Increase type safety

Feel free to reject this as something out of cloudform’s scope:

It’d be great if cf.Fn.Ref() calls failed to compile if the referenced resource doesn’t exist in the template.

I have an example project that deploys an ECS cluster and a service with cloudform: https://github.com/wolverian/ts-ecs-example. From writing it (and from using cloudform in another, private project), one of the biggest pain points I’ve experienced is making sure I give the correct string values to cf.Fn.Ref() and cf.Fn.GetAtt().

I don’t have a concrete suggestion how to implement this, but any ideas are welcome.

[fhewitt]

I strongly recommend to add a linter step (we use cfn-lint) over the CloudForm result for additional validation. It’s not perfect, but this can grab not only resource reference issues, but some other errors too.

[wolverian]

LGTM. I think I prefer the latter approach, as it looks simpler. I’ll play around with this approach a bit and see how it works. I’ll report if I bump into problems. I’d be happy to contribute a PR later, though it’s fine if you implement this before I get around to it. 👍