https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100124
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- I will let someone comment on the flexible array extension. But I will note GCC treats (all) arrays at the end of a POD struct as a flexible one so the question I have is more about the ubsan issue you are running into, is that with GCC or with clang/LLVM?
