https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89421
--- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> --- (In reply to Marek Polacek from comment #4) > Jason, should we also return NULL_TREE for lambdas inside template parameter > list (in retrieve_specialization)? That's not sufficient, even if it probably makes some sense. (This likely should be P2 instead of P1, as it's previously invalid code.)
