https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100992
--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> --- The first static_assert that only fails for 11.4 was probably caused by r11-9927-gd65b274f1f44c5 in 11.4 which removed the workaround for Bug 96592 Maybe we shouldn't have removed the workaround for GCC 11, only for the later releases. The second static_assert fails for all releases though.
