rev-list: make --count work with --objects

The current behavior from "rev-list --count --objects" is nonsensical:
we enumerate all of the objects except commits, but then give a count of
commits. This wasn't planned, and is just what the code happens to do.

Instead, let's give the answer the user almost certainly wanted: the
full count of objects.

Note that there are more complicated cases around cherry-marking, etc.
We'll punt on those for now, but let the user know that we can't produce
an answer (rather than giving them something useless).

We'll test both the new feature as well as a vanilla --count of commits,
since that surprisingly doesn't seem to be covered in the existing
tests.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/rev-list.c

@@ -253,11 +253,19 @@ static int finish_object(struct object *obj, const char *name, void *cb_data)
 static void show_object(struct object *obj, const char *name, void *cb_data)
 {
 	struct rev_list_info *info = cb_data;
+	struct rev_info *revs = info->revs;
+
 	if (finish_object(obj, name, cb_data))
 		return;
 	display_progress(progress, ++progress_counter);
 	if (info->flags & REV_LIST_QUIET)
 		return;
+
+	if (revs->count) {
+		revs->count_right++;
+		return;
+	}
+
 	if (arg_show_object_names)
 		show_object_with_name(stdout, obj, name);
 	else
@@ -584,6 +592,11 @@ int cmd_rev_list(int argc, const char **argv, const char *prefix)
 	if (revs.show_notes)
 		die(_("rev-list does not support display of notes"));
 
+	if (revs.count &&
+	    (revs.tag_objects || revs.tree_objects || revs.blob_objects) &&
+	    (revs.left_right || revs.cherry_mark))
+		die(_("marked counting is incompatible with --objects"));
+
 	if (filter_options.choice)
 		use_bitmap_index = 0;
 

t/t6000-rev-list-misc.sh

@@ -148,4 +148,16 @@ test_expect_success 'rev-list --end-of-options' '
 	test_cmp expect actual
 '
 
+test_expect_success 'rev-list --count' '
+	count=$(git rev-list --count HEAD) &&
+	git rev-list HEAD >actual &&
+	test_line_count = $count actual
+'
+
+test_expect_success 'rev-list --count --objects' '
+	count=$(git rev-list --count --objects HEAD) &&
+	git rev-list --objects HEAD >actual &&
+	test_line_count = $count actual
+'
+
 test_done