Subject: Re: bug#79397: 29.3; ffap-latex-mode should be modified after upstream kpsewhich update

From: Eli Zaretskii <[email-masked]>
Date: Sat, 13 Sep 2025 11:48:00 +0300

> From: Leo Stein <[email-masked]>
> Date: Sat, 6 Sep 2025 14:23:03 -0500
> 
> ffap-latex-mode in ffap.el uses the executable kpsewhich if available.
> Before a recent change to kpsewhich, the executable would report
> possible paths, one per line, with no blank lines. Following svn
> revision 73462 in texlive's tree (which is included in TeX Live 2025;
> see lines 959-966 at
> https://svn.tug.org:8369/texlive/trunk/Build/source/texk/kpathsea/kpsewhich.c?r1=69416&r2=73462),
> the new behavior of kpsewhich is to output a blank line for each
> input file which was not found.
> 
> The behavior in ffap-latex-mode is to simply take the first line from
> the temp buffer that recieves the output. Previously, this would either
> be a valid path, or the buffer would be empty. With the new behavior,
> the buffer could be non-empty, with various blank lines, and the first
> valid path might follow after some blank lines.
> 
> ffap-latex-mode can easily be patched by just removing blank lines from
> the temp buffer. However I don't know if that is the idiomatic approach;
> please teach me the ways!

It might be simpler to look for the first non-empty line.

Feel free to suggest a patch along these lines, and thanks.