[XeTeX] latin-1 encoded characters in commented out parts trigger log warnings

[Jonathan Kew]

On 21/02/2021 11:12, David Carlisle wrote:
 > I think that should be taken up with the xstring maintainers.

Yes, I would agree this is an xstring problem.

It looks like in an older version the file was utf-8. I suspect someone 
saved it as Latin-1 in the course of editing, probably without realising 
it at the time.

As a workaround you could try

   \documentclass{article}
   \XeTeXdefaultencoding "iso-8859-1"
   \usepackage{xstring}
   \XeTeXdefaultencoding "utf-8"
   \begin{document}
   \end{document}

to change xetex's default while loading the file.

JK

 >
 > I don't think there is any reasonable way to say you can comment out 
parts of a file in a different encoding.
 >
 > The file encoding specifies the byte stream interpretation before any 
tex tokenization
 > If the file can not be interpreted as utf-8 then it can't be 
interpreted at all. Even replacing by U+FFFD
 > is being lenient.
 >
 > David
 >
 >
 >
 >
 > On Sun, 21 Feb 2021 at 11:04, jfbu <jfbu at free.fr 
<mailto:jfbu at free.fr>> wrote:
 >
 >     Hi,
 >
 >     consider this
 >
 >     \documentclass{article}
 >     \usepackage{xstring}
 >     \begin{document}
 >     \end{document}
 >
 >     and call it xexstring.tex
 >
 >     Then xelatex xexstring triggers 136 warnings of the type
 >
 >     Invalid UTF-8 byte or sequence at line 35 replaced by U+FFFD.
 >
 >     Looking at file
 >
 >     /usr/local/texlive/2020/texmf-dist/tex/generic/xstring/xstring.tex
 >
 >     I see that this matches with use of latin-1 encoded characters in
 >     comments.
 >
 >     Notice that it is a not a user decision here to use a latin-1
 >     encoded file.
 >
 >     In fact I encountered this in a file I was given where
 >     xstring package was loaded by another package.
 >
 >     Regards,
 >
 >     Jean-François
 >
 >