https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84541
--- Comment #2 from Volker Reichelt <reichelt at gcc dot gnu.org> --- Paolo, you're right. Sorry for the noise. The "-fconcept" parameter is a left-over from the larger testcase where this snippet was derived from. The ICE can be reproduced with GCC 4.9.0 and only needs "-std=c++14" or "-std=c++1y" to be triggered.
