Lining numbers for footnotes

Question

Referring to this thread: OldStyle Numbers in Body Text Only—Lining Numbers Otherwisem how can I instruct LuaLatex to use lining numbers for \textsuperscript and footnote markers if my font use by default old style numbers and hasn't super- sub-script figures built-in? Thank you

Addendum

This is a very basic MWE

\documentclass[a4paper,12pt]{book}
\usepackage{fontspec}
\usepackage[english]{babel}
\babelfont[english]{rm}[Ligatures=TeX,Numbers={Proportional,OldStyle}]{EBGaramond}

\usepackage[perpage,bottom,hang,stable,norule]{footmisc}
\renewcommand{\footnotemargin}{0.01em}
\renewcommand{\hangfootparskip}{0pt}
\renewcommand{\footnotelayout}{\hspace{1em}}

\begin{document}

text\textsuperscript{abdx 136}

text\footnote{footnote text}

\end{document}

The fact is that my font (which is a test version, not EBGaramond used for my MWE) has not superior and inferior numbers, so I can't use realscript package

Answer 1

You can just manually change the relevant LaTeX macros:

There are two parts: We begin with \textsuperscript. It is defined by default as

\DeclareRobustCommand*\textsuperscript[1]{%
  \@textsuperscript{\selectfont#1}}

We want to use lining numbers, so we have to add \liningnums{...}. We can omit \selectfont because \liningnums will set the font anyway:

\DeclareRobustCommand*\textsuperscript[1]{%
  \@textsuperscript{\liningnums{#1}}%
}

This changes \textsuperscript, but footnotes are not affected yet. The footnote marks are generated by \@makefnmark, which by default is defined as

\def\@makefnmark{\hbox{\@textsuperscript{\normalfont\@thefnmark}}}

On a first glance you might assume that we could have changed \@textsuperscript instead of \textsuperscript to affect this one too, but that is not the case: The \normalfont would have reverted the number style to old-style numbers. So we have to add \liningnums after \normalfont:

\renewcommand\@makefnmark{%
  \hbox{\@textsuperscript{\normalfont\liningnums{\@thefnmark}}}%
}

Put it all together, add some \makeatletter...\makeatother because we used macro names with @, and we get

\documentclass[a4paper,12pt]{book}
\usepackage{fontspec}
\usepackage[english]{babel}
\babelfont[english]{rm}[Ligatures=TeX,Numbers={Proportional,OldStyle}]{EBGaramond}

\usepackage[perpage,bottom,hang,stable,norule]{footmisc}
\renewcommand{\footnotemargin}{0.01em}
\renewcommand{\hangfootparskip}{0pt}
\renewcommand{\footnotelayout}{\hspace{1em}}
\makeatletter
\renewcommand\@makefnmark{%
  \hbox{\@textsuperscript{\normalfont\liningnums{\@thefnmark}}}%
}
\DeclareRobustCommand*\textsuperscript[1]{%
  \@textsuperscript{\liningnums{#1}}%
}
\makeatother

\begin{document}

text\textsuperscript{abdx 136}

abdx 136

text\footnote{footnote text}

\end{document}