GNU bug report logs - #40864
27.0.91; Infinite loop in composing ligatures in overlays

Previous Next

Package: emacs;

Reported by: Gerry Agbobada <gagbobada <at> gmail.com>

Date: Sun, 26 Apr 2020 09:50:02 UTC

Severity: normal

Found in version 27.0.91

Fixed in version 28.1

Done: Lars Ingebrigtsen <larsi <at> gnus.org>

Bug is archived. No further changes may be made.

To add a comment to this bug, you must first unarchive it, by sending
a message to control AT debbugs.gnu.org, with unarchive 40864 in the body.
You can then email your comments to 40864 AT debbugs.gnu.org in the normal way.

Toggle the display of automated, internal messages from the tracker.

View this report as an mbox folder, status mbox, maintainer mbox


Report forwarded to bug-gnu-emacs <at> gnu.org:
bug#40864; Package emacs. (Sun, 26 Apr 2020 09:50:02 GMT) Full text and rfc822 format available.

Acknowledgement sent to Gerry Agbobada <gagbobada <at> gmail.com>:
New bug report received and forwarded. Copy sent to bug-gnu-emacs <at> gnu.org. (Sun, 26 Apr 2020 09:50:02 GMT) Full text and rfc822 format available.

Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Gerry Agbobada <gagbobada <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 27.0.91; Infinite loop in composing ligatures in overlays
Date: Sun, 26 Apr 2020 11:43:11 +0200
First : an investigation around this bug has been led in emacs-devel,
and it turns out commit fe903c5ab7354 on master branch fixes it. I am
reporting the bug for other emacs 27 users who might find this while
looking for a solution.

It is currently impossible to have an overlay with ligatures when trying
to have proper ligatures in `composition-function-table' :
;;; ligature-bug-light.el --- Reproduce an autocomposition bug -*-
lexical-binding: t; -*-
;;; Commentary:
;;
;; Reproducer for the composition table bug
;;
;;;; Method
;;
;; Evaluate the file line by line
;; Expected : "=> testing overlays" is displayed at some point and disappear
;; Actual : evaluting the 'after-string overlay-put triggers infinite
;; looping, trying to "shape unibyte text",
;; which happens to be an empty string (from my earlier debugging)
;;
;;; Code:

(defvar ligature-font-with-big-arrow "Fira Code 11"
"A valid font name for `set-frame-font'. A font with a => ligature is
necessary to trigger the bug.")
(defvar bugged-overlay nil "Bugged overlay trying to compose an empty string.")

;;;; Setup
;; Requiring composite
(require 'composite)

;; Shaping => into a ligature
(set-char-table-range composition-function-table ?= '(["=>" 0
font-shape-gstring]))

;; Setting the font
;; =>
;; At this line
(set-frame-font ligature-font-with-big-arrow nil t)
;; Now you should see ligatures for =>
;; =>

;;;; Enabling the bug
(setq bugged-overlay (make-overlay (point-at-bol 4) (point-at-eol 4)
(current-buffer)))
(overlay-put bugged-overlay 'category 'test-overlays)
;; C-x C-e at the end of this sexp will trigger infinite composition
(overlay-put bugged-overlay 'after-string "=> testing overlays")

(delete-overlay bugged-overlay) ;; cleanup in case you have a working version

(provide 'ligature-bug-light)
;;; ligature-bug-light.el ends here

In GNU Emacs 27.0.91 (build 3, x86_64-pc-linux-gnu, GTK+ Version 3.22.30)
of 2020-04-26 built on LPPS0066
Repository revision: 68f4a740a13ee6a1d98079ef655dd42924d24d41
Repository branch: emacs-27
Windowing system distributor 'The X.Org Foundation', version 11.0.11906000
System Description: Ubuntu 18.04.4 LTS

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
ligature-bug-light.el has auto save data; consider M-x recover-this-file

Configured using:
'configure --with-libzstd-from-internet --with-libb2-from-internet'

