Hi Everyone, Over the weekend I added changes to Boost.Optional in develop which caused regression in Boost.Beast and maybe more libraries. I would like to ask for your input as to how to best approach this. The change was: for trivial `T` use a different specialization of `optional<T>` which is trivially-copyable. For this, I need the ability to declare defaulted functions, and to detect that a given type is trivial. Boost.TypeTraits do not have `is_trivial` trait, so I compose it form `has_trivial_move` and the like. But it seems there are compilers for which Boost.config and Boost.TypeTraits report support for deleted functions/triviality detection, but where this support is buggy. The following is a test case in type_traits by Vinnie Falco: https://github.com/boostorg/type_traits/pull/52/commits/9779157a787620d16330... In addition, the deadline for changes in release 1.66 is getting nigh. I can see a couple of ways to fix this: 1. Fix Boost.Config and/or Boost.TypeTraits so that they only report support for the features in question when it is supported without bugs. But I do not know if there is enough time for this given the deadline. 2. Disable my feature on the compilers with buggy support. But I would need a help from someone who knows all the compilers and their bugs in implementation of trivial type traits so that I can put the wight `#ifdef`s. 3. Just revert my changes to Optional, which is also an option, but would also be a loss. Any input from Boost experts would be appreciated. Regards, &rzej;