BUILTIN_MARKER
pbstr(BUILTIN_MARKER);
if (strncmp(defn, BUILTIN_MARKER, sizeof(BUILTIN_MARKER) - 1) == 0 &&
(p = macro_getbuiltin(defn + sizeof(BUILTIN_MARKER) - 1)) != NULL) {
d->defn = xstrdup(defn + sizeof(BUILTIN_MARKER) - 1);