> I don't really care if it isn't portable.

You don't care because your job is not to ensure that a new release of C++ doesn't break production code. You gaze at your navel and pretend that's the universe everyone is bound to. But there are others using C++, and using it in production software. Some of them care, and your subjective opinions don't have an impact in everyone else's requirements.

> I only have to work with Clang, personally.

Read Clang's manual and check what compiler flags you need to flip to get that behavior. It's already there.