gistfile1.cpp

// Compile with clang++ -std=c++14

#include <functional>

struct foo {
    // Implicitly compiler-generated default destructor
    // ~foo() { }
};

template<typename T>
void make_t(const std::function<auto (T&) -> void> f)
{
    // Allocate space for T
    alignas(T) char c[sizeof(T)];
    T* t = reinterpret_cast<T*>(c);
    
    // Placement new
    new (c) T();
    
    // Use T, assuming no exception
    f(*t);
    
    // Destruct T
    t->~T();
}

int main()
{
    make_t<foo>([](auto){});

    return 0;
}