https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97943
--- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> --- (In reply to Jason Merrill from comment #6) > I think we should reject trying to clear the padding of a > flexible/zero-length array, with error rather than sorry. And handle an > array at the end of a struct like any other array. Nobody should be using > this builtin with the struct hack, it's impossible for it to do anything > sensible. I agree. In the unlikely scenario somebody comes up with a good use, we can relax it later. If we allow it now somebody will find a way to depend on it "working" and then it's harder to remove later.