Go was designed to be easy to use for un-demanding problems. People mostly switch to Go from Ruby, Python, or Java; or from C in places where C was an unfortunate choice to begin with.
Rust is gunning for C++ territory, in places where the greater expressiveness of C++ is not needed or, in cases, not welcome. They would like to displace C (and the world would be a better place if that happened) but people still using C at this late date will typically be the last to adopt Rust.
All these languages are Turing-complete. The difference is in how much work it is to design and write the program, and in whether it can satisfy performance needs.
C++ wins here by being more expressive, making it better able to implement libraries that can be used in all cases. Rust is less capable, but stronger than other mainstream languages.