replace capital ›ẞ‹ with ›ss‹ when using small caps

Question

I like small caps for author surnames.

Until quite recently, capitalized ›ß‹ – a special character that is regularly used in the German alphabet – was replaced by ›SS‹ (in headings, small caps in bibliographies e.g.). Since a capital ẞ has become available in some fonts, it has also become increasingly popular to make use of it, but I don’t like it.

When using the libertine-package to invoke this font-family for the document, it will automatically turn ß to ẞ when using small-caps (or capitals). Is it possible to avoid this globally (text and bibliography) for ›ß‹ and keep the old setting that simply turned it to ›SS‹?

MWE:

\documentclass{scrbook}

\usepackage{biblatex}
\usepackage[ngerman]{babel}
\usepackage{libertine}
\usepackage{fontspec}

\renewcommand*{\mkbibnamefamily}[1]{\textsc{#1}}
\bibliography{bibliographie.bib}

\begin{document}

Johann Heinrich Voß\cite{Voss1800} translated Virgil.

\begin{filecontents}{bibliographie.bib}
  @Book{Voss1800,
    author   = {Voß, Johann Heinrich},
    title    = {Des Publius Virgilius Maro ländliche Gedichte übersetzt und erklärt, Vierter Band},
    year     = {1800},
    location = {Altona},
 }
\end{filecontents}

\printbibliography
\end{document}

E.g, this yields the following bibliography-entry:

Answer 1

I believe it should be a law that any font providing the utterly ugly ẞ character must provide a stylistic set for replacing it with “SS”.

But you're lucky: not with Linux Libertine, but with its (actively maintained) clone Libertinus. It provides the SS04 feature exactly for this.

\begin{filecontents*}{\jobname.bib}
  @Book{Voss1800,
    author   = {Voß, Johann Heinrich},
    title    = {Des Publius Virgilius Maro ländliche Gedichte übersetzt und erklärt, Vierter Band},
    year     = {1800},
    location = {Altona},
 }
\end{filecontents*}

\documentclass{scrartcl}

\usepackage[ngerman]{babel}

\usepackage[defaultfeatures={StylisticSet=04}]{libertinus}

\usepackage{biblatex}
\usepackage{csquotes}

\renewcommand*{\mkbibnamefamily}[1]{\textsc{#1}}
\addbibresource{\jobname.bib}

\begin{document}

Johann Heinrich Voß \cite{Voss1800} translated Virgil.

\textsc{ß} (just to be sure) fiflffi<<``''>>

ẞ

\printbibliography

\end{document}

Production notes.

• I added an explicit \textsc{ß} and an occurrence of ẞ to be sure that the substitution works. Also some of the standard TeX ligatures to see that they are honored.
• I replaced bibliography.bib with \jobname.bib in order not to clobber my files.
• I also replaced \bibliography with \addbibresource and you should do as well. By the way, the file name given as argument to \bibliography should not contain the extension .bib (it can with MiKTeX, but it's not portable).