@jwakely, please have a look.

I'd [also] say

- A simple call wrapper\iref{func.def} \tcode{fn}
+ A simple call wrapper\iref{func.require} \tcode{fn}

because it is defined there.

@jensmaurer why the standard doesn't refer to definitions by their names? Aren't these mismatches annoying?
Is there some technical difficulty with tracking the subclause of a definition?

@languagelawyer , there is no technical difficulty, and I've recently started to use term.xxx labels for defined terms.

Example: \label{term.odr.use}

But there is no attempt at bulk conversion. I'll address your particular case in a separate pull request.