$GIT_PERF_MAKE_COMMAND"

diff --git a/t/perf/p7820-grep-engines.sh b/t/perf/p7820-grep-engines.sh
new file mode 100755
index 0000000000..c99979990e
--- /dev/null
+++ b/t/perf/p7820-grep-engines.sh
@@ -0,0 +1,35 @@
+#!/bin/sh
+
+test_description="Comparison of git-grep's regex engines"
+
+. ./perf-lib.sh
+
+test_perf_large_repo
+test_checkout_worktree
+
+for pattern in \
+	'how.to' \
+	'^how to' \
+	'[how] to' \
+	'\(e.t[^ ]*\|v.ry\) rare' \
+	'm\(ú\|u\)ult.b\(æ\|y\)te'
+do
+	for engine in basic extended perl
+	do
+		if test $engine != "basic"
+		then
+			# Poor man's basic -> extended converter.
+			pattern=$(echo $pattern | sed 's/\\//g')
+		fi
+		test_perf "$engine grep $pattern" "
+			git -c grep.patternType=$engine grep -- '$pattern' >'out.$engine' || :
+		"
+	done
+
+	test_expect_success "assert that all engines found the same for $pattern" "
+		test_cmp 'out.basic' 'out.extended' &&
+		test_cmp 'out.basic' 'out.perl'
+	"
+done
+
+test_done

diff --git a/builtin/grep.c b/builtin/grep.c
index 3ffb5b4e81..1c0adb30f3 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -495,6 +495,12 @@ static void compile_submodule_options(const struct grep_opt *opt,
 		break;
 	case GREP_PATTERN_TYPE_UNSPECIFIED:
 		break;
+	default:
+		/*
+		 * -Wswitch doesn't catch this due to casting &
+		 * -Wswitch-default is too noisy.
+		 */
+		die("BUG: Added a new grep pattern type without updating switch statement");
 	}
 
 	for (pattern = opt->pattern_list; pattern != NULL;

diff --git a/t/perf/p7821-grep-engines-fixed.sh b/t/perf/p7821-grep-engines-fixed.sh
new file mode 100755
index 0000000000..66a78d225d
--- /dev/null
+++ b/t/perf/p7821-grep-engines-fixed.sh
@@ -0,0 +1,27 @@
+#!/bin/sh
+
+test_description="Comparison of fixed string grep under git-grep's regex engines"
+
+. ./perf-lib.sh
+
+test_perf_large_repo
+test_checkout_worktree
+
+for args in 'int' '-i int' 'æ' '-i æ'
+do
+	for engine in fixed basic extended perl
+	do
+		test_perf "$engine grep $args" "
+			git -c grep.patternType=$engine grep $args >'out.$engine.$args' || :
+		"
+	done
+
+	test_expect_success "assert that all engines found the same for $args" "
+		test_cmp 'out.fixed.$args' 'out.basic.$args' &&
+		test_cmp 'out.fixed.$args' 'out.extended.$args' &&
+		test_cmp 'out.fixed.$args' 'out.extended.$args' &&
+		test_cmp 'out.fixed.$args' 'out.perl.$args'
+	"
+done
+
+test_done

diff --git a/grep.c b/grep.c
index 47cee45067..59ae7809f2 100644
--- a/grep.c
+++ b/grep.c
@@ -197,7 +197,6 @@ static void grep_set_pattern_type_option(enum grep_pattern_type pattern_type, st
 	case GREP_PATTERN_TYPE_PCRE:
 		opt->fixed = 0;
 		opt->pcre = 1;
-		opt->regflags &= ~REG_EXTENDED;
 		break;
 	}
 }

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);

diff --git a/grep.c b/grep.c
index bf6c2494fd..27de615209 100644
--- a/grep.c
+++ b/grep.c
@@ -394,12 +394,6 @@ static int is_fixed(const char *s, size_t len)
 {
 	size_t i;
 
-	/* regcomp cannot accept patterns with NULs so we
-	 * consider any pattern containing a NUL fixed.
-	 */
-	if (memchr(s, 0, len))
-		return 1;
-
 	for (i = 0; i < len; i++) {
 		if (is_regex_special(s[i]))
 			return 0;
@@ -408,6 +402,17 @@ static int is_fixed(const char *s, size_t len)
 	return 1;
 }
 
