bug#45557: 27.1; Incorrect rendering of COMBINING OVERLINE

[Eli Zaretskii]

> Date: Thu, 07 Jan 2021 11:40:31 +0530 (IST)
> Cc: 45557@debbugs.gnu.org
> From: Madhu <enometh@meer.net>
> 
> *  Eli Zaretskii <eliz@gnu.org> <83turu11xm.fsf@gnu.org>
> Wrote on Wed, 06 Jan 2021 18:10:29 +0200
> >> From: Madhu <enometh@meer.net>
> >> > Anyway, I see no Emacs problems in your description, only font
> >> > problems.  The text you sent is displayed correctly on my system, both
> >> > of its lines.
> Can you try using a font with emacs which does not compose the x and
> overbar?

I already did.  The results are as I'd expect: the characters are
rendered separately.

> >> I assume the mswindows and applemac systems dont pull in harfbuzz?
> > No, the Windows build does use HarfBuzz.
> Whatever is doing the visual composition of x + overbar (when emacs is
> explicitly asked not to do it by turning auto-composition-mode off) -
> it isn't harfbuzz.  It happens on an emacs (--without-all) which links
> to freetype without harfbuzz/cairo (and even when emacs isn't using m17n-lib)
> Very puzzling.

Indeed.