One problem of Rust vs C, I rarely see mentioned is that Rust code is hard to work with from other languages. If someone writes a popular C library, you can relatively easily use it in your Java, D, Nim, Rust, Go, Python, Julia, C#, Ruby, ... program.
If someone writes a popular Rust library, it's only going to be useful to Rust projects.
With Rust I don’t even know if it’s possible to make borrow checking work across a language boundary. And Rust doesn't have a stable ABI, so even if you make a DLL, it’ll only work if compiled with the exact same compiler version. *sigh*
The reason you rarely hear that mentioned is because basically every programming language is hard to work with from other languages. The usual solution is to "just" expose a C API/ABI.
Of course, C API/ABIs aren't able to make full use of Rust features, but again, that also applies to basically every other language.
I don't think they should be defined in terms of any programming language. They should be defined in terms of the architecture - bits, bytes, words and instructions, along with semantics of use. Like we do with networking protocols and file formats.
If someone writes a popular Rust library, it's only going to be useful to Rust projects.
With Rust I don’t even know if it’s possible to make borrow checking work across a language boundary. And Rust doesn't have a stable ABI, so even if you make a DLL, it’ll only work if compiled with the exact same compiler version. *sigh*