From 518c4881875ff7493ce8ff336ef15c1dc7994618 Mon Sep 17 00:00:00 2001
From: Kenichi Handa <handa@m17n.org>
Date: Wed, 29 Apr 2009 01:40:57 +0000
Subject: [PATCH] (x_set_font): When ARG is a font-object, check if the
 font-object matches with the ASCII font-spec of the frame's fontset.  If not,
 create a new fontset for the frame.

---
 src/frame.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/frame.c b/src/frame.c
index 80a691e35fd..eb9088b5478 100644
--- a/src/frame.c
+++ b/src/frame.c
@@ -3418,6 +3418,16 @@ x_set_font (f, arg, oldval)
 	 itself in the future.  */
       arg = AREF (font_object, FONT_NAME_INDEX);
       fontset = FRAME_FONTSET (f);
+      /* Check if we can use the current fontset.  If not, set FONTSET
+	 to -1 to generate a new fontset from FONT-OBJECT.  */
+      if (fontset >= 0)
+	{
+	  Lisp_Object ascii_font = fontset_ascii (fontset);
+	  Lisp_Object spec = font_spec_from_name (ascii_font);
+
+	  if (! font_match_p (spec, font_object))
+	    fontset = -1;
+	}
     }
   else
     signal_error ("Invalid font", arg);
-- 
2.39.2