https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89089
--- Comment #3 from Hannes Hauswedell <h2+bugs at fsfe dot org> --- Created attachment 45540 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=45540&action=edit second ICE g++9 -std=c++17 -fconcepts -Wall -Wextra concat.cpp
