Incompatibility between doclicense and silence (Regression)

[thbde]

The following does not fully compile with pdftex, but hangs in a endless loop:

\RequirePackage{silence}
\documentclass[a4paper]{report}
\usepackage[type={CC},modifier={by},version={4.0}]{doclicense}

\begin{document}
Thanks for your great work with doclicense!
\end{document}

Output of \listfiles:

• silence.sty 2012/07/02 v1.5b
• doclicense.sty 2016/04/24 v1.5.0

Expected behavior: Well, the example above compiles and I get a pdf.

Observations:

1. It seems to be a regression:
   1. doclicense.sty 2016/04/24 v1.5.0 # works (used in my overleaf project)
   2. doclicense.sty 2021/03/13 v2.3.0 # does not work, hangs (recent local TexLive installation)
2. silence seems to be in general considered as outdated. However, it seems to be the only way to block warnings in third party code that I cannot influence (like in ifplatform). Therefore, getting rid of silence is not a suitable option.
3. Google finds: https://www.mrunix.de/forums/showthread.php?77506-Probleme-mit-dem-doclicense-und-silence-Paket with a discussion + fix that compiles. See below.
4. Apparently, it seems to be an issue in silence (one may find more evidences by searching for silence and Terminator or by searching for silence and hyperref. Now we could argue that silence should be fixed (and I would in general agree). However, silence seems to be not updated anymore (which is a very weak argument, but still) and doclicense worked with silence in older versions of doclicense. Avoiding regressions could maybe a strong argument for an adaption of doclicense.

With the change from: https://www.mrunix.de/forums/showthread.php?77506-Probleme-mit-dem-doclicense-und-silence-Paket, the example from above compiles successfully.

\RequirePackage{silence}
%the next 3 lines are new
\makeatletter
\def\sl@Terminator{\null}
\makeatother
\documentclass[a4paper]{report}
\usepackage[type={CC},modifier={by},version={4.0}]{doclicense}

\begin{document}
Thanks for your great work with doclicense!
\end{document}

[ypid]

This seems to be caused by hyperxmp actually, maybe even the interaction between hyperref and hyperxmp. I am working on a warning similar to #69.

\RequirePackage{silence}
\documentclass[a4paper]{report}
\usepackage[hyperxmp=false,type={CC},modifier={by},version={4.0}]{doclicense}

\begin{document}
Thanks, you are welcome :)
\end{document}

[ypid]

I propose #83. But in your case, that results in a new warning from doclicense. I have the feeling that you don’t like warnings. Ideally, this would be fixed in hyperxmp or silence. They are both under the LaTeX Project Public License which actually defines how a new maintainer can take over maintenance. Please consider that.

[thbde]

Thank you very much for considering the issue. I really do not feel comfortable to put a burden here on doclicense as the issue seems to be caused by silence. The regression was the strong argument from my side as it could be frustrating for non-experts if they come back to a latex document and it hangs during compilation.

Regarding the change: I am not a Latex expert in detail. Maybe it could be possible to detect the issue on a "feature-level" instead of a package level? It may be unlikely to be soon, but if the silence package is fixed, then the check here might be wrong. I am honest, I will not remember this check in 10 years.

Other than that, it is a bit unfortunate that we do not get the metadata, but this is no showstopper.

I have the feeling that you don’t like warnings.

Well, point for you :) Warnings serve a purpose and therefore I try to get rid of them (without silencing them...).
Here, I could live with the approach proposed by #83. If I load the silence package, then I could also block this specific warning.

[ypid]

"feature-level" instead of a package level

Good idea but for that, I would need to debug the two packages to find the bug to do this feature or rather bug-level detection. And then I should rather fix the bug. But that is a bit out of scope for me.

So I merge #83 then. This workaround is in the workaround section and I will probably test if the workaround is still needed every other TeXLive release or so.

[thbde]

Ok, I understand. Fine for me. And again thank you very much for taking care of this issue.