diff: accept -- when using --no-index

Accept -- as an "end of options" marker even when using --no-index.
Previously, the -- triggered a "normal" index/tree diff and subsequently
failed because of the unrecognized (in that mode) --no-index.

Note that the second loop can treat '--' as a normal option, because
the preceding checks ensure it is the third-to-last argument.

While at it, fix the parsing of "-q" option in --no-index mode as well.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff-no-index.c

@@ -173,8 +173,10 @@ void diff_no_index(struct rev_info *revs,
 
 	/* Were we asked to do --no-index explicitly? */
 	for (i = 1; i < argc; i++) {
-		if (!strcmp(argv[i], "--"))
-			return;
+		if (!strcmp(argv[i], "--")) {
+			i++;
+			break;
+		}
 		if (!strcmp(argv[i], "--no-index"))
 			no_index = 1;
 		if (argv[i][0] != '-')
@@ -212,8 +214,10 @@ void diff_no_index(struct rev_info *revs,
 		int j;
 		if (!strcmp(argv[i], "--no-index"))
 			i++;
-		else if (!strcmp(argv[1], "-q"))
+		else if (!strcmp(argv[i], "-q"))
 			options |= DIFF_SILENT_ON_REMOVED;
+		else if (!strcmp(argv[i], "--"))
+			i++;
 		else {
 			j = diff_opt_parse(&revs->diffopt, argv + i, argc - i);
 			if (!j)

t/t4013-diff-various.sh

@@ -261,6 +261,7 @@ diff --patch-with-stat -r initial..side
 diff --patch-with-raw -r initial..side
 diff --name-status dir2 dir
 diff --no-index --name-status dir2 dir
+diff --no-index --name-status -- dir2 dir
 diff master master^ side
 EOF
 

t/t4013/diff.diff_--no-index_--name-status_--_dir2_dir

@@ -0,0 +1,3 @@
+$ git diff --no-index --name-status -- dir2 dir
+A	dir/sub
+$