This series was in response to another thread [1] which wanted to make rust mandatory in an upcoming release.
The authors proposal was to instead take the middle ground and use rust as an optional dependency until a later point of time where it becomes mandatory.
The later point of time was decided based on when rust support lands in gcc, which would make things smoother, since platforms which support gcc would also be included.
[1]: https://lore.kernel.org/git/pull.1980.git.git.1752784344.git...
The GCC compiler collection has been hit and miss though. Nobody uses gcj for example. I sort of doubt that they'll be able to implement a good compiler for a language that doesn't even have a standard without that implementation going wildly out of date in the future, just like what happened with Java.
Since OpenJDK was released there isn't much point maintaining GCJ.
There's two different methods by which Rust support can be added to GCC: adding a Rust frontend to GCC and adding a GCC backend to the Rust compiler (rustc_codegen_gcc). The latter approach would not be (as?) susceptible to implementation divergence as an independent frontend.
yep, if git is content with rustc_codegen_gcc, then it's very doable they can require rust in the next few years