bug#57066: 29.0.50; Complex emoji overlaps with text

[YAMAMOTO Mitsuharu]

On Thu, 11 Aug 2022 16:43:53 +0900,
Eli Zaretskii wrote:
> 
> > Date: Thu, 11 Aug 2022 16:23:47 +0900
> > From: YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp>
> > Cc:         info@protesilaos.com,
> >     57066@debbugs.gnu.org
> > 
> > On Thu, 11 Aug 2022 15:49:10 +0900,
> > Eli Zaretskii wrote:
> > > 
> > > Do other font backends that use HarfBuzz need something similar, or is
> > > this specific to the ftcrhb backend?
> > 
> > The xfthb font backend driver does not need the similar change since
> > it always uses 1.0 / (1 << 6) as the position unit, just like the
> > patched ftcrhb code for HarfBuzz 5 and later.
> > 
> > I'm not familiar with the harfbuzz driver on W32.  But at least, the
> > bug#489 on HarfBuzz is about hb-ft.cc.  So probably the
> > uniscribe-specific part is not affected.
> 
> OK, thanks.
> 
> I think the fix should be installed on the emacs-28 release branch.
> It seems to be quite safe.  Do you agree?

Yes.  The function hb_version_atleast was introduced in HarfBuzz
version 0.9.30, and Emacs already requires 0.9.42 on non-W32 systems.

                                     YAMAMOTO Mitsuharu
                                mituharu@math.s.chiba-u.ac.jp