Le 09/07/2019 à 13:32, Guenter Milde a écrit :
Dear LyX developers,
recent discussion about failing tests with the linguistics.module led to the
suggestion:
Drop support for XeTeX + TeX fonts + inputenc utf8.
I do not have much knowledge on this.
What is the way forward that we offer for existing documents?
JMarc
Pro
*There is no known case where this combination is required or helpfull.*
LyX follows LaTeX in ceasing to officially support this combination.
Users will not be confused by failing export.
LyX developer resources will not be drained by dealing with confused
users and failing tests.
For power users with special needs, XeTeX + TeX fonts is still
available after setting the input encoding to "ascii" or "utf8-plain".
Con
The combination XeTeX + TeX fonts is disabled also for documents where it
does not currently lead to errors.
(Is there any scenario where this would be a drawback?)
Rationale:
XeTeX is typically used with Unicode "non-TeX" fonts but can also be used with
8-bit TeX fonts. In LyX, the "View other formats > PDF (XeTeX)" toolbar
button and the "Document>View>Other_Formats>PDF (XeTeX) menu entry work also
for document with the "use non-TeX fonts" setting un-checked.
However, XeTeX + TeX fonts is error prone:
* You need "inputenc" to decode utf8 input. Otherwise non-ASCII characters
may result in wrong output, missing characters, or compilation errors.
(See https://www.lyx.org/trac/ticket/9740 for details.)
However, "inputenc.sty" stopped working with XeTeX some years ago.
Therefore, the fix for #9740 forced ASCII as input encoding for the
combination XeTeX+TeX fonts.
* Unfortunately, the ASCII input encoding leads to other problems.
(See https://www.lyx.org/trac/ticket/10600 for details.)
The fix for #10600 tricks "inputenc" to work with XeTeX.
* Still, there are also other packages that fail with XeTeX + TeX fonts.
Since TL18, this includes "expl3.sty" (by the LaTeX team) that is required
by many other packages, some of them auto-loaded by LyX.
Conclusion:
XeTeX + TeX fonts works in some cases but is not officially supported by
LaTeX. Maintaining support in LyX will need continuous effort in testing
and working around problems.
Günter
