std::destroy_at

Since C++20

Header: <memory>

If T is not an array type, calls the destructor of the object pointed to by p, as if by p->~T().

# Declarations

template< class T >
void destroy_at( T* p );

(since C++17) (until C++20)

template< class T >
constexpr void destroy_at( T* p );

(since C++20)

# Parameters

# Return value

(none)

# Notes

destroy_at deduces the type of object to be destroyed and hence avoids writing it explicitly in the destructor call.

When destroy_at is called in the evaluation of some constant expression e, the argument p must point to an object whose lifetime began within the evaluation of e.

# Example

#include <iostream>
#include <memory>
#include <new>
 
struct Tracer
{
    int value;
    ~Tracer() { std::cout << value << " destructed\n"; }
};
 
int main()
{
    alignas(Tracer) unsigned char buffer[sizeof(Tracer) * 8];
 
    for (int i = 0; i < 8; ++i)
        new(buffer + sizeof(Tracer) * i) Tracer{i}; //manually construct objects
 
    auto ptr = std::launder(reinterpret_cast<Tracer*>(buffer));
 
    for (int i = 0; i < 8; ++i)
        std::destroy_at(ptr + i);
}

# See also