correct label data

[u-fischer]

In beamer anchors are created by the \label command, have the name of the key and \ref{key} references the anchor key.

The data written to the aux-file doesn't reflect that. Beamer always writes Doc-Start as anchor.

\newlabel{blub}{{2}{2}{}{Doc-Start}{}}

This makes it hard for other code to create correct hyperlinks, for example \hyperref doesn't work, but also zref-clever has problems https://tex.stackexchange.com/q/730782/2388 (and the tagging code needs the anchors too)

I suggest to update \@currentHref before issuing the label:

\documentclass{beamer}

\makeatletter
\def\beamer@label<#1>#2%
 {\alt<#1>{\gdef\@currentHref{#2}% <-- new
   \beamer@origlabel{#2}\beamer@nameslide{#2}}{\beamer@dummynameslide}}
\makeatother

\begin{document}

\begin{frame}
First page
\end{frame}


\begin{frame}
\label{blub}
Goal
\end{frame}

\begin{frame}
\hyperref[blub]{jump}
\end{frame}

\end{document}

[samcarter]

@u-fischer Thanks a lot!

[gusbrs]

Thank you both!

[u-fischer]

@samcarter It could be that it is needed here too

\def\beamer@label@in@display<#1>#2{\alt<#1>{\beamer@origlabel@in@display{#2}\beamer@nameslide{#2}}{\beamer@dummynameslide}}

but I have no test files to check.

[samcarter]

@samcarter It could be that it is needed here too

\def\beamer@label@in@display<#1>#2{\alt<#1>{\beamer@origlabel@in@display{#2}\beamer@nameslide{#2}}{\beamer@dummynameslide}}

but I have no test files to check.

With the following, the aux file would contain equation.1. Does this need changing?

\documentclass{beamer}

\begin{document}

\begin{frame}[label=foo]
content...
\end{frame}

\begin{frame}
  \begin{equation}
  x\tag{quack}\label{key}
  \end{equation}
\end{frame}

\begin{frame}
content...
\end{frame}


\begin{frame}
\eqref{key}
\end{frame}


\end{document}

[u-fischer]

yes. If you use \hyperref[key]{key}, it will complain about the missing destination equation.1

[samcarter]

@u-fischer added 8ba8b9f

[u-fischer]

thanks. And thinking about it, it is probably better to expand the key name, so \xdef\@currentHref. For beamer it shouldn't matter, as the label is written directly, but perhaps someone looks later at \@currentHref.

[samcarter]

done :)

[u-fischer]

let's hope that not nobody uses something in the \label key stuff that doesn't like an xdef. But in view that beamer uses it since a long type for destination names one can hope that it is safe. If not one will have to add some protections ...

[gusbrs]

@samcarter Might I add a (related) request here? When you set a label as in:

\begin{frame}[label=foo]
content...
\end{frame}

The \@currentcounter is not set for foo. I presume it would be framenumber. I don't know when, where or how this is stepped. But, could a proper \@currentcounter value be made available for it?

EDIT: With the caveat that my beamer acquaintance is very limited, \refcounter appears to be the place that sets label data for it. So something like?:

\def\refcounter#1{\edef\@currentcounter{#1}%
  \protected@edef\@currentlabel%
  {\csname p@#1\endcsname\csname the#1\endcsname}}%

EDIT 2: I also see a couple of direct settings to \@currentlabel in beamerbaseframecomponents.sty, apparently for footnotes. Corresponding \@currentcounter settings there would also be appropriate, I think.