Kashida option incompatible with Ligatures=Rare (+dlig)

[vafakhalighi]

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Brief outline of the issue

Through a lot of trial and error, I seem to have found out that settextfont does not pass Ligatures=Rare (or RawFeature=+dlig) to fontspec when package class option Kashida is used.

Is this a bug or a feature ?

Upon further inspection, the issue is not related to package option Kashida per se, but with Kashida activation within text which disables ligatures as a side effect.

In the latter case, then the documentation should specify that using Kashida excludes using discretionary ligatures.

Check/indicate

• Relevant to the bidi package
• The bidi package issue tracker has been searched for similar issues?
• Issue tracker has been searched for similar issues?
• Links to <tex.stackexchange.com> discussion if appropriate
• Links to <qa.parsilatex.com> discussion if appropriate

Minimal example showing the issue

%%!TEX TS-program = xelatex
%!TEX encoding = UTF-8 Unicode
\documentclass[12pt,a4paper]{article}
\usepackage{polyglossia}
\setdefaultlanguage{persian}
\usepackage[Kashida]{xepersian}
\settextfont{Noto Sans Arabic}[Ligatures=Rare]
\begin{document}
\begin{latin}
With KashidaOn:
\end{latin}

\KashidaOn
فرج‌الله نیک‌نژاد.


\begin{latin}
With KashidaOff:
\end{latin}

\KashidaOff
فرج‌الله نیک‌نژاد.
\end{document}

Note: The source code does not contain the kasra that is shown on Github site (where ligatures are activated !!).

Same issue appears with other fonts such as Adobe Arabic.

Expected behavior

Log and PDF files