20 Memory management library [mem]

20.3 Pointer tagging [ptrtag]

20.3.2 Class template pointer_tag_pair [ptrtag.pair]

20.3.2.3 Support for overaligned pointers [ptrtag.pair.overalign]

template<size_t PromisedAlignment,
         tagging-compatible-pointee<pointer_type, bits_requested, PromisedAlignment> U>
  static constexpr pointer_tag_pair from_overaligned(U* p, tag_type t);

Constant When: Preconditions are met.

Preconditions:

(2.1)
p is not a pointer past the end of an object ([basic.compound]).
(2.2)
p == nullptr || is_sufficiently_aligned<PromisedAlignment>(p) is true.
(2.3)
tag-bit-width(t) <= bits_requested is true.

Returns: An object ptp of type pointer_tag_pair such that both ptp.pointer() is equal to p and ptp.tag() is equal to t.

Throws: Nothing.