https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61447
--- Comment #10 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
(In reply to Rich Felker from comment #9)
> As a related issue (let me know if I should open a new PR), the following
> code:
>
> struct foo {
> char c;
> alignas(long long) long long ll;
> };
>
> is producing a wrong/nonsensical error with gcc 4.9:
>
> error: '_Alignas' specifiers cannot reduce alignment of 'll'
>
> Apparently (again) GCC wrongly internally thinks the alignment of long long
> is 8, rather than 4. With earlier gcc versions it simply gives the wrong
> alignment (8 rather than 4).
This should be already fixed: PR61053 (earlier this month I backported the fix
even to 4.9).
