Ideas for extra checks

[Eisenwave]

Checks for \ref and \iref

During review of some papers, it became apparent to me that we could detect a few more common mistakes related to \ref and \iref:

% Space before \iref
Something like \iref{x}

% No non-breaking space before \ref
Found in \ref{x}
See \ref{y}

There are a few pre-existing such mistakes, and once we get rid of those, we could save ourselves some review time.

Checks for \returns et al.

Furthermore, it should be possible (and relatively lightweight) to detect \returns and other such specifications outside of an itemdescr context:

% OK:
\begin{itemdescr}
\pnum
\returns
X.
\end{itemdescr}

% error:
\pnum
\returns
X.

In fact, can't you do that natively on TeX, so that \returns is only available as a command within itemdescr anyway?

Checks for \exposconcept, \libconcept, etc.

Another easy slip-up is the following:

% Mistake
\libconcept{hello<world>}

% OK:
\libconcept{hello}<world>

We should be able to limit the characters that are permitted inside of libconcept and exposconcept, and their def and nc variants.

[jwakely]

[structure.specifications] uses it outside an itemdescr so would need a change.

[jensmaurer]

\iref check: agreed, working on it.

\ref check: The reason why we introduced \iref (which does not use a hard non-breaking space, but an extra penalty) is that our section numbers can get quite long, so hard-preventing a line break is sometimes not optimal.
Ideally, we'd do the same for \ref and "include" the whitespace before the reference inside the \ref definition and make it a line-break penalty, but not an impossibility. ---> no change for \ref
(There are 658 occurrences for "space before \ref".)