On 7/31/23 21:46, Артём Колпаков via Std-Discussion wrote:

> alignas(T) std::byte storage_[sizeof(T)];
> T *ptr_ = ::new (&storage_) T;

Even better: std::construct_at

> *use* reinterpret_cast<T *>(&storage_)
>
> I can't figure out if the second application is valid in general, or is
> it UB? It seems that the standard of the language through prescriptions

Undefined behaviour. See https://wg21.link/p2590