[ 2020-05-10; Daniel comments and provides wording ]
The inconsistency between the two any::emplace overloads have been removed by resolving LWG 2754 to use Constraints: elements. The last Mandating paper (P1460R1), adopted in Prague, changed the Requires: elements for variant::emplace, "I < sizeof...(Types)" to Mandates:, but that paper was focused on fixing inappropriate preconditions, not searching for consistency here. Given that the in_place_index_t constructors of variant uses SFINAE-conditions for this form of static precondition violation, I recommend that its emplace functions use the same style, which would bring them also in consistency with their corresponding type-based emplace forms that are Mandates:-free but delegate to the index-based forms.