+static int has_null(const char *s, size_t len)
+{
+	/* regcomp cannot accept patterns with NULs so when using it
+	 * we consider any pattern containing a NUL fixed.
+	 */
+	if (memchr(s, 0, len))
+		return 1;
+
+	return 0;
+}
+
 static void compile_fixed_regexp(struct grep_pat *p, struct grep_opt *opt)
 {
 	struct strbuf sb = STRBUF_INIT;
@@ -451,7 +456,7 @@ static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
 	 * simple string match using kws.  p->fixed tells us if we
 	 * want to use kws.
 	 */
-	if (opt->fixed || is_fixed(p->pattern, p->patternlen))
+	if (opt->fixed || has_null(p->pattern, p->patternlen) || is_fixed(p->pattern, p->patternlen))
 		p->fixed = !icase || ascii_only;
 	else
 		p->fixed = 0;

Makefile, grep.c, grep.h, t/test-lib.sh

diff --git a/Makefile b/Makefile
index d1587452f1..374fbc7e58 100644
--- a/Makefile
+++ b/Makefile
@@ -1088,7 +1088,7 @@ ifdef NO_LIBGEN_H
 endif
 
 ifdef USE_LIBPCRE
-	BASIC_CFLAGS += -DUSE_LIBPCRE
+	BASIC_CFLAGS += -DUSE_LIBPCRE1
 	ifdef LIBPCREDIR
 		BASIC_CFLAGS += -I$(LIBPCREDIR)/include
 		EXTLIBS += -L$(LIBPCREDIR)/$(lib) $(CC_LD_DYNPATH)$(LIBPCREDIR)/$(lib)
@@ -2240,7 +2240,7 @@ GIT-BUILD-OPTIONS: FORCE
 	@echo TAR=\''$(subst ','\'',$(subst ','\'',$(TAR)))'\' >>$@+
 	@echo NO_CURL=\''$(subst ','\'',$(subst ','\'',$(NO_CURL)))'\' >>$@+
 	@echo NO_EXPAT=\''$(subst ','\'',$(subst ','\'',$(NO_EXPAT)))'\' >>$@+
-	@echo USE_LIBPCRE=\''$(subst ','\'',$(subst ','\'',$(USE_LIBPCRE)))'\' >>$@+
+	@echo USE_LIBPCRE1=\''$(subst ','\'',$(subst ','\'',$(USE_LIBPCRE)))'\' >>$@+
 	@echo NO_PERL=\''$(subst ','\'',$(subst ','\'',$(NO_PERL)))'\' >>$@+
 	@echo NO_PYTHON=\''$(subst ','\'',$(subst ','\'',$(NO_PYTHON)))'\' >>$@+
 	@echo NO_UNIX_SOCKETS=\''$(subst ','\'',$(subst ','\'',$(NO_UNIX_SOCKETS)))'\' >>$@+
diff --git a/grep.c b/grep.c
index 27de615209..0977cac723 100644
--- a/grep.c
+++ b/grep.c
@@ -321,7 +321,7 @@ static NORETURN void compile_regexp_failed(const struct grep_pat *p,
 	die("%s'%s': %s", where, p->pattern, error);
 }
 
-#ifdef USE_LIBPCRE
+#ifdef USE_LIBPCRE1
 static void compile_pcre_regexp(struct grep_pat *p, const struct grep_opt *opt)
 {
 	const char *error;
@@ -373,7 +373,7 @@ static void free_pcre_regexp(struct grep_pat *p)
 	pcre_free(p->pcre_extra_info);
 	pcre_free((void *)p->pcre_tables);
 }
-#else /* !USE_LIBPCRE */
+#else /* !USE_LIBPCRE1 */
 static void compile_pcre_regexp(struct grep_pat *p, const struct grep_opt *opt)
 {
 	die("cannot use Perl-compatible regexes when not compiled with USE_LIBPCRE");
@@ -388,7 +388,7 @@ static int pcrematch(struct grep_pat *p, const char *line, const char *eol,
 static void free_pcre_regexp(struct grep_pat *p)
 {
 }
-#endif /* !USE_LIBPCRE */
+#endif /* !USE_LIBPCRE1 */
 
