This particular compiler does require bootstrapping, and that's obviously what "the compiler" is referring to in that comment.
Building your compiler in another language doesn't help at all. In fact, it just makes it worse. Dogfooding C++20 in your compiler that isn't even built in C++ is obviously impossible.
> This particular compiler does require bootstrapping, and that's obviously what "the compiler" is referring to in that comment.
You have to pick an option: either it requires bootstrapping, or it doesn’t.
As it’s possible to write the C++20 compiler features in C++11 (or whatever GCC or Clang are written in these days), it factually does not require bootstrapping.
This is going in circles and this is my last comment on it, but here is what I originally replied to:
> So you can never be perfectly bleeding edge as it'd keep you from being able to build your compiler with an older compiler that doesn't support those bleeding edge features.
…as though building the new version of the compiler depended on the features it’s implementing already existing. This is clearly not the case.
> My original point is that you can write a compiler for any language in any language.
A perfectly fine observation on its own—but it's not on its own. It's situated in a conversational context. And the observation is in no way a counterpoint to the person you posted your ostensible reply to.
Aside from that, you keep saying "bootstrapping" as in whether or not this or that compiler implementation strategy "requires bootstrapping". But writing a compiler in different source language than the target language it's intended to compile and using that to build the final compiler doesn't eliminate bootstrapping. The compiler in that other language is just part of the bootstrapping process.
Building your compiler in another language doesn't help at all. In fact, it just makes it worse. Dogfooding C++20 in your compiler that isn't even built in C++ is obviously impossible.