Actually, C++'s STL is in a weird situation, compared to the standard library in other languages, because the STL is a spec, not an implementation. And there are as many implementations of the STL as there are compilers. This might arguably happen if there were multiple Rust compilers, though. Anyways, the result on the C++ STL is that in many cases, the same types have different performance characteristics on different platforms, or worse, different behavior/bugs.