Bug#929567:

[Vincent Lefevre]

On 2019-06-06 09:31:28 +0200, Andreas Henriksson wrote:
> On Wed, Jun 05, 2019 at 03:51:47PM +0000, J. Smith wrote:
> > See https://debbugs.gnu.org/30045 (fixed in Emacs 26.2).
> 
> According to the merged upstream duplicates these should be the relevant
> fixes:
> 
> http://git.savannah.gnu.org/cgit/emacs.git/commit/?h=emacs-26.2&id=408bf21a8c
> http://git.savannah.gnu.org/cgit/emacs.git/commit/?h=emacs-26.2&id=95b77b0451
> http://git.savannah.gnu.org/cgit/emacs.git/commit/?h=emacs-26.2&id=3deaac1bd9
> 
> Hoping someone can test and verify that fixes the issue....

When using the first two (the third one is a cosmetic change),
rendering the character is slow, but Emacs no longer crashes.
I've attached the resulting patch.

-- 
Vincent Lefèvre <vincent at vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)
-------------- next part --------------
Index: emacs-26.1+1/src/font.c
===================================================================
--- emacs-26.1+1.orig/src/font.c
+++ emacs-26.1+1/src/font.c
@@ -5473,6 +5473,13 @@ Disabling compaction of font caches migh
 footprint in sessions that use lots of different fonts.  */);
   inhibit_compacting_font_caches = 0;
 
+  DEFVAR_BOOL ("xft-ignore-color-fonts",
+	       Vxft_ignore_color_fonts,
+	       doc: /*
+Non-nil means don't query fontconfig for color fonts, since they often
+cause Xft crashes.  Only has an effect in Xft builds.  */);
+  Vxft_ignore_color_fonts = 1;
+
 #ifdef HAVE_WINDOW_SYSTEM
 #ifdef HAVE_FREETYPE
   syms_of_ftfont ();
Index: emacs-26.1+1/src/ftfont.c
===================================================================
--- emacs-26.1+1.orig/src/ftfont.c
+++ emacs-26.1+1/src/ftfont.c
@@ -764,6 +764,13 @@ ftfont_spec_pattern (Lisp_Object spec, c
   if (scalable >= 0
       && ! FcPatternAddBool (pattern, FC_SCALABLE, scalable ? FcTrue : FcFalse))
     goto err;
+#if defined HAVE_XFT && defined FC_COLOR
+  /* We really don't like color fonts, they cause Xft crashes.  See
+     Bug#30874.  */
+  if (Vxft_ignore_color_fonts
+      && ! FcPatternAddBool(pattern, FC_COLOR, FcFalse))
+    goto err;
+#endif
 
   goto finish;