Unable to print ligature-free smallcaps

[priyadarshan]

When I installed the latest version of luaotfload, I started having issues with smallcaps.

No matter what I do, smallcaps are being printed with ligatures, even when instructed otherwise.

The exact situation is described on this tex.stackexchange.com question by user gsl.

Basically, with new version I am unable to switch off ligatures when using smallcaps.

I am copying from that question, as I could not describe better:

The following MWE is using Minion, but I tried with many similar fonts: Dante, Merlo, Caslon, etc.

% !TEX TS-program = LuaLaTeX

\documentclass{article}
\usepackage{fontspec}
\defaultfontfeatures{Ligatures={NoRequired, NoCommon, NoContextual}}

\newfontfamily\MinionSmallCaps
[Ligatures={NoRequired, NoCommon, NoContextual},
Letters={UppercaseSmallCaps,SmallCaps},
LetterSpace=80,WordSpace=3]
{MinionPro}

\begin{document}
\addfontfeatures{Ligatures={NoRequired, NoCommon, NoContextual}}
\MinionSmallCaps Test is here [Minion]
\end{document}

Environment:

This is LuaTeX, Version beta-0.80.0 (TeX Live 2015) (rev 5238) 
fontspec-luatex.sty    2015/09/24 v2.4e
fontspec-patches.sty    2015/09/24 v2.4e    
luaotfload.sty    2015/12/09 v2.6

Results:

I am able to have the desired result, using the same text and same font, using InDesign:

InDesign settings:

How can one completely switch off ligatures while using smallcaps with LuaLaTeX?

---

Edit 1

Writing "testate" and using "Minionpro", as suggested by @ulrike-fischer throws an error:

luaotfload-letterspace.lua:445: You cannot set field prev.next in a node of type glyph

The results is this one:

---

Edit 2

Using a similar free font, Cardo, with

\CardoSmallCaps Testate is here [Cardo]

The result is this one:

The ligatures are off, although the Letters={UppercaseSmallCaps,SmallCaps} directive seems not to be respected perfectly.

---

Edit 3

As user egreg said,

It really seems a bug in luaotfload, if not in LuaTeX.

---

Edit 4
User egreg said

I write estate with Linux Libertine as font, I get no letter spacing in TAT, but an error with Minion Pro. So there's some problem when letters are kerned.

[priyadarshan]

This issue could be related to #309, although it is not quite similar.

[phi-gamma]

···<date: 2015-12-17, Thursday>···<from: Priyadarshan>···

How can one completely switch off ligatures while using smallcaps with LuaLaTeX?

What do you mean “switch off” -- have you tried defining the font
without the “liga” feature?

Writing "testate" and using "Minionpro", as suggested by @ulrike-fischer throws an error:

luaotfload-letterspace.lua:445: You cannot set field prev.next in a node of type glyph

Probably my fault, I’ll investigate. A lot of things changed on
this front, causing node handling to be more delicate. Thanks for
reporting.

Best,
Philipp

[phi-gamma]

···<date: 2015-12-17, Thursday>···<from: Priyadarshan>···

Writing "testate" and using "Minionpro", as suggested by
@ulrike-fischer throws an error:

luaotfload-letterspace.lua:445: You cannot set field prev.next in a node of type glyph

Interestingly, that error only occurs with the Luatex in Texlive.
With 0.87.0 it doesn’t.

[phi-gamma]

···<date: 2015-12-17, Thursday>···<from: Priyadarshan>···

Writing "testate" and using "Minionpro", as suggested by @ulrike-fischer throws an error:

luaotfload-letterspace.lua:445: You cannot set field prev.next in a node of type glyph

Ok, that crash is fixed.

[priyadarshan]

Thanks for that. Also, apologies for using Fontspec terminology, while I should have reported this within proper Luaotfload namespace.

[phi-gamma]

This turned out to be a regression in letterspacing. With the
current master the output is this:

[priyadarshan]

Very nice, thank you!

Would you want me to test it with other fonts as well?
Is there going to be a release soon(ish), perhaps even ad interim, ie not still meant for CTAN?
If not, I see from README one could compile it using Make. I could try that way.

Thank you so much for all your work. It is really appreciated, especially so close to the festivities!

[phi-gamma]

@priyadarshan New release has been uploaded. Please test and reopen if
necessary. We’ll continue next year.

[priyadarshan]

I will. Thank you so much for your work. Happy holidays!