Cross refs with memoir and beamerarticle broken

[dbosk]

I get the following broken output when using the memoir class with cross-refs enabled:

Turning off cross-refs works, of course.

Adding hyperref to the preamble, makes it work as it should:

Adding cleveref after that also works.

I have no idea why it breaks with memoir without the hyperref package, further investigation pending. I'll put this here for now, it might help someone in the meantime. (Took me a while to figure this out. I realized it must be related to hyperref after recognizing that noweb. prefix in section 2.11 Support for hypertext of /src/tex/support.nw.)

Final note: The code that is broken with memoir works when article is used instead of memoir, i.e. without the hyperref package and cross-refs enabled.

[nrnrnr]

If you get a minimal working example, I'll have a look.

Past experiences with memoir have been gnarly, so no guarantees.

[dbosk]

Trying to make the MWE, I encountered this:

\documentclass[oldfontcommands]{memoir}
\usepackage{noweb}

\begin{document}
@

<<test>>=
print("Hello, world!")
@

\end{document}

Compiling as follows:

noweave -delay -n -x test.nw > test.tex
pdflatex test.tex
pdflatex test.tex

Gives the following error:

! Undefined control sequence.
\nwblindhyperanchor #1->\hypertarget 
                                     {noweb.#1}{\relax }
l.10 ...\nwbegincode{2}\sublabel{NW2dKK4X-Joiug-1}
                                                  \nwmargintag{{\nwtagstyle{...

This seems related. Probably I have another package that originally made it compile without errors, but with the malformed output. To be continued ...

Edit: Checked if hyperref fixes the problem, it does.

\documentclass[oldfontcommands]{memoir}
\usepackage{noweb}
\usepackage{hyperref}

\begin{document}
@

<<test>>=
print("Hello, world!")
@

\end{document}

[dbosk]

%\documentclass[oldfontcommands]{memoir}
\documentclass{article}
\usepackage{beamerarticle}
\usepackage{noweb}

\begin{document}
@

<<test>>=
print("Hello, world!")
@

\end{document}

Seems like the culprit is beamerarticle, not memoir:

Still not exactly the same result as above, so probably another package interplaying. (In this one all refs are broken, in the original only the one in the margin is broken.) To be continued ...

Edit: Just wanted to check if hyperref fixes the problem, it does.

%\documentclass[oldfontcommands]{memoir}
\documentclass{article}
\usepackage{noweb}
\usepackage{beamerarticle}
\usepackage{hyperref}

\begin{document}
@

<<test>>=
print("Hello, world!")
@

\end{document}

[dbosk]

Switching from article to memoir in the last example gets me the same broken output as in the original example.

\documentclass[oldfontcommands]{memoir}
%\documentclass{article}
\usepackage{noweb}
\usepackage{beamerarticle}

\begin{document}
@

<<test>>=
print("Hello, world!")
@

\end{document}

This yields

[nrnrnr]

I've confirmed that the bug occurs using noweave -delay -x.

Running with tracing on, near as I can tell the Beamer package is taking over \hypertarget:

~...\nwblindhyperanchor #1->\hypertarget {noweb.#1}{\relax }
#1<-NWhiacx-Joiug-1

~...\hypertarget ->\beamer@sort \beamerx@\hypertarget {2}

~....\beamer@sort #1#2->\def \beamer@todo {#1}\def \beamer@ospec {}\beamer@args
count =#2\relax \beamer@parseargs 
#1<-\beamerx@\hypertarget 
#2<-2
{\def}
{changing \beamer@todo=undefined}
{into \beamer@todo=macro:->\beamerx@\hypertarget }
{\def}
{changing \beamer@ospec=undefined}
{into \beamer@ospec=macro:->}
{\count327}
{changing \count327=1}
{into \count327=2}
{\relax}

As far as I can tell, noweb is using \hypertarget in accordance with its API. So it might be time to talk to the Beamer people.

[dbosk]

Great, thanks a lot! I should have a look at Beamer and check in with the Beamer maintainer.

Did you also look at the pure memoir case above? There \hypertarget seemed to be undefined. The memoir manual states that it doesn't do any hyperlinking, that's left for other packages such as hyperref. But noweb checks for that, right? Because we don't get that problem with just article. So there should be something that tricks noweb's checks.

The two cases to compare are

\documentclass{article}
\usepackage{noweb}

\begin{document}
@

<<test>>=
print("Hello, world!")
@

\end{document}

and

\documentclass[oldfontcommands]{memoir}
\usepackage{noweb}

\begin{document}
@

<<test>>=
print("Hello, world!")
@

\end{document}