https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69098
--- Comment #5 from Martin Sebor <msebor at gcc dot gnu.org> --- I looks like it was introduced in r186681. The last good commit before that is r186667, and none of those in between touch the C++ front end. Though the changes in r186681 look very mechanical and not related to templates at all so I'm not sure.
