[Feature request] Option to choose if SCRIPT unicode input must be rendered with scr of cal

[pierrecagne]

Description

When using unicode-math with unicode character in the .tex source, the inputs 𝒜 to 𝒵 (MATHEMATICAL SCRIPT CAPITAL letters, although some of them like ℒ and ℬ seem to be in the Letterlike Symbols block instead) in math mode are rendered with the src style of the main math font. I suggest there is an option to the unicode-math package so that one can choose that these unicode inputs are rendered by the scr or cal style of the rest of the document selected by range.

Add info or delete as appropriate:

• Relevant for XeTeX
• Relevant for LuaTeX
• See https://tex.stackexchange.com/q/687461/29611 for a local solution (answer by David Carlisle), letter by letter, that could serve as a basis for implementing the feature.

Minimal example demonstrating the issue

The following source:

\documentclass{minimal}

\usepackage{fontspec}
\usepackage{unicode-math}

\setmathfont{Libertinus Math Regular}
\setmathfont{TeX Gyre Pagella Math}[range=cal]
\setmathfont{Latin Modern Math}[range=scr]

\begin{document}
Unicode input: $ℒ$

Mathcal input: $\mathcal L$

Mathscr input: $\mathscr L$
\end{document}

renders 3 different Ls. The first of which is the src style of Libertinus Math Regular.

A script=... option of the package would allow the user to choose how to render this first L:

\documentclass{minimal}

\usepackage{fontspec}
\usepackage[script=cal]{unicode-math}

\setmathfont{Libertinus Math Regular}
\setmathfont{TeX Gyre Pagella Math}[range=cal]
\setmathfont{Latin Modern Math}[range=scr]

\begin{document}
Unicode input: $ℒ$

Mathcal input: $\mathcal L$

Mathscr input: $\mathscr L$
\end{document}

In that case, the first L is rendered as the second one.