https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67650
--- Comment #18 from Vincent <vincent.lextrait at gmail dot com> --- Still in 8.1, now with a different diagnosis: g++-8 -c -O3 67650.cpp 67650.cpp:33:8: warning: 'void AN<OC, RC>::rp() [with OC = LR<I, IE, (& ET)>::LLC; RC = BLKC]' used but never defined void rp(){} ^~ Ironically the message complains about the non definition of the member function, and displays that very definition...