This comment from the core team spells it out: https://github.com/fish-shell/fish-shell/pull/9512#issuecomment-1410820102 https://github.com/fish-shell/fish-she

This comment from the core team spells it out: https://github.com/fish-shell/fish-shell/pull/9512#issuecomment-1410820102 https://github.com/fish-shell/fish-shell/pull/9512#issuecomm... > C++ is an old standardized language with multiple implementations, married at the hip to C, an even older even more standardizederer language. Any changes take ages to get to users so we can actually use it. We moved to C++11 in 2016 (some quick calculation shows that's 5 years after the standard was released), and we're still on C++11 because the pain of upgrading is larger than the promises of C++14/17. We needed to backport compilers for our packages until, I believe, 2020. > Having multiple implementations means you always hit the worst of any of them, because you can't dictate which implementation your users use. So we have to deal a lot more with cmake than we would like, sometimes for things as awkward as "which header is this function in". > C++'s string handling is subpar, and it's much too easy to fall into passing raw wchar_t * around (and we don't have access to string_view and that just enables even more use-after-free bugs!). This is annoying, because a shell is almost entirely string handling and unix api wizardry. > The other general issues with C++ (header files, memory safety, undefined behavior, compiler errors are terrible, templates are complicated) are well-known at this point so I'm not going to rehash them. We know them, we have them, we hate them.