Hi,
here are two bugs:
* in pdftex, \letterspacefont does not disable the ligatures, but this
is what happens in luatex.
* neither \tagcode nor \pdfnoligatures seem to have any effect (for
non-letterspaced fonts, that is).
Example:
\input luaotfload.sty
\font\x="Latin Modern Roman:+liga;+tlig" at 12pt
\tagcode\x`\f=-1 % no effect
\pdfnoligatures\x % ditto
\x fi --
\letterspacefont\y\x 100 % killing the ligatures
\y fi --
\bye
Best regards,
--
Robert