> Passing uncaught exceptions from the coroutine up to the caller is also pretty easy, because it's all synchronous. You just need to wrap it so it can safely travel across the gap

This is also how dotnet handles it, and you can choose whether to rethrow at the caller site, inspect the exception manually, or run a continuation on exception.

> mustn't catch (...)

You could use the same trick used by glibc to implement unstoppable exceptions for POSIX cancellation: the exception rethrows itself from its destructor.

Thanks, that's interesting.