Merge branch 'jk/diff-highlight-identical-pairs'

gitster · gitster · commit ebd8fa7e1291 · 2026-03-27T11:00:00.000-07:00
The handling of the incomplete lines at the end by "git
diff-highlight" has been fixed.

* jk/diff-highlight-identical-pairs:
  contrib/diff-highlight: do not highlight identical pairs
diff --git a/contrib/diff-highlight/DiffHighlight.pm b/contrib/diff-highlight/DiffHighlight.pm
@@ -273,6 +273,18 @@ sub highlight_line {
 # or suffix (disregarding boring bits like whitespace and colorization).
 sub is_pair_interesting {
 	my ($a, $pa, $sa, $b, $pb, $sb) = @_;
+
+	# We hit this case if the prefix consumed the entire line, meaning
+	# that two lines are identical. This generally shouldn't happen,
+	# since it implies the diff isn't minimal (you could shrink the hunk by
+	# making this a context line). But you can see it when the line
+	# content is the same, but the trailing newline is dropped, like:
+	#
+	#   -foo
+	#   +foo
+	#   \No newline at end of file
+	return 0 if $pa == @$a || $pb == @$b;
+
 	my $prefix_a = join('', @$a[0..($pa-1)]);
 	my $prefix_b = join('', @$b[0..($pb-1)]);
 	my $suffix_a = join('', @$a[($sa+1)..$#$a]);
diff --git a/contrib/diff-highlight/t/t9400-diff-highlight.sh b/contrib/diff-highlight/t/t9400-diff-highlight.sh
@@ -340,4 +340,15 @@ test_expect_success 'diff-highlight handles --graph with leading dash' '
 	test_cmp expect actual
 '
 
+test_expect_success 'highlight diff that removes final newline' '
+	printf "content\n" >a &&
+	printf "content" >b &&
+	dh_test a b <<-\EOF
+	@@ -1 +1 @@
+	-content
+	+content
+	\ No newline at end of file
+	EOF
+'
+
 test_done
