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bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' fro
From: |
Robert Pluim |
Subject: |
bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1' |
Date: |
Fri, 04 Sep 2020 15:05:52 +0200 |
>>>>> On Fri, 04 Sep 2020 15:22:58 +0300, Eli Zaretskii <eliz@gnu.org> said:
Eli> I don't think this would help, because most scripts don't specify
Eli> language properties like 'ja' or 'ko', which is what
Eli> xfont_supported_scripts uses.
ok
>> Perhaps we should flip the default of scalable-fonts-allowed to nil
>> under GNU/Linux? [1]
>> (unless the only available font-backend is 'x', which can only happen
>> if the user explicitly sets it that way)?
Eli> That'd be backward-incompatible. Besides, I think it's too late. I
Eli> think we should do this in font.c, where the 'list' method of each
Eli> font backend is called. There, we should not call the 'x' backend
Eli> unless the no fonts were found by the backend called before it. This
Eli> should be controlled by a variable exposed to Lisp, of course.
Eli> Does that make sense?
Yes. Something like the following works, and makes displaying
etc/HELLO quite a bit faster.
diff --git a/src/font.c b/src/font.c
index 2786a772dc..6bff3a7362 100644
--- a/src/font.c
+++ b/src/font.c
@@ -2810,7 +2810,13 @@ font_list_entities (struct frame *f, Lisp_Object spec)
|| ! NILP (Vface_ignored_fonts)))
val = font_delete_unmatched (val, need_filtering ? spec : Qnil, size);
if (ASIZE (val) > 0)
- list = Fcons (val, list);
+ {
+ list = Fcons (val, list);
+ /* Querying further backends can be very slow, so we only do
+ it if the user has explicitly requested it (Bug#43177). */
+ if (query_all_font_backends == false)
+ break;
+ }
}
list = Fnreverse (list);
@@ -5527,6 +5533,13 @@ syms_of_font (void)
cause Xft crashes. Only has an effect in Xft builds. */);
xft_ignore_color_fonts = true;
+ DEFVAR_BOOL ("query-all-font-backends", query_all_font_backends,
+ doc: /*
+Non-nil means attempt to query all available font backends when
+looking up a font, otherwise stop as soon as a suitable font has been
+found. */);
+ query_all_font_backends = false;
+
#ifdef HAVE_WINDOW_SYSTEM
#ifdef HAVE_FREETYPE
syms_of_ftfont ();
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', (continued)
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Andreas Schwab, 2020/09/03
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Robert Pluim, 2020/09/03
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Alexander Shukaev, 2020/09/03
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Alexander Shukaev, 2020/09/03
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Eli Zaretskii, 2020/09/04
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Eli Zaretskii, 2020/09/03
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Andreas Schwab, 2020/09/03
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Eli Zaretskii, 2020/09/03
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Robert Pluim, 2020/09/04
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Eli Zaretskii, 2020/09/04
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1',
Robert Pluim <=
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Eli Zaretskii, 2020/09/04
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Robert Pluim, 2020/09/04
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Eli Zaretskii, 2020/09/04
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Robert Pluim, 2020/09/07
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Pip Cet, 2020/09/07
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Robert Pluim, 2020/09/07
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Eli Zaretskii, 2020/09/07
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Robert Pluim, 2020/09/07
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Robert Pluim, 2020/09/15
- bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1', Robert Pluim, 2020/09/03