Re: Can watermarking Unicode text using invisible differences sneak through Emacs, or can Emacs detect it?

[Eli Zaretskii]

> From: Richard Stallman <rms@gnu.org>
> Cc: psainty@orcon.net.nz, luangruo@yahoo.com, emacs-devel@gnu.org
> Date: Fri, 21 Jan 2022 23:37:59 -0500
> 
> I'm asking about a feature whereby a user can direct Emacs not to use
> ligatures in display on a certain terminal.  The idea is, when using a
> terminal that can't display ligatures, Emacs should always display
> multiple letters instead of a ligature.

We don't have a way of determining whether a terminal can display
ligatures.  Increasingly, terminal emulators acquire these
capabilities, and we have already a couple that display ligatures and
Emoji sequences.  But there are no methods known to us to query the
terminal whether such support exists and/or which ligatures are
supported.

The user can disable auto-composition-mode or customize
composition-function-table to disable some or all of the text-shaping
features.

> I doubt any user wants to see a diamond instead of `fi'.

Is this what really happens for you, on your terminal?