tlig em dash ligature is broken

[u-fischer]

(moved from dev-luatex)

--- doesn't give an em-dash if there are no spaces around it (but curriously a hyphen before change this).

context doesn't have a problem. The problem is still there in the newest branch (v2.9603-...).
It works with texlive2017 (and the same fontloader), which seems to imply some engine change but older cache content could play a role here too.

\input luaotfload.sty
\font\test={name:texgyreheros:+tlig;}\test

em dashes---these % gives en-dash

em-dashes---these % gives em-dash

en dash--these %ok

\bye

[zauguin]

I can not reproduce the difference in behaviour depending on the hyphen but always get a en-dash. Apart from that, the regression was introduced in c98b44c which only updated the fontloader. Also it can be reproduced using the plain fontloader:

\input plainfontloader.tex
\font\test={file:texgyreheros-regular.otf:+tlig;mode=node;}\test

dashes-these % gives dash

dashes--these % gives en-dash

dashes---these % gives en-dash
\bye

@u-fischer This seems like an upstream bug. I currently do not have a working ConTeXt install to investigate, so I can't tell why ConTeXt isn't affected. Is ConTeXt using mode=node or mode=base for this font?

[u-fischer]

Ah, good, not our fault ;-). With mode=node I see the problem too. I sent a message to the context list, but I don't want to wait until this is fixed, but will try to upload new version anyway.

[u-fischer]

@zauguin it looks as if we should put \automatichyphenmode=1 (or the lua equivalent tex.automatichyphenmode=1 ) somewhere. Do you have suggestion for a sensible place? (Hans will put it in the plain fontloader too, but I don't know yet, where exactly).

[zauguin]

I think the default value of \automatichyphenmode should be made by the format, so in the LaTeX kernel.
If you want to set this in luaotfload through, I think luaotfload-init.lua would be the best location: Add a third entry in init_post_actions.

[u-fischer]

@zauguin I agree, \XeTeXdashbreakstate is set in the format, and so the luatex setting should there be too. I'm just discussing it on the team list.