bug#27270: display-raw-bytes-as-hex generates ambiguous output for Emacs strings

[Eli Zaretskii <eliz@gnu.org>]

> Cc: npostavs@users.sourceforge.net, 27270@debbugs.gnu.org,
>  v.schneidermann@gmail.com
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Thu, 8 Jun 2017 12:43:38 -0700
> 
> On 06/08/2017 11:59 AM, Eli Zaretskii wrote:
> > That's a different issue. You said "\x905" was wrong visually, so I
> > asked how is that different, visually, from "\2205".
> 
> It's wrong visually, because I know the syntax for strings in Emacs 
> Lisp, and I know that "\x905" is supposed to be a 1-character string 
> whereas "\2205" is a two-character string.

How do you know "\2205" is a two character string?

What about this:

  (aset printable-chars #x3fffc nil) C-j
  (format "%c%c" #x3fffc ?5) C-j

Where does the octal codepoint end now?

> > Same thing happens when you copy/paste from an Emacs window which uses
> > a display table
> 
> The difference is that I don't use display tables and don't want to use 
> them. In contrast, I would like to use hexadecimal display, if it worked 
> as well as octal does (which it does not).

Then we need to code a separate feature in the Lisp reader, I think.