I apologize for being imprecise. We're aware it's more than just ADL or constexpr, but we had insufficient time to address it at this meeting. It's definitely on our radar, we flagged it as a high priority item.
I just submitted a request to join the reflector where I know this is being discussed; nonetheless, information will be published on http://b.atch.se as soon as I have had time to write the contents of new posts.