[tex-hyphen] hyphenation with ligatures in input

[Stephan Hennig]

[CC: lualatex-dev at tug.org
Please reply to tex-hyphen at tug.org]

Hi,

in the following, I'm only considering LuaTeX with UTF-8 encoded input.

When a ligature character, e.g., fi, is already present in the input
stream, LuaTeX won't hyphenate that word correctly.

\showhyphens{financial financial}
\bye

> This is LuaTeX, Version beta-0.76.0-2013120414 (rev 4627)  (format=luatex 2013.12.11)  15 JAN 2014 18:17
> [...]
> [][] \tenrm fi-nan-cial finan-cial


The same is true for LuaLaTeX, by default, or when activating US
hyphenation patterns with either Babel or Polyglossia.

However, when activating UK hyphenation patterns the word containing the
ligature is also hyphenated (code attached at the end).

> This is LuaTeX, Version beta-0.76.0-2013120414 (rev 4627)  (format=lualatex 2013.12.11)  15 JAN 2014 18:20
> [...]
> [][] \EU2/lmr/m/n/10 fin-an-cial fin-an-cial


Why is that?  I can't find an fi ligature character neither in UK
hyphenation patterns nor in the exception list (hyph-en-gb.pat.txt,
hyph-en-gb.hyp.txt).

What set of (ligature) characters is handled such a special way?

Does the handling depend on the fonts used?

Best regards,
Stephan Hennig


% -*- coding: utf-8 -*-
\documentclass{article}
%\usepackage[USenglish]{babel}
%\usepackage[UKenglish]{babel}
\usepackage{polyglossia}
%\setmainlanguage[variant=us]{english}
\setmainlanguage[variant=uk]{english}
\begin{document}
\showhyphens{financial financial}
\end{document}