Configured features:
XPM JPEG TIFF GIF PNG SOUND DBUS GSETTINGS GLIB NOTIFY INOTIFY GNUTLS
LIBXML2 FREETYPE HARFBUZZ XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM
MODULES THREADS JSON PDUMPER GMP

Important settings:
value of $LC_MONETARY: fr_FR.UTF-8
value of $LC_NUMERIC: fr_FR.UTF-8
value of $LC_TIME: fr_FR.UTF-8
value of $LANG: en_US.UTF-8
locale-coding-system: utf-8-unix

Major mode: Emacs-Lisp

Minor modes in effect:
tooltip-mode: t
global-eldoc-mode: t
eldoc-mode: t
electric-indent-mode: t
mouse-wheel-mode: t
menu-bar-mode: t
file-name-shadow-mode: t
global-font-lock-mode: t
font-lock-mode: t
blink-cursor-mode: t
auto-composition-mode: t
auto-encryption-mode: t
auto-compression-mode: t
line-number-mode: t
transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
format-spec rfc822 mml easymenu mml-sec password-cache epa derived epg
epg-config gnus-util rmail rmail-loaddefs text-property-search time-date
subr-x seq byte-opt gv bytecomp byte-compile cconv mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader cl-loaddefs
cl-lib sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils
tooltip eldoc electric uniquify ediff-hook vc-hooks lisp-float-type
mwheel term/x-win x-win term/common-win x-dnd tool-bar dnd fontset image
regexp-opt fringe tabulated-list replace newcomment text-mode elisp-mode
lisp-mode prog-mode register page tab-bar menu-bar rfn-eshadow isearch
timer select scroll-bar mouse jit-lock font-lock syntax facemenu
font-core term/tty-colors frame minibuffer cl-generic cham georgian
utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean
japanese eucjp-ms cp51932 hebrew greek romanian slovak czech european
ethiopic indian cyrillic chinese composite charscript charprop
case-table epa-hook jka-cmpr-hook help simple abbrev obarray
cl-preloaded nadvice loaddefs button faces cus-face macroexp files
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget hashtable-print-readable backquote threads dbusbind
inotify dynamic-setting system-font-setting font-render-setting
move-toolbar gtk x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 44895 10652)
(symbols 48 6006 1)
(strings 32 15487 1594)
(string-bytes 1 507021)
(vectors 16 10026)
(vector-slots 8 130535 10300)
(floats 8 23 69)
(intervals 56 294 0)
(buffers 1000 13))




Information forwarded to bug-gnu-emacs <at> gnu.org:
bug#40864; Package emacs. (Thu, 22 Oct 2020 14:30:02 GMT) Full text and rfc822 format available.

Message #8 received at 40864 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Gerry Agbobada <gagbobada <at> gmail.com>
Cc: 40864 <at> debbugs.gnu.org
Subject: Re: bug#40864: 27.0.91; Infinite loop in composing ligatures in
 overlays
Date: Thu, 22 Oct 2020 16:29:17 +0200
Gerry Agbobada <gagbobada <at> gmail.com> writes:

> First : an investigation around this bug has been led in emacs-devel,
> and it turns out commit fe903c5ab7354 on master branch fixes it. I am
> reporting the bug for other emacs 27 users who might find this while
> looking for a solution.

OK; closing the bug report, then.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no




bug marked as fixed in version 28.1, send any further explanations to 40864 <at> debbugs.gnu.org and Gerry Agbobada <gagbobada <at> gmail.com> Request was from Lars Ingebrigtsen <larsi <at> gnus.org> to control <at> debbugs.gnu.org. (Thu, 22 Oct 2020 14:30:03 GMT) Full text and rfc822 format available.

bug archived. Request was from Debbugs Internal Request <help-debbugs <at> gnu.org> to internal_control <at> debbugs.gnu.org. (Fri, 20 Nov 2020 12:24:09 GMT) Full text and rfc822 format available.

This bug report was last modified 3 years and 129 days ago.

Previous Next


GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.