How much of C++20 standard Circle already supports?

[Shadoware]

Sorry but I didn't find the information of what is currently supported.

I would like to know in what C++ compiler was Circle based? Maybe Clang?

Make simple information like these more obvious.

P.S. I've discussing about Circle in some C++ forums like Reddit and others and it seems the mains complaint is that Circle is not Open Source so people feels unsafe for it's future.

[correaa]

There are several online talks and interviews of Sean Baxter about circle, for example this one: https://www.youtube.com/watch?v=15j4bkipuAg

I could be mistaken, but I think I understood that Circle is not based in other compilers (frontend?).
Sean wrote the parser from scratch.
It generates the intermediate representation for LLVM (and/or for CUDA) from scratch.
From what I see (in my project) Circle is capable of parsing pretty advanced C++, it is almost perfect as far as I can tell.

I have no opinion with respect to the open-source or non-open-source nature of Circle.
As long as the Circle language is well specified (not sure if it is), that would be more important than whether the implementation is open-source; but yes, it would be nice too.