Bug#1118385: Non-reproducibility in pdfTeX

On 2026/05/13 8:49, John Collins wrote:

> 2. I don't think this has anything to do with libpng, since I was able to reproduce the same problem on a trivial file, 
> hello.tex, without included graphics:
> 
>     \documentclass{article}
>     \begin{document}
>     Hello
>     \end{document}
> 
> I used the following script to test whether the pdf file changes on successive compilations:
> 
>      for i in 1 2; do
>          pdflatex -interaction=batchmode "\pdfinfo{/CreationDate(D:20260429034606Z)/ModDate(D:20260429034606Z)}\input{hello.tex}"
>          mv hello.pdf hello${i}.pdf
>          sleep 1
>      done
>      diff -sca hello1.pdf hello2.pdf
> 

With

export SOURCE_DATE_EPOCH=`perl -e "print time();"`
export FORCE_SOURCE_DATE=1
for i in 1 2; do
pdflatex -interaction=batchmode "\pdfinfo{/CreationDate(D:20260429034606Z)/ModDate(D:20260429034606Z)}\input{hello.tex}"
mv hello.pdf hello${i}.pdf
sleep 2
done

I obtain the same hello1.pdf and hello2.pdf:
cmp hello1.pdf hello2.pdf
echo $?
0

On the other hand, with

export SOURCE_DATE_EPOCH=`perl -e "print time();"`
export FORCE_SOURCE_DATE=1
for i in 1 2; do
pdflatex -interaction=batchmode "\pdfinfo{/CreationDate(D:20260429034606Z)/ModDate(D:20260429034606Z)}\input{valuators.tex}"
mv valuators.pdf valuators${i}.pdf
sleep 2
done

%valuators.tex
\documentclass{article}
\usepackage{graphicx}
\begin{document}
Hello.

\includegraphics[width=8cm]{valuators.png}
\end{document}

where valuators.png is obtained from
https://salsa.debian.org/fltk-team/fltk1.4/-/blob/main/documentation/src/valuators.png?ref_type=heads

I obtain different valuators1.pdf and valuators2.pdf:
cmp valuators1.pdf valuators2.pdf
valuators1.pdf valuators2.pdf differ: char 421, line 26

Thanks,
Akira