 static int is_fixed(const char *s, size_t len)
 {
diff --git a/grep.h b/grep.h
index 267534ca24..073b0e4c92 100644
--- a/grep.h
+++ b/grep.h
@@ -1,7 +1,7 @@
 #ifndef GREP_H
 #define GREP_H
 #include "color.h"
-#ifdef USE_LIBPCRE
+#ifdef USE_LIBPCRE1
 #include <pcre.h>
 #else
 typedef int pcre;
diff --git a/t/test-lib.sh b/t/test-lib.sh
index 6abf1d1918..e5cfbcc36b 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -1010,7 +1010,7 @@ esac
 ( COLUMNS=1 && test $COLUMNS = 1 ) && test_set_prereq COLUMNS_CAN_BE_1
 test -z "$NO_PERL" && test_set_prereq PERL
 test -z "$NO_PYTHON" && test_set_prereq PYTHON
-test -n "$USE_LIBPCRE" && test_set_prereq PCRE
+test -n "$USE_LIBPCRE1" && test_set_prereq PCRE
 test -z "$NO_GETTEXT" && test_set_prereq GETTEXT
 
 # Can we rely on git's output in the C locale?

grep.c, grep.h

diff --git a/grep.c b/grep.c
index 0977cac723..4507765811 100644
--- a/grep.c
+++ b/grep.c
@@ -178,23 +178,23 @@ 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->pcre1 = 0;
 		break;
 
 	case GREP_PATTERN_TYPE_ERE:
 		opt->fixed = 0;
-		opt->pcre = 0;
+		opt->pcre1 = 0;
 		opt->regflags |= REG_EXTENDED;
 		break;
 
 	case GREP_PATTERN_TYPE_FIXED:
 		opt->fixed = 1;
-		opt->pcre = 0;
+		opt->pcre1 = 0;
 		break;
 
 	case GREP_PATTERN_TYPE_PCRE:
 		opt->fixed = 0;
-		opt->pcre = 1;
+		opt->pcre1 = 1;
 		break;
 	}
 }
@@ -322,7 +322,7 @@ static NORETURN void compile_regexp_failed(const struct grep_pat *p,
 }
 
 #ifdef USE_LIBPCRE1
-static void compile_pcre_regexp(struct grep_pat *p, const struct grep_opt *opt)
+static void compile_pcre1_regexp(struct grep_pat *p, const struct grep_opt *opt)
 {
 	const char *error;
 	int erroffset;
@@ -330,23 +330,23 @@ static void compile_pcre_regexp(struct grep_pat *p, const struct grep_opt *opt)
 
 	if (opt->ignore_case) {
 		if (has_non_ascii(p->pattern))
-			p->pcre_tables = pcre_maketables();
+			p->pcre1_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);
-	if (!p->pcre_regexp)
+	p->pcre1_regexp = pcre_compile(p->pattern, options, &error, &erroffset,
+				      p->pcre1_tables);
+	if (!p->pcre1_regexp)
 		compile_regexp_failed(p, error);
 
-	p->pcre_extra_info = pcre_study(p->pcre_regexp, 0, &error);
-	if (!p->pcre_extra_info && error)
+	p->pcre1_extra_info = pcre_study(p->pcre1_regexp, 0, &error);
+	if (!p->pcre1_extra_info && error)
 		die("%s", error);
 }
 
-static int pcrematch(struct grep_pat *p, const char *line, const char *eol,
+static int pcre1match(struct grep_pat *p, const char *line, const char *eol,
 		regmatch_t *match, int eflags)
 {
 	int ovector[30], ret, flags = 0;
@@ -354,7 +354,7 @@ static int pcrematch(struct grep_pat *p, const char *line, const char *eol,
 	if (eflags & REG_NOTBOL)
 		flags |= PCRE_NOTBOL;
 
-	ret = pcre_exec(p->pcre_regexp, p->pcre_extra_info, line, eol - line,
+	ret = pcre_exec(p->pcre1_regexp, p->pcre1_extra_info, line, eol - line,
 			0, flags, ovector, ARRAY_SIZE(ovector));
 	if (ret < 0 && ret != PCRE_ERROR_NOMATCH)
 		die("pcre_exec failed with error code %d", ret);
@@ -367,25 +367,25 @@ static int pcrematch(struct grep_pat *p, const char *line, const char *eol,
 	return ret;
 }
 
