You seem to be right -- at least "no diagnostics required" is mentioned a few times in $10.1.5 of N4700. To be honest, my comment is not from the article in the

You seem to be right -- at least "no diagnostics required" is mentioned a few times in $10.1.5 of N4700. To be honest, my comment is not from the article in the example, but from my own experience, and that is mostly with GCC 7.2.