Glad I am not using FreeBSD

It does raise the question as to why FreeBSD would still be relying on CVS in this day and age...

That said Modula-3 seems to be a saner language than C or C++ (I say this as a professional C++ developer who have worked in safety critical hard real-time for over a decade, and am now a huge fan of Rust).

Looking at the examples on Wikipedia for Modula-3 it reminds me of a mix of Pascal/Ada with the upper case of Fortran. I prefer something a bit less verbose and more functional personally, but it sounds like it is at least somewhat memory safe.

At the time it was probably a sensible choice (the other options would be been Ada or a scripting language I guess?). Now it will suffer from the lack of an ecosystem, which means fewer people who understand the code, and less available libraries (meaning you have to write everything yourself).

- Is there "buy in"? Do the users of CVSup want Rust CVSup, or does it just go in the pile of "Tasks we set for Rust developers as a prank" when you're finished?

- Is the present behaviour of CVSup well characterised, documented, maybe there are even unit tests so that we can tell whether our Rust CVSup is in fact a working replacement ?

- Is there something CVSup doesn't do that a Rust CVSup could fix? Or equally something it does do that it shouldn't?

My guess is that in fact these are merely "top bants" and in practice there is no actual interest in a Rust CVSup so this exercise would be futile.

Notice the linked Perforce page just tells you FreeBSD hasn't used Perforce for years. This is legacy documentation, most of FreeBSD's documentation can be described as "Somebody wrote this, nobody is in charge of making sure it's still correct and we don't keep records of what it's about or why it was written. Good luck". Maybe CVSUp is exciting new software just introduced, maybe it is being replaced with a C equivalent for platform compat reasons. Maybe both those stories are long obsolete.

That's not the request though. The request is for someone interested in getting language A adopted in base to reimplement a tool written in an obscure language B, that has not seen continued development in nearly 15 years, nor has ever seen significant adoption.
So it would seem absolutely fair to assume that barely anybody knows the language B, which means the request is actually to learn this language to a fairly competent level. Which somehow will demonstrate that the value of adopting the language A?

That article is there for historical reasons (as noted in the banner at the top), and not actually relevant nowadays. FreeBSD has migrated from CVS --> SVN --> Git, the latest migration done around 2020.