tasklist-id.patch

diff --git a/extensions/tasklist.c b/extensions/tasklist.c
index 7bef454..edcf754 100644
--- a/extensions/tasklist.c
+++ b/extensions/tasklist.c
@@ -120,6 +120,14 @@ static void html_render(cmark_syntax_extension *extension,
     cmark_html_render_cr(renderer->html);
     cmark_strbuf_puts(renderer->html, "<li");
     cmark_html_render_sourcepos(node, renderer->html, options);
+    // Insert a unique identifier.
+#define TASKLIST_ID_SIZE 100
+    char buffer[TASKLIST_ID_SIZE];
+    snprintf(buffer, TASKLIST_ID_SIZE, " data-gfm-task=\"%d:%d-%d:%d\"",
+             cmark_node_get_start_line(node), cmark_node_get_start_column(node),
+             cmark_node_get_end_line(node), cmark_node_get_end_column(node));
+#undef TASKLIST_ID_SIZE
+    cmark_strbuf_puts(renderer->html, buffer);
     cmark_strbuf_putc(renderer->html, '>');
     if (node->as.list.checked) {
       cmark_strbuf_puts(renderer->html, "<input type=\"checkbox\" checked=\"\" disabled=\"\" /> ");