#include <algorithm>#include <cassert>#include <cstddef>#include <new>#include <string_view>#include <type_traits>#include <utility> // Constructs a T at the uninitialized memory pointed to by p using// list-initialization for aggregates and non-list initialization otherwise.template<class T,class...Args>T* construct(T* p, Args&&...args){ifconstexpr(std::is_aggregate_v<T>)return::new(static_cast<void*>(p)) T{std::forward<Args>(args)...};elsereturn::new(static_cast<void*>(p)) T(std::forward<Args>(args)...);} struct A{int x, y;};static_assert(std::is_aggregate_v<A>); struct B{int i;std::string_view str;     B(int i,std::string_view str): i(i), str(str){}};static_assert(not std::is_aggregate_v<B>); template<typename...Ts>using aligned_storage_t= alignas(Ts...)std::byte[std::max({sizeof(Ts)...})]; int main(){    aligned_storage_t<A, B> storage;     A& a=*construct(reinterpret_cast<A*>(&storage),1,2);assert(a.x==1 and a.y==2);     B& b=*construct(reinterpret_cast<B*>(&storage),3,"4");assert(b.i==3 and b.str=="4");}