Fix #14059 (PDF build crash with French since August 2025 LaTeX)

[jfbu]

Fix #14059

[mitya57]

Thank you for the very quick fix!

[jfbu]

Thank you for the very quick fix!

You are welcome, I since could ascertain that the last version of `babel-french` I had on my current system prior to an early September 2025 update was `2024-07-25 v3.6c` and it did contain the definition of `\localleftbox` so I am pretty confident that the problem arose only this last August 2025, but I can't be sure because there is no public repository for `babel-french` and in the tradition of most ancient LaTeX packages its documentation does not allow to track these things (and usually it will only give in its user level PDF doc a version number when a commented changed happened but not the associated release date; the `dtx` may contain more information, but nothing 100% certain can be concluded from it at this stage after the split).

[mitya57]

I believe that in Debian it regressed when our TeX Live version was updated from 2025-03-09 snapshot (which was still TeX Live 2024) to 2025-07-27 (which is 2025). So if it's triggered by a change in babel-french, then it happened within that time range.

There is also a “Change History” section in frenchb.pdf, but it does not say anything about \localleftbox.

[jfbu]

@mitya57 Thanks for info!

In view of this 2025-06-28 announcement we learn that 2025-06-28 was the Doomsday date 😄, where babel-french split into a frozen frenchb3.dtx for pdflatex and xelatex and an evolving frenchb.dtx for lualatex, which bumps its major version number to 4. It is possible but not probable that the \localleftbox had disappeared earlier from the pdflatex code, and similarly possible but even less probable that it was removed only later.

On a laptop which I updated during the summer but only rarely backed up, the v3.7d of 2025-07-25 had already lost the \localleftbox for pdflatex. I should not have entitled my commit with a reference to August 2025, but finding this extra information has cost me some time that I did not have earlier.

An examination of the SVN sources of TeXLive could help confirm 2025-06-28 as the release date when \localleftbox was dropped from the pdflatex code.

[mitya57]

An examination of the SVN sources of TeXLive could help confirm 2025-06-28 as the release date when \localleftbox was dropped from the pdflatex code.

Thanks for the pointer. It probably happened at the time of the split:
https://svn.tug.org:8369/texlive?revision=75643&view=revision

In particular, this part of the diff shows that \providecommand\localleftbox[1]{} was removed:
https://svn.tug.org:8369/texlive/trunk/Master/texmf-dist/tex/generic/babel-french/french.ldf?r1=75642&r2=75643#l1273

[jfbu]

@mitya57 Yes you are right. For some reason (I updated my Firefox right now and I notice a few behavorial change which I have to understand), I can not load the diff you linked to but https://svn.tug.org:8369/texlive/trunk/Master/texmf-dist/source/generic/babel-french/frenchb.dtx?pathrev=75643&view=log works for me which says that the previous update was r71907 from one year earlier, and checking https://svn.tug.org:8369/texlive/trunk/Master/texmf-dist/source/generic/babel-french/frenchb.dtx?r1=71907&r2=75643&pathrev=75643 I see that indeed the \providecommand\localleftbox[1]{} disappeared only at the time of the split. Anyway, it was my mistake initially to copy over the upstream code, and I should think of a more stable solution, but as a quick fix I simply re-added the legacy \providecommand. (I could have added an \ifdefined rather where the \localleftbox is used but this is a bit less efficient). Note that the .dtx file are only the source files which combine code and code comments (even possibly user manual), but the documentation of frenchb and the announcement it made strangely refers to the .dtx themselves.

[mitya57]

Strange, my link opens fine for me (also in Firefox).

Anyway, here is the relevant patch fragment:

--- trunk/Master/texmf-dist/tex/generic/babel-french/french.ldf	2025/06/29 20:26:16	75642
+++ trunk/Master/texmf-dist/tex/generic/babel-french/french.ldf	2025/06/29 20:27:47	75643
@@ -1908,8 +1271,7 @@
 \newcommand*{\FBfnmarkspace}{\kern .5\fontdimen2\font}
 \def\@footnotemarkFB{\leavevmode\unskip\unkern
                      \protect\FBfnmarkspace\@footnotemarkORI}%
-\providecommand\localleftbox[1]{}
-\AtBeginDocument{%
+\newcommand*{\FBfootnote@switch}{%
   \@ifpackageloaded{footnotebackref}%
       {\FBFrenchFootnotesfalse
        \PackageWarning{french.ldf}%

[jfbu]

@mitya57 We can say that we will have documented this fully 😄, thanks a lot for your help. As per the link, maybe it did not help that I was downloading in background a macos system update over a 4G connection. I will merge some fix to the #14060 CHANGES entry regarding to when the problem arose. Many thanks for your help throughout this.