[ninepoints]

Eh, I use them and am quite productive with them. Some of the downsides I don't really buy, for example, the argument regarding allocations. In a typical task engine, you're allocating state per task anyways. Sure you could have custom arenas and such, but you can do that with C++ coroutines also by overriding operator new/delete on the promise object. The lifetime concerns are par for the course when it comes to async stuff (assuming that's how you're using C++ coroutines).

[Conscat]

Generators, which already exist in the stdlib, is an example where we can see heap elision being useful, but is currently unreliable in C++. There is a paper "Explicit Coroutine Allocation" that will likely solve this in C++26. The Clang IR project will also improve HALO for the future of (Clang) C++ projects.