[lltx] Possible glitch in LuaLaTeX present in DVI mode when using Babel

[Daniel Benjamin Miller]

I discuss this here: 
https://tex.stackexchange.com/questions/525898/combining-french-and-greek-babel-does-not-work-in-dvilualatex

For some reason, there is an error when trying to use French and Greek 
Babel support with dvilualatex.

Try running the following, and it will work fine with 
dvilualatex+dvips/dvipdfmx:

|\documentclass[12pt]{article}\usepackage[utf8]{luainputenc}\usepackage[LGR,T1]{fontenc}\input{lgrenc.dfu}\usepackage{lmodern}\usepackage[greek.ancient,main=french]{babel}\title{Ça 
marche?}%\date{} \author{me}\begin{document}\maketitleun, deux, trois 
\end{document}|

Or, try running with English and Greek, and again it works perfectly 
fine once you include Greek text: (Replacing English with any other 
language I tried seems to work, such as Spanish as well)

|\documentclass[12pt]{article}\usepackage[utf8]{luainputenc}\usepackage[LGR,T1]{fontenc}\input{lgrenc.dfu}\usepackage{lmodern}\usepackage[greek.ancient,main=english]{babel}\title{Does 
it work?}%\date{} \author{me}\begin{document}\maketitleone, two, three 
\foreignlanguage{greek}{ἀγαγεῖν}\end{document}|

/But/, if you run it with Greek text in the body and French as one of 
the languages, then dvilualatex will compile a DVI which dvips and 
dvipdfmx both refuse to deal with. Compiling the same TeX document using 
latex+dvips or latex+dvipdfmx works fine, on the other hand.

|\documentclass[12pt]{article}\usepackage[utf8]{luainputenc}\usepackage[LGR,T1]{fontenc}\input{lgrenc.dfu}\usepackage{lmodern}\usepackage[greek.ancient,main=french]{babel}\title{Ça 
marche?}%\date{} \author{me}\begin{document}\maketitleun, deux, trois 
\foreignlanguage{greek}{ἀγαγεῖν}\end{document}|

Which, when run through dvilualatex, seems to complete fine, but returns 
with dvips:

|dvips: ! DVI file contains unexpected command (131)|

and with dvipdfmx:

|dvipdfmx:fatal: DVI opcode 254 only valid for XeTeX|

So what gives? dviasm indicates that the DVI produced is not valid. Note 
that the same issue will arise even if French is not the main language, 
so long as it is one of the loaded languages and Greek is used in the 
text. So the English example will break if hte language line is changed 
to french,greek.ancient,main=english.

Is this a glitch with LuaTeX? Or with Babel? Is there a possible workaround?

DBM


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