\includegraphics comma in alt key using xkeyval

[lstonys]

Brief outline of the bug

xkeyval package redefines \setkeys and then it breaks \includegraphics alt key having comma inside. Image is not shown.
If I run \setkeys{Gin}{alt={Alternative, text for image.}} outside of \includegraphics I can get alt text.
graphicx loads keyval so maybe it could copy \setkeys and use it inside \includegraphics to be sure that other packages will not spoil this command:

...
\RequirePackage{keyval,graphics}
\let\keyval@setkeys\setkeys
...
\def\Gin@ii[#1]#2{%
       ...
       %\setkeys{Gin}{#1}%
       \keyval@setkeys{Gin}{#1}%
       ...
     \fi}
\long\def\Grot@box@kv[#1]#2#3{%
     ...
    %\setkeys{Grot}{#1}%
    \keyval@setkeys{Grot}{#1}%
    ...
  \@end@tempboxa}
...

Minimal example showing the bug

\RequirePackage{latexbug}       % <--should be always the first line (see CONTRIBUTING)!
\documentclass{article}
\usepackage{graphicx}
\usepackage{xkeyval}

\makeatletter
\define@key{Gin}{alt}{\def\MyText{#1}}
\makeatother

\begin{document}
\setkeys{Gin}{alt={Alternative, text for image.}}
\show\MyText

\includegraphics[alt={Alternative, text for image.}]{hand}
\end{document}

[josephwright]

If reproducible, this would be a bug in a third-party piece of code: as such, it should be reported to the appropriate maintainer. This is flagged up by latexbug.

[lstonys]

I see that other issues for graphicx was written here in this repository so I just have a suggestion for @davidcarlisle how to make graphicx it a bit safer.

[davidcarlisle]

@lstonys This is the correct repository for graphicx issues but as the latexbug log would have warned you, you should make an example not using third party packages. In this case, keyval was written at the same time as graphicx and explicitly extracted to a separate package to make the code shareable. It can not be right to copy small fragments back 30 years later because some contributed package breaks the code. The core code would become unmaintainable if we adopted a policy of working around such bugs. Please report this to the maintainer of xkeyval

[u-fischer]

I think that is something that could be fixed in graphicx. It uses \toks@ to store \Ginclude@graphics{#2} and then calls \setkeys which somewhere changes \toks@.

If I use a dedicated toks register, the document compiles as expected:

\documentclass{article}

\usepackage{xkeyval}
\usepackage{graphicx}

\begin{document}

\makeatletter
\newtoks\Gin@toks@

\def\Gin@ii[#1]#2{%
    \def\@tempa{[}\def\@tempb{#2}%
    \ifx\@tempa\@tempb
      \def\@tempa{\Gin@iii[#1][}%
      \expandafter\@tempa
    \else
     \begingroup
       \@tempswafalse
       \Gin@toks@{\Ginclude@graphics{#2}}%
       \setkeys{Gin}{#1}%
       \Gin@esetsize
       \the\Gin@toks@
     \endgroup
     \fi}
\makeatother     
\includegraphics[alt={blub,blub}]{hand}

\end{document}

@lstonys Unreladed but be aware that the tagging code (re)defines the alt-key to set alternative text, so please do not overwrite it when tagging is active.

[lstonys]

@u-fischer, I was adding alt-text to tagged pdf that's why I got this bug

[davidcarlisle]

@u-fischer arguably true, but you'd have to change the register everywhere not just there \Gin@resize, the scale and other keys, also epsfig package. I worry something would break, it would seem safer to assert that \toks@ is part of the interface here.

[u-fischer]

@davidcarlisle well yes, but I don't think we can leave it as it is. It wouldn't be good if with tagging graphics suddenly disappear. Something like this seems to fix at least this issue, so perhaps we should add an firstaid?

\documentclass{article}
\usepackage{xkeyval}
\usepackage{graphicx}

\begin{document}

\makeatletter
\newtoks\XKV@TEMPFIX@toks
\def\@s@lective@sanitize[#1]#2#3{%
  \begingroup
    \count@#1\relax\advance\count@\@ne
    \XKV@toks\expandafter{#3}%
    \def#3{#2}\@onelevel@sanitize#3%
    \edef#3{{#3}{\the\XKV@toks}}%
    \expandafter\@s@l@ctive@sanitize\expandafter#3#3%
    \expandafter\XKV@tempa@toks\expandafter{#3}%
  \expandafter\endgroup\expandafter\XKV@TEMPFIX@toks\expandafter{\the\XKV@tempa@toks}%
  \edef#3{\the\XKV@TEMPFIX@toks}%
}
\makeatother     

\makeatletter
\includegraphics[alt={blub,blub}]{hand}

\end{document}

[davidcarlisle]

I've re-opened.

This should be fixed in\xkeyval (to not change \toks@) but as @u-fischer says we could change (all uses of) \toks@ in graphics to a declared register, if that doesn't break other contrib packages, to be checked....

[lstonys]

Maybe you already have any solution?

[davidcarlisle]

@lstonys there are solutions in the comments above which we may add but fundamentally this is a xkeyval issue, did you report it there?

[lstonys]

No, I couldn't find Hendri Adriaens email.