-static void free_pcre_regexp(struct grep_pat *p)
+static void free_pcre1_regexp(struct grep_pat *p)
 {
-	pcre_free(p->pcre_regexp);
-	pcre_free(p->pcre_extra_info);
-	pcre_free((void *)p->pcre_tables);
+	pcre_free(p->pcre1_regexp);
+	pcre_free(p->pcre1_extra_info);
+	pcre_free((void *)p->pcre1_tables);
 }
 #else /* !USE_LIBPCRE1 */
-static void compile_pcre_regexp(struct grep_pat *p, const struct grep_opt *opt)
+static void compile_pcre1_regexp(struct grep_pat *p, const struct grep_opt *opt)
 {
 	die("cannot use Perl-compatible regexes when not compiled with USE_LIBPCRE");
 }
 
-static int pcrematch(struct grep_pat *p, const char *line, const char *eol,
+static int pcre1match(struct grep_pat *p, const char *line, const char *eol,
 		regmatch_t *match, int eflags)
 {
 	return 1;
 }
 
-static void free_pcre_regexp(struct grep_pat *p)
+static void free_pcre1_regexp(struct grep_pat *p)
 {
 }
 #endif /* !USE_LIBPCRE1 */
@@ -476,8 +476,8 @@ static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
 		return;
 	}
 
-	if (opt->pcre) {
-		compile_pcre_regexp(p, opt);
+	if (opt->pcre1) {
+		compile_pcre1_regexp(p, opt);
 		return;
 	}
 
@@ -833,8 +833,8 @@ void free_grep_patterns(struct grep_opt *opt)
 		case GREP_PATTERN_BODY:
 			if (p->kws)
 				kwsfree(p->kws);
-			else if (p->pcre_regexp)
-				free_pcre_regexp(p);
+			else if (p->pcre1_regexp)
+				free_pcre1_regexp(p);
 			else
 				regfree(&p->regexp);
 			free(p->pattern);
@@ -913,8 +913,8 @@ static int patmatch(struct grep_pat *p, char *line, char *eol,
 
 	if (p->fixed)
 		hit = !fixmatch(p, line, eol, match);
-	else if (p->pcre_regexp)
-		hit = !pcrematch(p, line, eol, match, eflags);
+	else if (p->pcre1_regexp)
+		hit = !pcre1match(p, line, eol, match, eflags);
 	else
 		hit = !regexec_buf(&p->regexp, line, eol - line, 1, match,
 				   eflags);
diff --git a/grep.h b/grep.h
index 073b0e4c92..38ac82b638 100644
--- a/grep.h
+++ b/grep.h
@@ -46,9 +46,9 @@ struct grep_pat {
 	size_t patternlen;
 	enum grep_header_field field;
 	regex_t regexp;
-	pcre *pcre_regexp;
-	pcre_extra *pcre_extra_info;
-	const unsigned char *pcre_tables;
+	pcre *pcre1_regexp;
+	pcre_extra *pcre1_extra_info;
+	const unsigned char *pcre1_tables;
 	kwset_t kws;
 	unsigned fixed:1;
 	unsigned ignore_case:1;
@@ -111,7 +111,7 @@ struct grep_opt {
 	int allow_textconv;
 	int extended;
 	int use_reflog_filter;
-	int pcre;
+	int pcre1;
 	int relative;
 	int pathname;
 	int null_following_name;

diff --git a/grep.c b/grep.c
index 4507765811..5c808f8971 100644
--- a/grep.c
+++ b/grep.c
@@ -321,6 +321,29 @@ static NORETURN void compile_regexp_failed(const struct grep_pat *p,
 	die("%s'%s': %s", where, p->pattern, error);
 }
 
+static int is_fixed(const char *s, size_t len)
+{
+	size_t i;
+
+	for (i = 0; i < len; i++) {
+		if (is_regex_special(s[i]))
+			return 0;
+	}
+
+	return 1;
+}
+
+static int has_null(const char *s, size_t len)
+{
+	/* regcomp cannot accept patterns with NULs so when using it
+	 * we consider any pattern containing a NUL fixed.
+	 */
+	if (memchr(s, 0, len))
+		return 1;
+
+	return 0;
+}
+
 #ifdef USE_LIBPCRE1
 static void compile_pcre1_regexp(struct grep_pat *p, const struct grep_opt *opt)
 {
@@ -390,29 +413,6 @@ static void free_pcre1_regexp(struct grep_pat *p)
 }
 #endif /* !USE_LIBPCRE1 */
 
