Combining French and Greek Babel does not work in dvilualatex

Question

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} \maketitle un, 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} \maketitle one, 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} \maketitle un, 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? And how might I work around this? (I'll note that it seems to work fine with LuaLaTeX in PDF mode, but for the particular case I want to use DVI. And in any case it's a bug — where does it come from???)

Answer 1

The issue has been fixed in babel-french. If you still entounter it, please update your TeX distribution. The following answer should no longer be applied, because the fix will do more harm than good if combined with the fixed babel-french code.

Old answer

As Ulrike Fischer wrote, the problem is the french punctuation code. It is inserted in the "kerning" callback which replaces traditional TeX kerning code, but doesn't apply any kerning.

So even in your first example containing only french, the is a small difference between the LuaLaTeX and the pdfLaTeX version: In the LuaLaTeX version, the kerning in "marche" is missing.

Normally this isn't important in LuaTeX because in LuaLaTeX you normally use OpenType fonts which use another mechanism for kerning, but it becomes significant when you use legacy fonts.

This can be fixed by changing the callback to add a kerning pass:

\documentclass[12pt]{article}
\usepackage[utf8]{luainputenc}
\usepackage[LGR,T1]{fontenc}\input{lgrenc.dfu}
\usepackage{lmodern}
\usepackage[greek.ancient,main=french]{babel}

\directlua{
  luatexbase.add_to_callback("kerning", node.kerning, "TeX legacy kerning")
} 

\title{Ça marche?} %\date{} \author{me}

\begin{document}
\showoutput
\maketitle
un, deux, trois
\end{document}

This not only fixes kerning for legacy fonts but also fixes your problems with DVI files and greek text:

\documentclass[12pt]{article}
\usepackage[utf8]{luainputenc}
\usepackage[LGR,T1]{fontenc}\input{lgrenc.dfu}
\usepackage{lmodern}
\usepackage[greek.ancient,main=french]{babel}
\directlua{
  luatexbase.add_to_callback("kerning", node.kerning, "TeX legacy kerning")
} 

\title{Ça marche?} %\date{} \author{me}

\begin{document}
\showoutput
\maketitle
un, deux, trois

\foreignlanguage{greek}{ἀγαγεῖν}
\end{document}

works fine.

You might wonder why?

The problem with greek text is related to a special character in greek text: The small sigma. It looks differently when it comes as the final character of a word. This is implemented in TeX as a special kind of ligature: The greek font asks TeX to insert a right_boundary "pseudo-character" at the end of every word. Then the font can use kerning and ligature rules for this special right_boundary character to behave differently at the end of the word. After kerning is done, these pseudo-characters are deleted again.

But deleting these characters is also disabled when the kerning callback is overwritten. So in your example containing french and greek text, at the end of every greek word a right_boundary character survives and gets written into the output file. This leads to weird effects because LuaTeX models this character as a glyph node with index -2 and the output formats don't like negative glyph indices. In PDF, this gets written as a 8 Bit unsigned character and therefore translated to index 2^8-2=254. You don't see this in your example, beause the font subset does not contain character index 254, but if you insert a gree \char 254 anywhere in your document, you will see this character appended to every word in PDF output:

\documentclass[12pt]{article}
\usepackage[utf8]{luainputenc}
\usepackage[LGR,T1]{fontenc}\input{lgrenc.dfu}
\usepackage{lmodern}
\usepackage[greek.ancient,main=french]{babel}
% \directlua{
%   luatexbase.add_to_callback("kerning", node.kerning, "TeX legacy kerning")
% } 

\title{Ça marche?} %\date{} \author{me}

\begin{document}
\showoutput
\maketitle
un, deux, trois

\foreignlanguage{greek}{\char 254 ἀγαγεῖν ἀγαγεῖν ἀγαγεῖν ἀγαγεῖν ἀγαγεῖν}
\end{document}

The DVI file format is insanely flexible and does actually specify how to insert glyphs with negative index. So let's look again at the dvips message:

dvips: ! DVI file contains unexpected command (131)

Command 131 is only needed for glyphs of negative index or indices higher than 16777215. Given that dvips only supports 8 bit fonts with glyph indices between 0 and 255, this command is indeed unexpected. For dvipdfmx the problem is similar, it does only support glyph indices up to 16777215, but the message is bit misleading because it tries to just ignore the command byte 131 and tries to read the font index as (invalid) command.

Answer 2

It looks as if the french punctuation code gives an invalid dvi. If I remove the callback it works ok (one should load lmodern after babel, to avoid that the font family is changed):

\documentclass[12pt]{article}
\usepackage[utf8]{luainputenc}\usepackage[LGR,T1]{fontenc}\input{lgrenc.dfu}
\usepackage[greek.ancient,main=french]{babel}
\usepackage{lmodern}
\title{Ça marche?} %\date{} \author{me}
\directlua{luatexbase.remove_from_callback("kerning","frenchb.french_punctuation")}
\begin{document} \maketitle un, deux, trois
 \foreignlanguage{greek}{ἀγαγεῖν} 
 \end{document}

Answer 3

I have no idea of what goes wrong with dvilualatex, but as you end up with 8 bit Type1 fonts anyway, why not stick to latex + dvips? Note that you'll have to move the \title{} command after the \begin{document} in order to get active punctuation working.

\documentclass[12pt]{article} \usepackage[utf8]{inputenc} \usepackage[LGR,T1]{fontenc} \usepackage[greek.ancient,main=french]{babel} \usepackage{lmodern} \begin{document} \title{Ça marche?} \date{} \author{me} \maketitle un, deux, trois \foreignlanguage{greek}{ἀγαγεῖν} \end{document}