Policy: How to deal with undecided rules?

[ehuss]

There will likely be many cases where the language team (or other teams) have not decided on how a particular part of the language should work, and we (the spec authors) know that there is ambiguity. How should we handle that?

I think waiting for a response from the lang team (or other teams) could significantly slow things down, and make it difficult to make progress.

Should the spec specifically mention things that are not yet resolved? Should we just not mention them at all, and track those via GitHub issues?