https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102377
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The reason we don't see it in every test is that this one uses:
// { dg-options "-Wsystem-headers -Wnarrowing" }
But I think the warning is pointing out a real issue. Since the interference
sizes vary with -mtune options, we shouldn't use them in <atomic>, since that's
defining a public ABI (or will be, once our C++20 support is non-experimental).
