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std::uses_allocator_construction_args

From cppreference.com
< cpp‎ | memory
 
C++
 
Memory management library
(exposition only*)
Allocators
(C++11)
(C++11)
uses_allocator_construction_args
(C++20)
(C++20)
(C++20)
Uninitialized memory algorithms
Constrained uninitialized memory algorithms
Memory resources
Uninitialized storage (until C++20)
(until C++20*)
(until C++20*)
(until C++20*)

Garbage collector support (until C++23)
(C++11)(until C++23)
(C++11)(until C++23)
(C++11)(until C++23)
(C++11)(until C++23)
(C++11)(until C++23)
(C++11)(until C++23)
 
Defined in header <memory>
T is not a specialization of std::pair
template< class T, class Alloc, class... Args >

constexpr auto uses_allocator_construction_args( const Alloc& alloc,

    Args&&... args ) noexcept;
 (1) (since C++20)
T is a specialization of std::pair
template< class T, class Alloc, class Tuple1, class Tuple2 >

constexpr auto uses_allocator_construction_args( const Alloc& alloc,

    std::piecewise_construct_t, Tuple1&& x, Tuple2&& y ) noexcept;
 (2) (since C++20)
template< class T, class Alloc >
constexpr auto uses_allocator_construction_args( const Alloc& alloc ) noexcept;
 (3) (since C++20)
template< class T, class Alloc, class U, class V >

constexpr auto uses_allocator_construction_args( const Alloc& alloc,

    U&& u, V&& v ) noexcept;
 (4) (since C++20)
template< class T, class Alloc, class U, class V >

constexpr auto uses_allocator_construction_args( const Alloc& alloc,

    std::pair<U, V>& pr ) noexcept;
 (5) (since C++23)
template< class T, class Alloc, class U, class V >

constexpr auto uses_allocator_construction_args( const Alloc& alloc,

    const std::pair<U, V>& pr ) noexcept;
 (6) (since C++20)
template< class T, class Alloc, class U, class V >

constexpr auto uses_allocator_construction_args( const Alloc& alloc,

    std::pair<U, V>&& pr ) noexcept;
 (7) (since C++20)
template< class T, class Alloc, class U, class V >

constexpr auto uses_allocator_construction_args( const Alloc& alloc,

    const std::pair<U, V>&& pr ) noexcept;
 (8) (since C++23)
template< class T, class Alloc, class NonPair >

constexpr auto uses_allocator_construction_args( const Alloc& alloc,

    NonPair&& non_pair ) noexcept;
 (9) (since C++20)

Prepares the argument list needed to create an object of the given type T by means of uses-allocator construction.

1) This overload participates in overload resolution only if T is not a specialization of std::pair. Returns std::tuple determined as follows:
2) This overload participates in overload resolution only if T is a specialization of std::pair. For T that is std::pair<T1, T2>, equivalent to 
return std::make_tuple(std::piecewise_construct,
    std::apply([&alloc](auto&&... args1)
        {
            return std::uses_allocator_construction_args<T1>(alloc,
                       std::forward<decltype(args1)>(args1)...);
        }, std::forward<Tuple1>(x)
    ),
    std::apply([&alloc](auto&&... args2)
        {
            return std::uses_allocator_construction_args<T2>(alloc,
                       std::forward<decltype(args2)>(args2)...);
        }, std::forward<Tuple2>(y)
    )
);
3) This overload participates in overload resolution only if T is a specialization of std::pair. Equivalent to 
return std::uses_allocator_construction_args<T>(alloc,
    std::piecewise_construct, std::tuple<>{}, std::tuple<>{}
);
4) This overload participates in overload resolution only if T is a specialization of std::pair. Equivalent to 
return std::uses_allocator_construction_args<T>(alloc,
    std::piecewise_construct,