That would have been fantastic. My worry is if we standardized it now, a lot of library code would be unexpectedly dealing with ECANCELED from APIs that previously were guaranteed to never fail outside of programmer error, e.g. `pthread_mutex_lock()`.

Looking at some of my shipping code, there's a fair bit that triggers a runtime `assert()` if `pthread_mutex_lock()` fails, as that should never occur outside of a locking bug of my own making.