https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84387
--- Comment #8 from Jerry DeLisle <jvdelisle at gcc dot gnu.org> --- We have confirmed this is addressed in the standard, though, as usual, one has to read two or three conditions and deduce it. 2018: Section 12.6.4.8.4. I am looking at how to fix.