Re: Display of undisplayable characters: \U01F3A8 instead of diamond

[Alan Mackenzie <acm@muc.de>]

Hello, Richard.

On Thu, Aug 25, 2022 at 23:33:57 -0400, Richard Stallman wrote:
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> [[[ whether defending the US Constitution against all enemies,     ]]]
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> The text-based Linux console is unable to display many Unicode
> characters.  In Emacs 29, display of undisplayable characters has
> changed.  It used to show them with a diamond.  Now it shows the
> unicode character code as hex, preceded by \U.

Yes.  On my character bitmap, I see a reversed `?'.  I'm pretty sure
this is \Ufffd, and that your diamond is the same character.

> I find that change quite inconvenient.  It makes the text harder to
> read.  Showing the codes does no good, since I don't know these codes,
> not even for characters I am familiar with.  To find out what
> character a code represents, I have to use C-u C-x =, just as I did
> before.

As somebody who uses solely the Linux console for Emacs (apart,
sometimes, from when testing), I agree.

It disturbs me most whilst reading info.  Modern versions of makeinfo
generate Unicode punctuation characters, and having them displayed on
the screen as \Uxxxx completely screws up the alignment these characters
are meant to achieve (for example).

> I last built the sources in May.  Has this changed in a significant
> way since then?

My feeling is that the change is older than three months.  It's one of
these changes that one gradually becomes aware of, and which irritates,
but isn't quite serious enough to do anything about.  :-(

> I could not find, in NEWS, anything about this change -- it ought to
> be in NEWS .  Nor a way to go back to the old
> behavior.  Is there a way?  If not, would people please create a way?

> As a separate question, do users generally like this change?
> Would it be better to return to the old diamond method as the default?

If there were an option to use \Ufffd, I would surely set that option
that way.  Particularly in Info mode.

> -- 
> Dr Richard Stallman (https://stallman.org)
> Chief GNUisance of the GNU Project (https://gnu.org)
> Founder, Free Software Foundation (https://fsf.org)
> Internet Hall-of-Famer (https://internethalloffame.org)

-- 
Alan Mackenzie (Nuremberg, Germany).