[PATCH 23/26] diff.c: color moved lines differently, plain mode

[Stefan Beller <sbeller@google.com>]

Add the 'plain' mode for move detection of code.
This omits the checking for adjacent blocks, so it is not as useful.
If you have a lot of the same blocks moved in the same patch, the 'Zebra'
would end up slow as it is O(n^2) (n is number of same blocks).
So this may be useful there and is generally easy to add

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 diff.c                     |  5 +++++
 diff.h                     |  1 +
 t/t4015-diff-whitespace.sh | 51 +++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 56 insertions(+), 1 deletion(-)

diff --git a/diff.c b/diff.c
index 20c1f9b99f..0d41a53b76 100644
--- a/diff.c
+++ b/diff.c
@@ -246,6 +246,8 @@ static int parse_color_moved(const char *arg)
 {
 	if (!strcmp(arg, "no"))
 		return COLOR_MOVED_NO;
+	else if (!strcmp(arg, "plain"))
+		return COLOR_MOVED_PLAIN;
 	else if (!strcmp(arg, "zebra"))
 		return COLOR_MOVED_ZEBRA;
 	else
@@ -830,6 +832,9 @@ static void mark_color_as_moved(struct diff_options *o,
 
 		l->flags |= DIFF_SYMBOL_MOVED_LINE;
 
+		if (o->color_moved == COLOR_MOVED_PLAIN)
+			continue;
+
 		/* Check any potential block runs, advance each or nullify */
 		for (i = 0; i < pmb_nr; i++) {
 			struct moved_entry *p = pmb[i];
diff --git a/diff.h b/diff.h
index 7726ad255c..1aae8738ca 100644
--- a/diff.h
+++ b/diff.h
@@ -190,6 +190,7 @@ struct diff_options {
 	struct emitted_diff_symbols *emitted_symbols;
 	enum {
 		COLOR_MOVED_NO = 0,
+		COLOR_MOVED_PLAIN = 1,
 		COLOR_MOVED_ZEBRA = 2,
 	} color_moved;
 };
diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index 4a03766f1f..1ca16435d6 100755
--- a/t/t4015-diff-whitespace.sh
+++ b/t/t4015-diff-whitespace.sh
@@ -986,7 +986,7 @@ test_expect_success 'detect moved code, complete file' '
 	git mv test.c main.c &&
 	test_config color.diff.oldMoved "normal red" &&
 	test_config color.diff.newMoved "normal green" &&
-	git diff HEAD --color-moved --no-renames | test_decode_color >actual &&
+	git diff HEAD --color-moved=zebra --no-renames | test_decode_color >actual &&
 	cat >expected <<-\EOF &&
 	<BOLD>diff --git a/main.c b/main.c<RESET>
 	<BOLD>new file mode 100644<RESET>
@@ -1130,6 +1130,55 @@ test_expect_success 'detect malicious moved code, inside file' '
 	test_cmp expected actual
 '
 
+test_expect_success 'plain moved code, inside file' '
+	test_config color.diff.oldMoved "normal red" &&
+	test_config color.diff.newMoved "normal green" &&
+	test_config color.diff.oldMovedAlternative "blue" &&
+	test_config color.diff.newMovedAlternative "yellow" &&
+	# needs previous test as setup
+	git diff HEAD --no-renames --color-moved=plain| test_decode_color >actual &&
+	cat <<-\EOF >expected &&
+	<BOLD>diff --git a/main.c b/main.c<RESET>
+	<BOLD>index 27a619c..7cf9336 100644<RESET>
+	<BOLD>--- a/main.c<RESET>
+	<BOLD>+++ b/main.c<RESET>
+	<CYAN>@@ -5,13 +5,6 @@<RESET> <RESET>printf("Hello ");<RESET>
+	 printf("World\n");<RESET>
+	 }<RESET>
+	 <RESET>
+	<BRED>-int secure_foo(struct user *u)<RESET>
+	<BRED>-{<RESET>
+	<BRED>-if (!u->is_allowed_foo)<RESET>
+	<BRED>-return;<RESET>
+	<BRED>-foo(u);<RESET>
+	<BRED>-}<RESET>
+	<BRED>-<RESET>
+	 int main()<RESET>
+	 {<RESET>
+	 foo();<RESET>
+	<BOLD>diff --git a/test.c b/test.c<RESET>
+	<BOLD>index 1dc1d85..2bedec9 100644<RESET>
+	<BOLD>--- a/test.c<RESET>
+	<BOLD>+++ b/test.c<RESET>
+	<CYAN>@@ -4,6 +4,13 @@<RESET> <RESET>int bar()<RESET>
+	 printf("Hello World, but different\n");<RESET>
+	 }<RESET>
+	 <RESET>
+	<BGREEN>+<RESET><BGREEN>int secure_foo(struct user *u)<RESET>
+	<BGREEN>+<RESET><BGREEN>{<RESET>
+	<BGREEN>+<RESET><BGREEN>foo(u);<RESET>
+	<BGREEN>+<RESET><BGREEN>if (!u->is_allowed_foo)<RESET>
+	<BGREEN>+<RESET><BGREEN>return;<RESET>
+	<BGREEN>+<RESET><BGREEN>}<RESET>
+	<BGREEN>+<RESET>
+	 int another_function()<RESET>
+	 {<RESET>
+	 bar();<RESET>
+	EOF
+
+	test_cmp expected actual
+'
+
 test_expect_success 'no effect from --color-moved with --word-diff' '
 	cat <<-\EOF >text.txt &&
 	Lorem Ipsum is simply dummy text of the printing and typesetting industry.
-- 
2.12.2.575.gb14f27f917