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

[Kévin Le Gouguec]

Eli Zaretskii <eliz@gnu.org> writes:

>>   > > I doubt any user wants to see a diamond instead of `fi'.
>> 
>>   > Is this what really happens for you, on your terminal?
>> 
>> Yes.  A few days ago I put point on a diamond, typed C-u C-x =,
>> and was told it was a ligature for `fi'.
>
> How did that ligature get written to the screen?  Was it present
> literally in some text that Emacs displayed?  If not, how did it come
> into existence, in the form of a diamond?  Emacs doesn't produce such
> ligatures on TTY frames.

(Apologies for the noise, but I thought it might be worth checking since
even after re-reading Richard's messages I'm not 100% sure every one is
talking about the same thing.

Richard, would you happen to be talking about literal U+FB01 or U+FB03
characters (fi or ffi, respectively, named "LATIN SMALL LIGATURE FI/FFI"),
rather than the kind of ligature Emacs produces when configured to do so
with "fi" and "ffi"?

I don't know much about how ligatures are setup in Emacs, but I too am
surprised that it would attempt to produce them in a terminal frame.
OTOH the aforementioned Unicode characters are indeed displayed as
diamonds on my TTY.

Again, sorry for the noise if we are indeed talking about bona-fide
ligatures)