http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60761
--- Comment #1 from Martin Jambor <jamborm at gcc dot gnu.org> ---
This is because in dump_decl in gcc/cp/error.c there is:
case FUNCTION_DECL:
if (! DECL_LANG_SPECIFIC (t))
pp_string (pp, M_("<built-in>"));
and the revision causing this clears DECL_LANG_SPECIFIC.
