[mattnewport]

Backwards compatibility in C++ means "your existing code still compiles and does the same thing". Can you give an example of a situation where that could be achieved with your proposal?

[wtetzner]

Well, my thought was that you'd just have different profiles, like is already used:

    -std=c++20-full

or

    -std=c++20-light

Perhaps c++20-light could never become the default, since it would break backwards compatibility, but you could always set the flag.

I dunno. It was just a thought I had when reading about the new feature, not something I've thought through.