< cpp‎ | memory
Defined in header <memory>
constexpr std::allocator_arg_t allocator_arg = std::allocator_arg_t();
(since C++11)

std::allocator_arg is a constant of type std::allocator_arg_t used to disambiguate, at call site, the overloads of the constructors and member functions of allocator-aware objects, such as std::tuple, std::function, std::promise, and std::packaged_task.

[edit] See also

tag type used to select allocator-aware constructor overloads
checks if the specified type supports uses-allocator construction
(class template)