[danabramov]

>given FB doesn't use promises in their internal apps for the most part, I don't see them likely to put in much work solving these problems unfortunately.

This is inaccurate.

The first problem has an issue tracking it (https://github.com/facebook/react/issues/14769) and even a pull request (https://github.com/facebook/react/pull/14853). It’s barely been two weeks since the first release and we’ve been focusing on fixing actual bugs as soon as possible. As I hope you can understand, warnings in tests are a bit less critical and can wait behind production bugs. But we’ll get back to fixing the warnings as soon as possible — maybe even this week.

As for isMounted-like flag. This has nothing to do with Hooks. Classes need exactly the same thing. If you forget it, you’ll likely have both the same kind of warning, and possible race conditions from requests arriving out of order. In longer term we’ll offer a much simpler data fetching integration (read about Suspense) which doesn’t involve effects or lifecycles at all. I think you’ll like it.