[latex3-commits] [git/LaTeX3-latex3-latex2e] hotfix/gh422: Make alphabetic characters in \@filelist catcode 11 (5dd39147)

[PhelypeOleinik]

Repository : https://github.com/latex3/latex2e
On branch  : hotfix/gh422
Link       : https://github.com/latex3/latex2e/commit/5dd391479f2df699ef562d46e0c77116c1f9ab28

>---------------------------------------------------------------

commit 5dd391479f2df699ef562d46e0c77116c1f9ab28
Author: PhelypeOleinik <phelype.oleinik at latex-project.org>
Date:   Mon Nov 23 18:04:30 2020 -0300

    Make alphabetic characters in \@filelist catcode 11


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5dd391479f2df699ef562d46e0c77116c1f9ab28
 base/ltfilehook.dtx | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/base/ltfilehook.dtx b/base/ltfilehook.dtx
index 584aa9ff..a2da6c91 100644
--- a/base/ltfilehook.dtx
+++ b/base/ltfilehook.dtx
@@ -712,9 +712,28 @@
 }
 %    \end{macrocode}
 %
+% Before adding to the file list we need to make all (letter) characters
+% catcode~11, because several packages use constructions like
+% \begin{verbatim}
+% \filename at parse{<filename>}
+% \ifx\filename at ext\@clsextension
+%   ...
+% \fi
+% \end{verbatim}
+% and that doesn't work if \cs{filename at ext} is \cs{detokenize}d.
+% Making \cs{@clsextension} a string doesn't help much because some
+% packages define their own \cs[no-index]{<prefix>@someextension} with
+% normal catcodes.  This is not entirely correct because packages loaded
+% (somehow) with catcode~12 alphabetic tokens (say, as the result of
+% a \cs{string} or \cs{detokenize} command, or from a \TeX{} string like
+% \cs{jobname}) will have these character tokens incorrectly turned into
+% letter tokens.  This however is rare, so we'll go for the all-letters
+% approach (grepping the packages in \TeX{} Live didn't bring up any
+% obvious candidate for breaking with this catcode change).
 %    \begin{macrocode}
 \def\@input at file@exists at with@hooks#1{%
-  \@addtofilelist{\unqu at tefilef@und#1\@nil}%
+  \edef\reserved at a{\unqu at tefilef@und#1\@nil}%
+  \@addtofilelist{\string at makeletter\reserved at a}%
   \UseHook{file/before}%
 %    \end{macrocode}
 %    The current file name is available in \cs{CurrentFile} so we use