[Bug libstdc++/87544] alloc-size-larger-than incorrectly triggered

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87544

--- Comment #22 from Jonathan Wakely <redi at gcc dot gnu.org> ---
N.B. in case somebody does want to backport it, the fix for this depends on the
fix for PR 78448.