Subject: bug#42603: EWW shows chars > #xFF with font set by "set-fontset-font"

From: Sebastian Urban <[email-masked]>
Date: Fri, 31 Jul 2020 14:01:49 +0200

>> 2. M-: (set-fontset-font t 'unicode "Times New Roman")
>
> This setting makes no sense: no single font can cover all of Unicode,
> so you should never do that.
>
> Why did you think you needed to do it in your case?

My use case is not related to EWW, but to fonts overall.  I use it to
"prevent" Emacs from searching for fonts, and to display codes of
characters instead of glyphs, to speed up loading text in situations
like in case of view-hello-file.  Then I have a file with Noto Fonts
set according to the script, like this:
    (add-to-list 'default-frame-alist '(font . "Consolas-13"))
    (set-fontset-font "fontset-default" 'unicode "Consolas")
    (set-fontset-font "fontset-default" 'unicode "Symbola" nil 'append)
    (load "noto-fonts.elc")

In this case, I simply spotted this strange behaviour of showing some
chars in my default font (Consolas) instead of variable-pitch (in my
case it's Arial), like "ł", "ą" and "ę" in sentence (see link in my
first message):
Słownik SJP.PL do programów sprawdzających pisownię (...):

When I type C-u C-x = on any of above letters, it says:
    There are text properties here:
      face                 variable-pitch
and the variable-pitch says Arial, but it's not Arial.

>> 3. Watch as some chars change font.
>>
>> The thing is, both unchanged and changed chars have face of
>> variable-pitch ("C-u C-x =" on char), so nothing should change,
>> I think.
>
> I don't think I agree.  Times New Roman doesn't support all of the
> characters.
>
> And in addition, you seem to assume that set-fontset-font overrides
> the frame's default font for the first 256 characters, which isn't
> true, AFAIK.

I think, I'm not assuming that, which I noted:
"1. Open website in EWW with chars above #xFF, e.g.:".
                                    ^^^^^^^^^^

Also, if I understood correctly your interpretation of my message:
I DON'T want to change whole text to TNR, or any other font, with this
command, quite the opposite, I don't want IT to change chars above
256, in EWW buffer that uses variable-pitch font, which is Arial.

S. U.