-static int is_fixed(const char *s, size_t len)
-{
-	size_t i;
-
-	for (i = 0; i < len; i++) {
-		if (is_regex_special(s[i]))
-			return 0;
-	}
-
-	return 1;
-}
-
-static int has_null(const char *s, size_t len)
-{
-	/* regcomp cannot accept patterns with NULs so when using it
-	 * we consider any pattern containing a NUL fixed.
-	 */
-	if (memchr(s, 0, len))
-		return 1;
-
-	return 0;
-}
-
 static void compile_fixed_regexp(struct grep_pat *p, struct grep_opt *opt)
 {
 	struct strbuf sb = STRBUF_INIT;

Makefile, t/README, t/test-lib.sh

diff --git a/Makefile b/Makefile
index 374fbc7e58..a79274e5e6 100644
--- a/Makefile
+++ b/Makefile
@@ -2242,6 +2242,7 @@ GIT-BUILD-OPTIONS: FORCE
 	@echo NO_EXPAT=\''$(subst ','\'',$(subst ','\'',$(NO_EXPAT)))'\' >>$@+
 	@echo USE_LIBPCRE1=\''$(subst ','\'',$(subst ','\'',$(USE_LIBPCRE)))'\' >>$@+
 	@echo NO_PERL=\''$(subst ','\'',$(subst ','\'',$(NO_PERL)))'\' >>$@+
+	@echo NO_PTHREADS=\''$(subst ','\'',$(subst ','\'',$(NO_PTHREADS)))'\' >>$@+
 	@echo NO_PYTHON=\''$(subst ','\'',$(subst ','\'',$(NO_PYTHON)))'\' >>$@+
 	@echo NO_UNIX_SOCKETS=\''$(subst ','\'',$(subst ','\'',$(NO_UNIX_SOCKETS)))'\' >>$@+
 	@echo PAGER_ENV=\''$(subst ','\'',$(subst ','\'',$(PAGER_ENV)))'\' >>$@+
diff --git a/t/README b/t/README
index a90cb62583..2f95860369 100644
--- a/t/README
+++ b/t/README
@@ -817,6 +817,10 @@ use these, and "test_set_prereq" for how to define your own.
    Test is run on a filesystem which converts decomposed utf-8 (nfd)
    to precomposed utf-8 (nfc).
 
+ - PTHREADS
+
+   Git wasn't compiled with NO_PTHREADS=YesPlease.
+
 Tips for Writing Tests
 ----------------------
 
diff --git a/t/test-lib.sh b/t/test-lib.sh
index e5cfbcc36b..ab92c0ebaa 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -1009,6 +1009,7 @@ esac
 
 ( COLUMNS=1 && test $COLUMNS = 1 ) && test_set_prereq COLUMNS_CAN_BE_1
 test -z "$NO_PERL" && test_set_prereq PERL
+test -z "$NO_PTHREADS" && test_set_prereq PTHREADS
 test -z "$NO_PYTHON" && test_set_prereq PYTHON
 test -n "$USE_LIBPCRE1" && test_set_prereq PCRE
 test -z "$NO_GETTEXT" && test_set_prereq GETTEXT

diff --git a/t/t5300-pack-object.sh b/t/t5300-pack-object.sh
index 43a672c345..1629fa80b0 100755
--- a/t/t5300-pack-object.sh
+++ b/t/t5300-pack-object.sh
@@ -421,6 +421,40 @@ test_expect_success 'index-pack <pack> works in non-repo' '
 	test_path_is_file foo.idx
 '
 
+test_expect_success !PTHREADS,C_LOCALE_OUTPUT 'index-pack --threads=N or pack.threads=N warns when no pthreads' '
+	test_must_fail git index-pack --threads=2 2>err &&
+	grep ^warning: err >warnings &&
+	test_line_count = 1 warnings &&
+	grep -F "no threads support, ignoring --threads=2" err &&
+	test_must_fail git -c pack.threads=2 index-pack 2>err &&
+	grep ^warning: err >warnings &&
+	test_line_count = 1 warnings &&
+	grep -F "no threads support, ignoring pack.threads" err &&
+	test_must_fail git -c pack.threads=2 index-pack --threads=4 2>err &&
+	grep ^warning: err >warnings &&
+	test_line_count = 2 warnings &&
+	grep -F "no threads support, ignoring --threads=4" err &&
+	grep -F "no threads support, ignoring pack.threads" err
+'
+
+test_expect_success !PTHREADS,C_LOCALE_OUTPUT 'pack-objects --threads=N or pack.threads=N warns when no pthreads' '
+	git pack-objects --threads=2 --stdout --all </dev/null >/dev/null 2>err &&
+	grep ^warning: err >warnings &&
+	test_line_count = 1 warnings &&
+	grep -F "no threads support, ignoring --threads" err &&
+	git -c pack.threads=2 pack-objects --stdout --all </dev/null >/dev/null 2>err &&
+	cat err &&
+	grep ^warning: err >warnings &&
+	test_line_count = 2 warnings &&
+	grep -F "no threads support, ignoring --threads" err &&
+	grep -F "no threads support, ignoring pack.threads" err &&
+	git -c pack.threads=2 pack-objects --threads=4 --stdout --all </dev/null >/dev/null 2>err &&
+	grep ^warning: err >warnings &&
+	test_line_count = 2 warnings &&
+	grep -F "no threads support, ignoring --threads" err &&
+	grep -F "no threads support, ignoring pack.threads" err
+'
+
 #
 # WARNING!
 #

