19 General utilities library [utilities]

19.5 Tuples [tuple]

19.5.3 Class template tuple [tuple.tuple] Tuple traits [tuple.traits]

template<class... Types, class Alloc> struct uses_allocator<tuple<Types...>, Alloc> : true_type { };
Requires: Alloc shall satisfy the Cpp17Allocator requirements (Table 33).
Specialization of this trait informs other library components that tuple can be constructed with an allocator, even though it does not have a nested allocator_­type.
end note