C++20 fixes
C++20 fixes

Summary: C++20 fixes

Reviewed By: ispeters, meyering

Differential Revision: D31832469

fbshipit-source-id: 367b9d68104ae8a6e58cc11445b0489cbe9bcf84

facebook/folly,facebook/folly,facebook/folly,facebook/folly,facebook/folly