I am trying to do some sequence-for-sequence glyph replacement. As far as I can tell from the Adobe spec, the LHS and RHS of a "sub … by …" rule cannot both contain multiple glyphs; and in any case, luatex 0.70.2-2012091206 (from TeXLive 2012) segfaults if I try.
Hence, I tried the following:
languagesystem DFLT dflt;
languagesystem latn dflt;
lookup A_TO_O {
sub a by o;
} A_TO_O;
lookup U_TO_O {
sub u by o;
} U_TO_O;
feature test {
sub [t]' e by s;
sub [a]' lookup A_TO_O [u]' lookup U_TO_O;
} test;
along with the following LaTeX input:
\documentclass{scrbook}
\usepackage{fontspec}
\setmainfont[FeatureFile=test.fea,RawFeature=+test;]{Times New Roman}
\begin{document}
A test and baud boud bastard.
\end{document}
I'm trying here to replace "te" with "se" in the first rule, and "au" with "oo" in the second.
This does not work; in fact, it doesn't do anything (the first rule doesn't fire). This seems to mean that LuaTeX didn't like it (it does the same thing if I introduce a definite syntax error), but I can't find any error messages.
If I comment out the second rule, the first one fires, and I get "sest" instead of "test" in the output.