C++ strongly depends on the actual implementation quality by leaving a lot of things to implementations. For example, the person leading the coroutine implement

C++ strongly depends on the actual implementation quality by leaving a lot of things to implementations. For example, the person leading the coroutine implementation in clang is very inconsistent on minimizing allocations than the GCC implementations. As an example they implemented a generator system using C++ coroutines that eventually compile down to a single instruction (https://godbolt.org/z/nsTjjGbn4 https://godbolt.org/z/nsTjjGbn4). As a counter argument though, clang's support for coroutines is still buggy and not ready for production use.