diff --color-moved: rewind when discarding pmb

Signed-off-by: Junio C Hamano <[email protected]>

Author: phillipwood

diff.c

@@ -1205,7 +1205,15 @@ static void mark_color_as_moved(struct diff_options *o,
 		if (!match) {
 			int i;
 
-			adjust_last_block(o, n, block_length);
+			if (!adjust_last_block(o, n, block_length) &&
+			    block_length > 1) {
+				/*
+				 * Rewind in case there is another match
+				 * starting at the second line of the block
+				 */
+				match = NULL;
+				n -= block_length;
+			}
 			for(i = 0; i < pmb_nr; i++)
 				moved_block_clear(&pmb[i]);
 			pmb_nr = 0;
@@ -1230,10 +1238,20 @@ static void mark_color_as_moved(struct diff_options *o,
 		pmb_nr = shrink_potential_moved_blocks(pmb, pmb_nr);
 
 		if (pmb_nr == 0) {
-			fill_potential_moved_blocks(
-				o, hm, match, l, &pmb, &pmb_alloc, &pmb_nr);
-			if (adjust_last_block(o, n, block_length) &&
-			    pmb_nr && last_symbol != l->s)
+			int contiguous = adjust_last_block(o, n, block_length);
+
+			if (!contiguous && block_length > 1)
+				/*
+				 * Rewind in case there is another match
+				 * starting at the second line of the block
+				 */
+				n -= block_length;
+			else
+				fill_potential_moved_blocks(o, hm, match, l,
+							    &pmb, &pmb_alloc,
+							    &pmb_nr);
+
+			if (contiguous && pmb_nr && last_symbol != l->s)
 				flipped_block = (flipped_block + 1) % 2;
 			else
 				flipped_block = 0;

t/t4015-diff-whitespace.sh

@@ -1833,6 +1833,52 @@ test_expect_success '--color-moved treats adjacent blocks as separate for MIN_AL
 	test_cmp expected actual
 '
 
+test_expect_success '--color-moved rewinds for MIN_ALNUM_COUNT' '
+	git reset --hard &&
+	test_write_lines >file \
+		A B C one two three four five six seven D E F G H I J &&
+	git add file &&
+	test_write_lines >file \
+		one two A B C D E F G H I J two three four five six seven &&
+	git diff --color-moved=zebra -- file &&
+
+	git diff --color-moved=zebra --color -- file >actual.raw &&
+	grep -v "index" actual.raw | test_decode_color >actual &&
+	cat >expected <<-\EOF &&
+	<BOLD>diff --git a/file b/file<RESET>
+	<BOLD>--- a/file<RESET>
+	<BOLD>+++ b/file<RESET>
+	<CYAN>@@ -1,13 +1,8 @@<RESET>
+	<GREEN>+<RESET><GREEN>one<RESET>
+	<GREEN>+<RESET><GREEN>two<RESET>
+	 A<RESET>
+	 B<RESET>
+	 C<RESET>
+	<RED>-one<RESET>
+	<BOLD;MAGENTA>-two<RESET>
+	<BOLD;MAGENTA>-three<RESET>
+	<BOLD;MAGENTA>-four<RESET>
+	<BOLD;MAGENTA>-five<RESET>
+	<BOLD;MAGENTA>-six<RESET>
+	<BOLD;MAGENTA>-seven<RESET>
+	 D<RESET>
+	 E<RESET>
+	 F<RESET>
+	<CYAN>@@ -15,3 +10,9 @@<RESET> <RESET>G<RESET>
+	 H<RESET>
+	 I<RESET>
+	 J<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>two<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>three<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>four<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>five<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>six<RESET>
+	<BOLD;CYAN>+<RESET><BOLD;CYAN>seven<RESET>
+	EOF
+
+	test_cmp expected actual
+'
+
 test_expect_success 'move detection with submodules' '
 	test_create_repo bananas &&
 	echo ripe >bananas/recipe &&