Obtain an executor with the default allocator property.

basic_system_executor< Blocking, Relationship, std::allocator< void > > require(
    execution::allocator_t< void > ) const;

Do not call this function directly. It is intended for use with the require customisation point.

For example:

asio::system_executor ex1;
auto ex2 = asio::require(ex1,
    asio::execution::allocator);