bug#59306: 29.0.50; Resurrected bug?

[Dmitry Gutov]

On 20.11.2022 02:36, Po Lu via Bug reports for GNU Emacs, the Swiss army 
knife of text editors wrote:
> Dmitry Gutov<dgutov@yandex.ru>  writes:
>
> > No change since the last test I tried: fonts seem fine, but the frame
> > size is jumping. I even did 'make bootstrap' to be doubly sure.
> Thanks.  Could you place a breakpoint on `apply_xft_settings' before
> starting "emacs -Q", step through it, and try to find out what causes
> the `changed' variable to be set to true?

Apparently it's this part:

#ifdef FC_HINT_STYLE
  if ((settings->seen & SEEN_HINTSTYLE) != 0
      && oldsettings.hintstyle != settings->hintstyle)
    {
      FcPatternDel (pat, FC_HINT_STYLE);
      FcPatternAddInteger (pat, FC_HINT_STYLE, settings->hintstyle);
      changed = true;
      oldsettings.hintstyle = settings->hintstyle;
    }
#endif

Here's the relevant part of the gdb log, since I don't have much 
experience with it. The assignment statement itself seems to be missing 
from the stepping, but 'changed' became true after:

(gdb) n
842       FcPatternGetDouble (pat, FC_DPI, 0, &oldsettings.dpi);
(gdb) p changed
$2 = false
(gdb) n
844       if ((settings->seen & SEEN_AA) != 0 && oldsettings.aa != 
settings->aa)
(gdb) n
852       if ((settings->seen & SEEN_HINTING) != 0
(gdb) n
860       if ((settings->seen & SEEN_RGBA) != 0 && oldsettings.rgba != 
settings->rgba)
(gdb) n
869       if ((settings->seen & SEEN_LCDFILTER) != 0
(gdb) n
879       if ((settings->seen & SEEN_HINTSTYLE) != 0
(gdb) n
882           FcPatternDel (pat, FC_HINT_STYLE);
(gdb) n
883           FcPatternAddInteger (pat, FC_HINT_STYLE, settings->hintstyle);
(gdb) n
885           oldsettings.hintstyle = settings->hintstyle;
(gdb) n
894       oldsettings.dpi = dpyinfo->resx;
(gdb) p changed
$3 = true