Trjtdtk

I am aware that similar questions have been asked a few times. However, none of the answers solved my problem. This Answer says that it is a bug in luaotfload. But I'm already using a newer version (2.80001).

I'm trying to supress ligatures via selnolig package. It works great, but not for text that was set in capitals. Using microtypes DisableLigatures or selnolig package breaklig also has no effect. See MWE:

% !TeX program = lualatex
% !TeX encoding = UTF-8 Unicode
documentclass[%
 a4paper,
 DIV=9,
 fontsize=14pt,
 parskip=half-
]scrartcl

usepackage[ngerman]babel

usepackagefontspec
setmainfontTeX Gyre Termes[%
 Ligatures=Common,
 SmallCapsFeatures=Letters=UppercaseSmallCaps,
]

setkomafontdispositionrmfamily

usepackage[tracking=true]microtype
SetTrackingencoding=*,shape=sc160
usepackage[ngerman]selnolig

RedeclareSectionCommand[%
 font=scshapemdseriesLarge
]section

RedeclareSectionCommand[%
 font=mdseriesLarge
]subsection

begindocument
% Heading set in caps => ligature still present
sectionBerufliche Praxis
Berufliche Praxispar
ff fl fi

% Using breaklig command => ligature still present
sectionBerufbreaklig liche Praxis

% Disabling selnolig => works as expected
selnoligoff
sectionBerufliche Praxis
selnoligon

% No caps => works as expected
subsectionBerufliche Praxis

enddocument

So the selnolig package takes care that ligatures in Berufliche gets suppressed. This is correct. But it does not work for headings with small caps. Adding selnoligoff right before the section seems to be the only way to supress ligatures in headings with small caps? Or have I missed a setting? I'm wondering which package is responsible for this bug.

Here is an automated approach that reconditions the arguments of section to look for specified ligatures, such as fl and to replace them with, for example, fkern0ptl.

In the MWE, look for the lines between makeatletter and makeatother for the approach.

As an aside, I actually used the same method to also increase the default kern of the space character in small-caps section titles.

Shown for ligatures fl and ff. Can easily add more as needed.

EDITED to handle star sections/toc.

% !TeX program = lualatex
% !TeX encoding = UTF-8 Unicode
documentclass[%
 a4paper,
 DIV=9,
 fontsize=14pt,
 parskip=half-
]scrartcl

usepackage[ngerman]babel

usepackagefontspec
setmainfontTeX Gyre Termes[%
 Ligatures=Common,
 SmallCapsFeatures=Letters=UppercaseSmallCaps,
]

setkomafontdispositionrmfamily

usepackage[tracking=true]microtype
SetTrackingencoding=*,shape=sc160
usepackage[ngerman]selnolig

RedeclareSectionCommand[%
 font=scshapemdseriesLarge
]section

RedeclareSectionCommand[%
 font=mdseriesLarge
]subsection

makeatletter
usepackagelistofitems
expandafterdefcsnameflligendcsnamefkern0ptl% fl
expandafterdefcsnameffligendcsnamefkern0ptf% ff
expandafterdefcsname ligendcsnamehspace11pt% INCREASE SPACE KERN
setsepchar % CONCATENATE THE DESIRED LIGATURES WITH || "OR"
letsvsectionsection
renewcommandsection@ifstarstarsectionnostarsection
newcommandstarsection[1]%
 tmptitle#1%
 svsection*tmp%

newcommandnostarsection[2][relax]%
 tmptitle#2%
 ifrelax#1relaxsvsection[#2]tmpelse%
 svsection[#1]tmp%
 fi%

newcommandtmptitle[1]%
 readlistmyligs#1%
 deftmp%
 foreachitemxinmyligs%
 expandafterg@addto@macroexpandaftertmpexpandafterx%
 ifnumxcnt<listlenmyligs[]relax
 expandafterexpandafterexpandafterg@addto@macro
 expandafterexpandafterexpandaftertmp
 expandafterexpandafterexpandafter%
 csnamemyligssep[xcnt]ligendcsname%
 fi
 %

makeatother
begindocument
tableofcontents

hrulefill
section[blah Berufliche]Berufliche Praxis

sectionHoffähige Praxis

subsectionBerufliche Praxis
enddocument

Of course, I shouldn't mention the crazy stuff you can do with this approach. But I will. Adding these lines (and the xcolor package):

expandafterdefcsnameeligendcsnamekern3pttextcolorredekern1pt
setsepchar % CONCATENATE THE DESIRED LIGATURES WITH || "OR"

produces this result:

With a current luaotfload (version 2.96) you can disable the ligatures in the SmallCapsFeatures:

documentclass[%
 a4paper,
 DIV=9,
 fontsize=14pt,
 parskip=half-
]scrartcl

usepackage[ngerman]babel

usepackagefontspec
setmainfontTeX Gyre Termes[%
 Ligatures=Common,
 SmallCapsFeatures=
 Letters=UppercaseSmallCaps,
 Ligatures=CommonOff, %disable ligatures
]

setkomafontdispositionrmfamily

usepackage[tracking=true]microtype
SetTrackingencoding=*,shape=sc160

RedeclareSectionCommand[%
 font=scshapemdseriesLarge
]section

RedeclareSectionCommand[%
 font=mdseriesLarge
]subsection

begindocument

sectionBerufliche Praxis
Berufliche Praxispar
ff fl fi

enddocument