https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89304
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> --- With -ftemplate-depth=50 it fails in about 5 seconds. -ftemplate-depth=100 takes 18s -ftemplate-depth=200 takes 1m27s So there's something quadratic in the nested tuple instantiations which means that reaching the default template depth of 900 takes a silly length of time.
