The most interesting thing about Fish 4.0.0 for most people will be that it is now written in Rust, which they talk about here [1]. Looking forward to testing it out and seeing if there are any noticeable differences.
Stylo was tried twice in C++ before the Rust attempt, and it never worked out, because the threading was too hard to get right. In theory you could have done it. But in theory, theory and practice are the same, but in practice, they’re different.
("a few" might be off by pre-pandemic amount of years, my memory is a bit fuzzy there)
It's progressed in the sense of like, the Unsafe Code Guidelines and opsem teams are hammering down the exact semantics still, and have made a lot of progress. I'm not aware of any actual optimization work taking place off of it yet, which would make sense given that it's not all fully hammered out yet.
I also might have been handwaving towards how restrict kept having to be turned off because it was broken, meaning very few C or C++ codebases seem to use it at all, whereas virtually every Rust reference has it on. It's been back on for a while now.
Thank for the general update! I might not write any Rust code myself, but I do enjoy quite a few programs written in it, so I was hoping to hear there was more progress for the sake of the developers behind those programs. But I can also imagine that these kind of things take time to figure out properly, to avoid repeating mistakes of previous languages (and that's before we even get to the task of implementing anything).
Wish the people working on these issues all the best, and looking forward (from the sidelines) to what eventually comes out of it!
But for the end product, I err on the safety side for sure.
I am no rust programmer though, and I don't think the rust code was very idiomatic.
But then again I apparently write c++ like a common lisp programmer...