[Bug c++/95609] span could have better layout

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95609

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Niall Douglas from comment #0)
> I would assume that the ABI ship has sailed, as usual

Nope.