bug#45184: 26.1; Private Unicode plains 15 and 16 seem not supported

[Eli Zaretskii <eliz@gnu.org>]

> From: jsbien@mimuw.edu.pl (Janusz S. Bień)
> Cc: 45184@debbugs.gnu.org
> Date: Sat, 12 Dec 2020 11:29:07 +0100
> 
> > Also, please describe in detail how you selected the font in question.
> > I don't think you told that in your original report.
> 
> I didn't told because I expected the font to be found automatically.
> 
> In an additional experiment I just used `S-down-mouse-1’ and selected
> the font from the list.

And what happens then? are any characters displayed correctly, or all
of them are displayed as hex codes?

> Please note that vim (installed especially for testing) finds the font
> automatically and displays the characters correctly.

I don't know how vim selects the fonts, but I'm sure it's very
different from what Emacs does.  We need to understand what prevents
Emacs from using this font as you expected.

Anyway, I think it's time to present more details, if you please:

  . does this happen in "emacs -Q"?
  . did you customize your fontsets, and if so, can you show those
    customizations?
  . which codepoints are used for the problematic characters, and
    which characters are those? do they have codepoints in Unicode?
  . can you make the font in question available for download, so we
    could try debugging this in Emacs?
  . assuming the font is installed, can you show a minimal recipe for
    reproducing the problem in "emacs -Q"?

TIA