Sorry, to be clear, I'm referring to the CPP reimplementation of the Rust compiler that uses GCC as a backend (gccrs).

My concern with fragmentation is that this is essentially a reimplementation of Rust in another language (C++) targeting a different backend (GCC). It's only natural for there to be differences between the two, especially over a long period of time.

There is a separate initiative that may be more in line with what you're thinking which adds GCC backend support for the existing mainstream Rust compiler.