+static struct strbuf *diff_output_prefix_callback(struct diff_options *opt, void *data)
+{
+ struct git_graph *graph = data;
+ static struct strbuf msgbuf = STRBUF_INIT;
+
+ assert(graph);
+
+ strbuf_reset(&msgbuf);
+ graph_padding_line(graph, &msgbuf);
+ return &msgbuf;
+}
+