bug#52888: closed (29.0.50; font_{delete_unmatched,score} do not handle nil FONT_WEIGHT_INDEX)

[GNU bug Tracking System]

Your message dated Wed, 12 Jan 2022 16:56:44 +0200
with message-id <83k0f557f7.fsf@gnu.org>
and subject line Re: bug#52888: 29.0.50; font_{delete_unmatched,score} do not 
handle nil FONT_WEIGHT_INDEX
has caused the debbugs.gnu.org bug report #52888,
regarding 29.0.50; font_{delete_unmatched,score} do not handle nil 
FONT_WEIGHT_INDEX
to be marked as done.

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-- 
52888: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=52888
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--- Begin Message --- Subject: 29.0.50; font_{delete_unmatched,score} do not handle nil FONT_WEIGHT_INDEX Date: Wed, 29 Dec 2021 22:28:37 -0700 User-agent: Notmuch/0.31.4 (https://notmuchmail.org) Emacs/29.0.50 (x86_64-pc-linux-gnu)

Hello,

On my system I have a variable weight .ttf font[1] installed somewhere.
When I build with --enable-check-lisp-object-type, the line

    int candidate = XFIXNUM (AREF (entity, prop)) >> 8;

in font_delete_unmatched and the expression

   EMACS_INT diff = ((XFIXNUM (AREF (entity, i)) >> 8)
                     - (XFIXNUM (spec_prop[i]) >> 8));

in font_score have failed assertions because the FONT_WEIGHT_INDEX for
this .ttf file is nil:

    #<font-entity ftcrhb CYRE Inconsolata nil iso10646-1 nil normal nil
     0 nil 100 0 ((:font-entity
     "/usr/share/fonts/inconsolata/Inconsolata-VariableFont_wdth,wght.ttf"
     . 0))>

I don't believe Emacs really knows how to handle these multi-weight .ttf
files?  Thus I propose the attached patch, to handle the value.

[1]  https://github.com/googlefonts/Inconsolata/tree/main/fonts/variable

-- 
Sean Whitton

0001-Handle-nil-FONT_WEIGHT_INDEX.patch
Description: Text Data

--- End Message ---

> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#52888: 29.0.50; font_{delete_unmatched,score} do not handle nil FONT_WEIGHT_INDEX
>
>
>
>
> Date: 
>
> Wed, 12 Jan 2022 16:56:44 +0200
>
>
>
>
> > From: Sean Whitton <spwhitton@spwhitton.name>
> > Cc: 52888@debbugs.gnu.org
> > Date: Thu, 06 Jan 2022 11:10:12 -0700
> > 
> > > OK, but (a) we need a comment there explaining why FC_VARIABLE is used
> > > as the condition, and (b) we'd also need to merge the temporary fix in
> > > font.c to master.
> > 
> > Here's an updated patch.  I don't think I can help with (b) but let me
> > know if there's something I can do.
>
> Thanks, I installed this, and also installed a followup change that is
> the "temporary fix" from emacs-28 adapted to the code on master.
>
> And with that, I'm closing this bug.  Thanks for working on this.
>
>
> --- End Message ---