commit-graph: when incompatible with graphs, indicate why

dscho · gitster · commit c85eec7fc37e · 2021-02-11T09:33:01.000-08:00
When `gc.writeCommitGraph = true`, it is possible that the commit-graph
is _still_ not written: replace objects, grafts and shallow repositories
are incompatible with the commit-graph feature.

Under such circumstances, we need to indicate to the user why the
commit-graph was not written instead of staying silent about it.

Signed-off-by: Johannes Schindelin &lt;johannes.schindelin@gmx.de&gt;
Acked-by: Derrick Stolee &lt;dstolee@microsoft.com&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
diff --git a/commit-graph.c b/commit-graph.c
@@ -205,16 +205,24 @@ static int commit_graph_compatible(struct repository *r)
 
 	if (read_replace_refs) {
 		prepare_replace_object(r);
-		if (hashmap_get_size(&r->objects->replace_map->map))
+		if (hashmap_get_size(&r->objects->replace_map->map)) {
+			warning(_("repository contains replace objects; "
+			       "skipping commit-graph"));
 			return 0;
+		}
 	}
 
 	prepare_commit_graft(r);
 	if (r->parsed_objects &&
-	    (r->parsed_objects->grafts_nr || r->parsed_objects->substituted_parent))
+	    (r->parsed_objects->grafts_nr || r->parsed_objects->substituted_parent)) {
+		warning(_("repository contains (deprecated) grafts; "
+		       "skipping commit-graph"));
 		return 0;
-	if (is_repository_shallow(r))
+	}
+	if (is_repository_shallow(r)) {
+		warning(_("repository is shallow; skipping commit-graph"));
 		return 0;
+	}
 
 	return 1;
 }
