Re: harfbuzz 2f72162: Fix crash in the Cairo build

[Eli Zaretskii <eliz@gnu.org>]

> From: Robert Pluim <rpluim@gmail.com>
> Cc: emacs-devel@gnu.org
> Date: Fri, 08 Feb 2019 15:38:52 +0100
> 
> > That's orthogonal.  Regardless of whether we want to drop ftxfont.c, I
> > don't understand why build with both xftfont.c and ftxfont.c.  They
> > seem to be mutually exclusive, from the end-user POV.
> 
> Removing ftxfont.c from the HAVE_XFT build is the same as dropping it:
> 
> configure.ac:
> 
>     ## We used to allow building with FreeType and without Xft.
>     ## However, the ftx font backend driver is not in good shape.
>     if test "$HAVE_XFT" != "yes"; then
>        dnl For the "Does Emacs use" message at the end.
>        HAVE_XFT=no
>        HAVE_FREETYPE=no
>     else
>     
>   elif test "$HAVE_XFT" = "yes"; then
>     FONT_OBJ="$FONT_OBJ ftfont.o xftfont.o ftxfont.o"
>   elif test "$HAVE_FREETYPE" = "yes"; then
>     FONT_OBJ="$FONT_OBJ ftfont.o ftxfont.o"
>   fi
> 
> I donʼt mind either way: as you rightly point out, nobody can possibly
> be using it :-)

The above is strange, since the code which uses font backends clearly
meant something else:

  #ifdef USE_CAIRO
    register_font_driver (&ftcrfont_driver, f);
  #else
  #ifdef HAVE_FREETYPE
  #ifdef HAVE_XFT
    register_font_driver (&xftfont_driver, f);
  #else	/* not HAVE_XFT */
    register_font_driver (&ftxfont_driver, f);
  #endif	/* not HAVE_XFT */
  #endif	/* HAVE_FREETYPE */
    register_font_driver (&xfont_driver, f);
  #endif	/* not USE_CAIRO */

Here, xftfont and ftxfont are clearly 2 more-or-less equivalent
alternatives, and bot rely on Freetype.  So I don't understand why not
having XFT is taken by configure.ac to mean there's no Freetype,
either.  Sounds like a mistake, or did I miss something?

> >> >> I can cherry-pick this to the harfbuzz branch if you want.
> >> >
> >> > Thanks, please do.
> >> 
> >> Will do.
> >
> > TIA
> 
> Done as 015a6e1df2

Thanks.