[allocator.traits.general]

The class template allocator_traits supplies a uniform interface to all allocator types.

An allocator cannot be a non-class type, however, even if allocator_traits supplies the entire required interface.

[Note 1:

Thus, it is always possible to create a derived class from an allocator.

— end note]

If a program declares an explicit or partial specialization of allocator_traits, the program is ill-formed, no diagnostic required.

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namespace std { template<class Alloc> struct allocator_traits { using allocator_type = Alloc; using value_type = Alloc::value_type; using pointer = see below; using const_pointer = see below; using void_pointer = see below; using const_void_pointer = see below; using difference_type = see below; using size_type = see below; using propagate_on_container_copy_assignment = see below; using propagate_on_container_move_assignment = see below; using propagate_on_container_swap = see below; using is_always_equal = see below; template<class T> using rebind_alloc = see below; template<class T> using rebind_traits = allocator_traits<rebind_alloc<T>>; static constexpr pointer allocate(Alloc& a, size_type n); static constexpr pointer allocate(Alloc& a, size_type n, const_void_pointer hint); static constexpr allocation_result<pointer, size_type> allocate_at_least(Alloc& a, size_type n); static constexpr void deallocate(Alloc& a, pointer p, size_type n); template<class T, class. Args> static constexpr void construct(Alloc& a, T* p, Args&&. args); template<class T> static constexpr void destroy(Alloc& a, T* p); static constexpr size_type max_size(const Alloc& a) noexcept; static constexpr Alloc select_on_container_copy_construction(const Alloc& rhs); }; }