builtin/grep.c, t/t7810-grep.sh

diff --git a/builtin/grep.c b/builtin/grep.c
index 1c0adb30f3..f4e08dd2b6 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -289,6 +289,15 @@ static int grep_cmd_config(const char *var, const char *value, void *cb)
 		if (num_threads < 0)
 			die(_("invalid number of threads specified (%d) for %s"),
 			    num_threads, var);
+#ifdef NO_PTHREADS
+		else if (num_threads && num_threads != 1) {
+			/* TRANSLATORS: %s is the configuration
+			   variable for tweaking threads, currently
+			   grep.threads */
+			warning(_("no threads support, ignoring %s"), var);
+			num_threads = 0;
+		}
+#endif
 	}
 
 	return st;
@@ -1233,6 +1242,8 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 	else if (num_threads < 0)
 		die(_("invalid number of threads specified (%d)"), num_threads);
 #else
+	if (num_threads)
+		warning(_("no threads support, ignoring --threads"));
 	num_threads = 0;
 #endif
 
diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index 561709ef6a..f106387820 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -791,6 +791,24 @@ do
 	"
 done
 
+test_expect_success !PTHREADS,C_LOCALE_OUTPUT 'grep --threads=N or pack.threads=N warns when no pthreads' '
+	git grep --threads=2 Hello hello_world 2>err &&
+	grep ^warning: err >warnings &&
+	test_line_count = 1 warnings &&
+	grep -F "no threads support, ignoring --threads" err &&
+	git -c grep.threads=2 grep Hello hello_world 2>err &&
+	grep ^warning: err >warnings &&
+	test_line_count = 1 warnings &&
+	grep -F "no threads support, ignoring grep.threads" err &&
+	git -c grep.threads=2 grep --threads=4 Hello hello_world 2>err &&
+	grep ^warning: err >warnings &&
+	test_line_count = 2 warnings &&
+	grep -F "no threads support, ignoring --threads" err &&
+	grep -F "no threads support, ignoring grep.threads" err &&
+	git -c grep.threads=0 grep --threads=0 Hello hello_world 2>err &&
+	test_line_count = 0 err
+'
+
 test_expect_success 'grep from a subdirectory to search wider area (1)' '
 	mkdir -p s &&
 	(

Documentation/CodingGuidelines, bisect.c, builtin/blame.c, builtin/notes.c, builtin/remote.c, notes-utils.c, parse-options.c, ref-filter.c, sequencer.c

diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines
index a4191aa388..9fd7383819 100644
--- a/Documentation/CodingGuidelines
+++ b/Documentation/CodingGuidelines
@@ -256,12 +256,12 @@ For C programs:
 
    Note however that a comment that explains a translatable string to
    translators uses a convention of starting with a magic token
-   "TRANSLATORS: " immediately after the opening delimiter, even when
-   it spans multiple lines.  We do not add an asterisk at the beginning
-   of each line, either.  E.g.
+   "TRANSLATORS: ", e.g.
 
