git diff --quiet -w: check and report the status

The option -w tells the diff machinery to inspect the contents to set the
exit status, instead of checking the blob object level difference alone.
However, --quiet tells the diff machinery not to look at the contents, which
means DIFF_FROM_CONTENTS has no chance to inspect the change.

Work it around by calling diff_flush_patch() with output sent to /dev/null.

Signed-off-by: Larry D'Anna <larry@elder-gods.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/diff.c b/diff.c
index 381cc8d4fd69ca31fb8fc8af31422160e3ec1fd3..7216b1e8db75fb28916be85139b816e9c6be93f8 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -3520,6 +3520,29 @@ void diff_flush(struct diff_options *options)
                separator++;
        }
 
+       if (output_format & DIFF_FORMAT_NO_OUTPUT &&
+           DIFF_OPT_TST(options, EXIT_WITH_STATUS) &&
+           DIFF_OPT_TST(options, DIFF_FROM_CONTENTS)) {
+               /*
+                * run diff_flush_patch for the exit status. setting
+                * options->file to /dev/null should be safe, becaue we
+                * aren't supposed to produce any output anyway.
+                */
+               if (options->close_file)
+                       fclose(options->file);
+               options->file = fopen("/dev/null", "w");
+               if (!options->file)
+                       die_errno("Could not open /dev/null");
+               options->close_file = 1;
+               for (i = 0; i < q->nr; i++) {
+                       struct diff_filepair *p = q->queue[i];
+                       if (check_pair_status(p))
+                               diff_flush_patch(p, options);
+                       if (options->found_changes)
+                               break;
+               }
+       }
+
        if (output_format & DIFF_FORMAT_PATCH) {
                if (separator) {
                        putc(options->line_termination, options->file);