[Bug libstdc++/86189] not equal allocators not behaving as expected

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86189

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Rian Quinn from comment #0)
>     template <typename U>
>     myallocator4(const myallocator4<U> &other) noexcept
>     { (void) other; }

You know you can just not name a parameter, instead of casting it to void?

     template <typename U>
     myallocator4(const myallocator4<U> &) noexcept
     { }