diff.c: --ws-check-deleted optionjc/diff-ws-check-deleted

Traditionally, we only cared about whitespace breakages introduced
in new lines.  Some people want to paint whitespace breakages on old
lines, too.  When they see a whitespace breakage on a new line, they
can spot the same kind of whitespace breakage on the corresponding
old line and want to say "Ah, those breakages are there but they
were inherited from the original, so let's not touch them for now."

Enable such use case with the new option, "--ws-check-deleted".

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 20 insertions, 1 deletions

diff --git a/diff.c b/diff.c
index 75b134291a..30eeaea06a 100644
--- a/diff.c
+++ b/diff.c
@@ -503,8 +503,22 @@ static void emit_del_line(const char *reset,
 			  const char *line, int len)
 {
 	const char *set = diff_get_color(ecbdata->color_diff, DIFF_FILE_OLD);
+	const char *ws = NULL;
 
-	emit_line_0(ecbdata->opt, set, reset, '-', line, len);
+	if (ecbdata->opt->ws_check_deleted) {
+		ws = diff_get_color(ecbdata->color_diff, DIFF_WHITESPACE);
+		if (!*ws)
+			ws = NULL;
+	}
+
+	if (!ws)
+		emit_line_0(ecbdata->opt, set, reset, '-', line, len);
+	else {
+		/* Emit just the prefix, then the rest. */
+		emit_line_0(ecbdata->opt, set, reset, '-', "", 0);
+		ws_check_emit(line, len, ecbdata->ws_rule,
+			      ecbdata->opt->file, set, reset, ws);
+	}
 }
 
 static void emit_hunk_header(struct emit_callback *ecbdata,
@@ -3823,6 +3837,11 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 	else if (skip_prefix(arg, "--submodule=", &arg))
 		return parse_submodule_opt(options, arg);
 
+	else if (!strcmp(arg, "--ws-check-deleted"))
+		options->ws_check_deleted = 1;
+	else if (!strcmp(arg, "--no-ws-check-deleted"))
+		options->ws_check_deleted = 0;
+
 	/* misc options */
 	else if (!strcmp(arg, "-z"))
 		options->line_termination = 0;