-	/* TRANSLATORS: here is a comment that explains the string
-	   to be translated, that follows immediately after it */
+	/*
+	 * TRANSLATORS: here is a comment that explains the string to
+	 * be translated, that follows immediately after it.
+	 */
 	_("Here is a translatable string explained by the above.");
 
  - Double negation is often harder to understand than no negation
diff --git a/bisect.c b/bisect.c
index 08c9fb7266..c5d5a2b64b 100644
--- a/bisect.c
+++ b/bisect.c
@@ -995,8 +995,10 @@ int bisect_next_all(const char *prefix, int no_checkout)
 
 	steps_msg = xstrfmt(Q_("(roughly %d step)", "(roughly %d steps)",
 		  steps), steps);
-	/* TRANSLATORS: the last %s will be replaced with
-	   "(roughly %d steps)" translation */
+	/*
+	 * TRANSLATORS: the last %s will be replaced with "(roughly %d
+	 * steps)" translation.
+	 */
 	printf(Q_("Bisecting: %d revision left to test after this %s\n",
 		  "Bisecting: %d revisions left to test after this %s\n",
 		  nr), nr, steps_msg);
diff --git a/builtin/blame.c b/builtin/blame.c
index 07506a3e45..ca9ebe40e7 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -2688,12 +2688,15 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
 		blame_date_width = sizeof("2006-10-19");
 		break;
 	case DATE_RELATIVE:
-		/* TRANSLATORS: This string is used to tell us the maximum
-		   display width for a relative timestamp in "git blame"
-		   output.  For C locale, "4 years, 11 months ago", which
-		   takes 22 places, is the longest among various forms of
-		   relative timestamps, but your language may need more or
-		   fewer display columns. */
+		/*
+		 * TRANSLATORS: This string is used to tell us the
+		 * maximum display width for a relative timestamp in
+		 * "git blame" output.  For C locale, "4 years, 11
+		 * months ago", which takes 22 places, is the longest
+		 * among various forms of relative timestamps, but
+		 * your language may need more or fewer display
+		 * columns.
+		 */
 		blame_date_width = utf8_strwidth(_("4 years, 11 months ago")) + 1; /* add the null */
 		break;
 	case DATE_NORMAL:
diff --git a/builtin/notes.c b/builtin/notes.c
index 7b891471c4..fb856e53b6 100644
--- a/builtin/notes.c
+++ b/builtin/notes.c
@@ -340,8 +340,10 @@ static struct notes_tree *init_notes_check(const char *subcommand,
 
 	ref = (flags & NOTES_INIT_WRITABLE) ? t->update_ref : t->ref;
 	if (!starts_with(ref, "refs/notes/"))
-		/* TRANSLATORS: the first %s will be replaced by a
-		   git notes command: 'add', 'merge', 'remove', etc.*/
+		/*
+		 * TRANSLATORS: the first %s will be replaced by a git
+		 * notes command: 'add', 'merge', 'remove', etc.
+		 */
 		die(_("refusing to %s notes in %s (outside of refs/notes/)"),
 		    subcommand, ref);
 	return t;
diff --git a/builtin/remote.c b/builtin/remote.c
index addf97ad29..9054e2858e 100644
--- a/builtin/remote.c
+++ b/builtin/remote.c
@@ -1151,8 +1151,11 @@ static int show(int argc, const char **argv)
 			url_nr = states.remote->url_nr;
 		}
 		for (i = 0; i < url_nr; i++)
-			/* TRANSLATORS: the colon ':' should align with
-			   the one in "  Fetch URL: %s" translation */
+			/*
+			 * TRANSLATORS: the colon ':' should align
+			 * with the one in " Fetch URL: %s"
+			 * translation.
+			 */
 			printf_ln(_("  Push  URL: %s"), url[i]);
 		if (!i)
 			printf_ln(_("  Push  URL: %s"), _("(no URL)"));
diff --git a/notes-utils.c b/notes-utils.c
index 24a33616a4..8f9ad7d1f8 100644
--- a/notes-utils.c
+++ b/notes-utils.c
@@ -132,8 +132,11 @@ struct notes_rewrite_cfg *init_copy_notes_for_rewrite(const char *cmd)
 		c->mode_from_env = 1;
 		c->combine = parse_combine_notes_fn(rewrite_mode_env);
 		if (!c->combine)
-			/* TRANSLATORS: The first %s is the name of the
-			   environment variable, the second %s is its value */
+			/*
+			 * TRANSLATORS: The first %s is the name of
+			 * the environment variable, the second %s is
+			 * its value.
+			 */
 			error(_("Bad %s value: '%s'"), GIT_NOTES_REWRITE_MODE_ENVIRONMENT,
 					rewrite_mode_env);
 	}
diff --git a/parse-options.c b/parse-options.c
index a23a1e67f0..e5ad34a2c3 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -589,8 +589,10 @@ static int usage_with_options_internal(struct parse_opt_ctx_t *ctx,
 
