The C FFI worries me because if I choose Rust for our project I'll need to interface a huge number of C / C++ libraries with the Rust core. OTOH, Mozilla seems to be doing fine mixing Rust with C++.
Its not that it doesn't work, but rather that it is not guaranteed to work, and the design is basically a pile of duck tape. For example, you can use Rust arrays in a C FFI declaration, but that won't do what you think it does:
The C FFI worries me because if I choose Rust for our project I'll need to interface a huge number of C / C++ libraries with the Rust core. OTOH, Mozilla seems to be doing fine mixing Rust with C++.