Does the compiler bootstrap version matter though? Taking the principle that compilers should compile on the most easily accessible toolchain, writing the compiler in C++ would be the best option of all. But nobody wants to do that.
According to the notes here[1], it sounds like companies care enough about bootstrapping Rust that they are doing it via mrustc. Which seems pretty extreme and suggests they care... a lot. (This was surprising to me to find out, at least, the degree to which they care. I understand why bootstrapping is itself an important ideal.)
Yeah, if you take the principle further it would be even better to write it in C89 because this language is comparatively easy to write compilers for. But the principle is not absolute and it doesn't stand above everything else.
There are major differences in how easy it is to write compilers in C++ vs C89. There are major differences between C++ and Rust with its ADTs and pattern matching. But are there major differences between, say Rust 1.32 and Rust 1.36? I'd argue no.
There are real use cases like distros wanting to maintain/bootstrap a Rust compiler independently from upstream binaries. The more often these people have to port a compiler, the more troublesome it is for them.
Rust seems like it's the odd one out: Swift is written in C++, Go supports bootstrapping from years old compilers, LLVM does so as well, and GCC has probably some of the best backwards compatibility stories out there.
D has been replacing the C++ code with D, .NET made a major reboot with Rosyln where VB.NET and C# got bootstraped (F# was already bootstrapped), OCaml and Haskell have only the runtime in C due to convinience with everything else bootstraped, FreePascal is bootstraped, OpenJDK has the long term goal of replacing C++ with Java/Graal, Jikes was bootstraped in Java, ...
You are misunderstanding me. I don't have problems with the fact that Rust is bootstrapped, but with the high rate this bootstrapping is happening. That a 12 week old compiler is already considered as too old to compile the newest rustc. This seems wrong.