 	fprintf_ln(outfile, _("usage: %s"), _(*usagestr++));
 	while (*usagestr && **usagestr)
-		/* TRANSLATORS: the colon here should align with the
-		   one in "usage: %s" translation */
+		/*
+		 * TRANSLATORS: the colon here should align with the
+		 * one in "usage: %s" translation.
+		 */
 		fprintf_ln(outfile, _("   or: %s"), _(*usagestr++));
 	while (*usagestr) {
 		if (**usagestr)
diff --git a/ref-filter.c b/ref-filter.c
index 3a640448fd..5632841753 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -1251,13 +1251,17 @@ char *get_head_description(void)
 			    state.branch);
 	else if (state.detached_from) {
 		if (state.detached_at)
-			/* TRANSLATORS: make sure this matches
-			   "HEAD detached at " in wt-status.c */
+			/*
+			 * TRANSLATORS: make sure this matches "HEAD
+			 * detached at " in wt-status.c
+			 */
 			strbuf_addf(&desc, _("(HEAD detached at %s)"),
 				state.detached_from);
 		else
-			/* TRANSLATORS: make sure this matches
-			   "HEAD detached from " in wt-status.c */
+			/*
+			 * TRANSLATORS: make sure this matches "HEAD
+			 * detached from " in wt-status.c
+			 */
 			strbuf_addf(&desc, _("(HEAD detached from %s)"),
 				state.detached_from);
 	}
diff --git a/sequencer.c b/sequencer.c
index 10c3b4ff81..b77f359ca2 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -464,7 +464,8 @@ static int do_recursive_merge(struct commit *base, struct commit *next,
 
 	if (active_cache_changed &&
 	    write_locked_index(&the_index, &index_lock, COMMIT_LOCK))
-		/* TRANSLATORS: %s will be "revert", "cherry-pick" or
+		/*
+		 * TRANSLATORS: %s will be "revert", "cherry-pick" or
 		 * "rebase -i".
 		 */
 		return error(_("%s: Unable to write new index file"),

builtin/pack-objects.c, t/t5300-pack-object.sh

diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 0fe35d1b5a..f1baf05dfe 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -2472,8 +2472,10 @@ static int git_pack_config(const char *k, const char *v, void *cb)
 			die("invalid number of threads specified (%d)",
 			    delta_search_threads);
 #ifdef NO_PTHREADS
-		if (delta_search_threads != 1)
+		if (delta_search_threads != 1) {
 			warning("no threads support, ignoring %s", k);
+			delta_search_threads = 0;
+		}
 #endif
 		return 0;
 	}
diff --git a/t/t5300-pack-object.sh b/t/t5300-pack-object.sh
index 1629fa80b0..0ec25c4966 100755
--- a/t/t5300-pack-object.sh
+++ b/t/t5300-pack-object.sh
@@ -445,8 +445,7 @@ test_expect_success !PTHREADS,C_LOCALE_OUTPUT 'pack-objects --threads=N or pack.
 	git -c pack.threads=2 pack-objects --stdout --all </dev/null >/dev/null 2>err &&
 	cat err &&
 	grep ^warning: err >warnings &&
-	test_line_count = 2 warnings &&
-	grep -F "no threads support, ignoring --threads" err &&
+	test_line_count = 1 warnings &&
 	grep -F "no threads support, ignoring pack.threads" err &&
 	git -c pack.threads=2 pack-objects --threads=4 --stdout --all </dev/null >/dev/null 2>err &&
 	grep ^warning: err >warnings &&

diff --git a/builtin/grep.c b/builtin/grep.c
index f4e08dd2b6..50e4bd2cd2 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -73,14 +73,14 @@ static pthread_mutex_t grep_mutex;
 
 static inline void grep_lock(void)
 {
-	if (num_threads)
-		pthread_mutex_lock(&grep_mutex);
+	assert(num_threads);
+	pthread_mutex_lock(&grep_mutex);
 }
 
 static inline void grep_unlock(void)
 {
-	if (num_threads)
-		pthread_mutex_unlock(&grep_mutex);
+	assert(num_threads);
+	pthread_mutex_unlock(&grep_mutex);
 }
 
 /* Signalled when a new work_item is added to todo. */