#include <cassert>
#include <cstring>
#include <new>

int main()
{
    alignas(int) unsigned char buff1[sizeof(int)];
    alignas(int) unsigned char buff2[sizeof(int)];

    new (buff1) int {42};
    std::memcpy(buff2, buff1, sizeof(buff1));

    assert(*std::launder(reinterpret_cast<int*>(buff2)) == 42); // is it ok?
}