Circular dependencies in bindings

[bajtos]

Detect circular class/provider dependencies and fail with a helpful error.

Acceptance criteria

• The fix, make sure to handle both linear dependency hierarchy as well cross-leaf references in a tree of deps and include tests!
• Documentation so that people can find more information about this problem when they see the error message.
• A blog post

[raymondfeng]

WIP at #671

[bajtos]

WIP at #671

#671 adds more than just detection of circular dependencies, most notably withOptions method, and I am not sure we have agreed withOptions is the right approach to take.

@raymondfeng Could you please move the commit for circular dependencies to a standalone pull request?

[bajtos]

@raymondfeng I think the first part was done by #852, could you please confirm?

• The fix, make sure to handle both linear dependency hierarchy as well cross-leaf references in a tree of deps and include tests!

Could you please prioritize the remaining two parts so that we can close this issue as done soon?

• Documentation so that people can find more information about this problem when they see the error message.
• A blog post

[raymondfeng]

See draft docs at loopbackio/loopback.io#588

[raymondfeng]

Implemented by #852

[raymondfeng]

Blog: https://github.com/strongloop/strongloop.com/pull/109