Add an option to edoc to return the list of errors and warnings

[robertoaloi]

Is your feature request related to a problem? Please describe.

As part of the Erlang LS project, we would like to add an edoc diagnostics backend that can display documentation warnings and errors to the user directly in the IDE. That would drastically reduce the feedback loop to write Erlang documentation.

Describe the solution you'd like

For that to be possible without duplicating some of the edoc code, it would be great if the edoc high-level API could return the list of warnings and errors. This behaviour could be triggered via a dedicated option, to keep the API backward compatible. The options could be similar to the return_errors and return_warnings of compile:file/2.

Describe alternatives you've considered

Erlang LS could implement a wrapper around the low-level edoc API, intercepting errors and warnings and returning them to the user. This would most likely result in duplicated code and un-necessary maintenance burden.

Additional context

See the original discussion here.

[robertoaloi]

Hi @KennethL @garazdawi are there any plans to pick this?

[KennethL]

We want this to happen but can not promise that we can prioritize it before OTP 25. We are hoping to get a PR for this.