std::ranges::destroy(3)

NAME
std::ranges::destroy - std::ranges::destroy

Synopsis
   Defined in header <memory>
   Call signature
   template< no-throw-input-iterator I, no-throw-sentinel-for<I> S >
       requires std::destructible<std::iter_value_t<I>> (1) (since C++20)
   constexpr I destroy( I first, S last ) noexcept;
   template< no-throw-input-range R >
       requires std::destructible<ranges::range_value_t<R>> (2) (since C++20)
   constexpr ranges::borrowed_iterator_t<R> destroy( R&& r )
   noexcept;
   1) Destroys the objects in the range [first, last), as if by
 for (; first != last; ++first)
     std::ranges::destroy_at(std::addressof(*first));
 return first;
   2) Same as (1), but uses r as the source range, as if using ranges::begin(r) as
   first and ranges::end(r) as last.
   The function-like entities described on this page are niebloids, that is:
     * Explicit template argument lists cannot be specified when calling any of them.
     * None of them are visible to argument-dependent lookup.
     * When any of them are found by normal unqualified lookup as the name to the left
       of the function-call operator, argument-dependent lookup is inhibited.
   In practice, they may be implemented as function objects, or with special compiler
   extensions.

Parameters
   first, last - iterator-sentinel pair denoting the range of elements to destroy
   r - the range to destroy

Return value
   An iterator compares equal to last.

Complexity
   Linear in the distance between first and last.

Possible implementation
   struct destroy_fn
   {
       template<no-throw-input-iterator I, no-throw-sentinel-for<I> S>
           requires std::destructible<std::iter_value_t<I>>
       constexpr I operator()(I first, S last) const noexcept
       {
           for (; first != last; ++first)
               std::ranges::destroy_at(std::addressof(*first));
           return first;
       }
       template<no-throw-input-range R>
           requires std::destructible<std::ranges::range_value_t<R>>
       constexpr std::ranges::borrowed_iterator_t<R> operator()(R&& r) const noexcept
       {
           return operator()(std::ranges::begin(r), std::ranges::end(r));
       }
   };
   inline constexpr destroy_fn destroy{};

Example
   The following example demonstrates how to use ranges::destroy to destroy a
   contiguous sequence of elements. // Run this code
 #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));
     std::ranges::destroy(ptr, ptr + 8);
 }

Output:
 0 destructed
 1 destructed
 2 destructed
 3 destructed
 4 destructed
 5 destructed
 6 destructed
 7 destructed

See also
   ranges::destroy_n destroys a number of objects in a range
   (C++20) (niebloid)
   ranges::destroy_at destroys an object at a given address
   (C++20) (niebloid)
   destroy destroys a range of objects
   (C++17) (function template)