pytorch

84a31fb4 - Revert D18927221: Boxing uses if_constexpr instead of SFINAE

Revert D18927221: Boxing uses if_constexpr instead of SFINAE Test Plan: revert-hammer Differential Revision: D18927221 Original commit changeset: 70d99025b45e fbshipit-source-id: a4b650bbb6d76dda6086d88eb554f3c3077b0f76