[Bug: 21.5-b29] Syntactic font-lock confuses skip-syntax-forward

================================================================ Dear Bug Team! [The System Info section is a mock up from xemacs -vanilla, since ironically #'report-xemacs-bug combined with one of my packages throws XEmacs into an infinite loop when creating the message buffer. Wouldn't be surprising if that is related somehow to the bleeding edge version of Gnus.] * Background I am working on a language mode, which uses syntactic highlighting to locally modify the syntax-class of ?| (from ?$ to $w), so that parenthesis matching would not get confused by interleaved sexps. The below code snippet is from my actual testcase: [ {ENDIAN} == "little" SETEND LE | ; <<< local syntax-table modification SETEND BE ] * Description When parsing the buffer, I observe strange behavior once the parser gets past the point where font-lock-syntactic-keywords matches this: ("^\\s-+\\(|\\)" 1 (3 . nil)) I was able to track this down to #'skip-syntax-forward, which would return nil independent of its SYNTAX argument. Unfortunately, this error occurs sporadically (but often enough to trigger it reasonably quick) and seems to be related to moving point across the critical line where the syntax-table gets modified. After encountering the error, certain changes of point will reset the error state, so that s-s-f will start behaving normally again. It is perhaps worthwhile mentioning that on my Win32 (Windows 7) XEmacs ,---- | Microsoft Windows XP [Version 5.1.2600] | OS: Windows_NT | | XEmacs 21.5-b29 "garbanzo" configured for `i586-pc-win32'. `---- the error occurs rather frequently, while it is a lot harder (but possible) to trigger on a more recent XEmacs whose information is attached. * Wild Guess Is there a possibility of a race condition, between font-lock assigning the new syntax-class and other code accessing this? * Request I have never debugged any XEmacs code on C level. Is there a "Getting Started" document somewhere? Especially the macros seem scary. It doesn't help that running my self-compiled XEmacs under GDB (Ubuntu) will segfault in memset()... ,---- | (gdb) r | Starting program: /usr/local/bin/xemacs | [Thread debugging using libthread_db enabled] | | Program received signal SIGSEGV, Segmentation fault. | memset () at ../sysdeps/x86_64/memset.S:337 | 337 ../sysdeps/x86_64/memset.S: No such file or directory. | in ../sysdeps/x86_64/memset.S | (gdb) `---- Best regards Marcus ================================================================ System Info to help track down your bug: --------------------------------------- uname -a: Linux dipsy 2.6.35-24-generic #42-Ubuntu SMP Thu Dec 2 02:41:37 UTC 2010 x86_64 GNU/Linux ./configure '--with-pop' '--with-sound=alsa' '--enable-menubars=lucid' '--enable-scrollbars=athena' '--enable-dialogs=athena' '--enable-widgets=athena' '--with-athena=3d' '--without-gpm' '--without-ldap' '--without-postgresql' '--with-mule' '--without-xim' '--without-canna' '--with-xft=emacs,tabs,gauges,menubars' '--with-zlib' '--without-bignum' '--with-kkcc' '--with-newgc' '--without-error-checking' '--with-modules' '--with-database=berkdb' '--with-ncurses' XEmacs 21.5-b29 "garbanzo" 317ebaee6e4f configured for `x86_64-unknown-linux'. Compilation Environment and Installation Defaults: Source code location: /home/marcus/projekte/xemacs-beta-compile Installation prefix: /usr/local Not using any operating system description file Not using any machine description file Compiler version: gcc (Ubuntu/Linaro 4.4.4-14ubuntu5) 4.4.5 - GCC specs file: specs. - Compiler command: gcc -Wall -Wno-switch -Wundef -Wsign-compare -Wno-char-subscripts -Wpacked -Wshadow -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wdeclaration-after-statement -Wunused-parameter -g libc version: GNU libc 2.12.1-0ubuntu10 (Debian) Relocating allocator for buffers: no GNU version of malloc: yes - Using Doug Lea's new malloc from the GNU C Library. Window System: Compiling in support for the X window system: - X Windows headers location: - X Windows libraries location: - Handling WM_COMMAND properly. - Using fontconfig to manage fonts. - Compiling in support for Xft antialiased fonts (EXPERIMENTAL). Compiling in support for the Athena widget set: - Athena headers location: X11/Xaw3d - Athena library to link: Xaw3d Using Lucid menubars. - Using Xft to render antialiased fonts in menubars. WARNING: This Xft feature will be replaced with a face. Using Athena scrollbars. Using Athena dialog boxes. Using Athena native widgets. - Using Xft to render antialiased fonts in tab controls. WARNING: This Xft feature will be replaced with a face. - Using Xft to render antialiased fonts in progress bars. WARNING: This Xft feature will be replaced with a face. WARNING: This Xft feature not yet implemented; setting ignored. TTY: Compiling in support for ncurses. Images: Compiling in support for XPM images. Compiling in support for PNG images. Compiling in support for JPEG images. Compiling in support for TIFF images. Compiling in support for X-Face message headers. Sound: Compiling in support for sound (native). Compiling in support for ALSA (Advanced Linux Sound Architecture). Databases: Compiling in support for Berkeley database. Compiling in support for GNU DBM. Internationalization: Compiling in support for Mule (multi-lingual Emacs). Mail: Compiling in support for POP mail retrieval. Compiling in support for "file" mail spool file locking method. Other Features: Inhibiting IPv6 canonicalization at startup. Compiling in support for dynamic shared object modules. Using the new GC mark algorithms (KKCC). WARNING: --------------------------------------------------------- WARNING: The new algorithms are experimental. They are enabled by WARNING: default for this release. Use `--disable-kkcc' to WARNING: turn it off. WARNING: --------------------------------------------------------- Using the new incremental garbage collector and the new allocator. Using POSIX sigaction() to install fault handler. Using the new portable dumper. Compiling in support for extra debugging code. Load-Path Lisp Shadows: ---------------------- (/usr/local/share/xemacs/site-packages/lisp/gnus/hex-util /usr/local/share/xemacs/xemacs-packages/lisp/ecrypto/hex-util /usr/local/share/xemacs/site-packages/lisp/gnus/md4 /usr/local/share/xemacs/xemacs-packages/lisp/ecrypto/md4 /usr/local/share/xemacs/site-packages/lisp/gnus/sha1 /usr/local/share/xemacs/xemacs-packages/lisp/ecrypto/sha1 /usr/local/share/xemacs/site-packages/lisp/gnus/rfc2104 /usr/local/share/xemacs/xemacs-packages/lisp/mail-lib/rfc2104 /usr/local/share/xemacs/site-packages/lisp/gnus/netrc /usr/local/share/xemacs/xemacs-packages/lisp/mail-lib/netrc /usr/local/share/xemacs/site-packages/lisp/gnus/tls /usr/local/share/xemacs/xemacs-packages/lisp/mail-lib/tls /usr/local/share/xemacs/site-packages/lisp/gnus/starttls /usr/local/share/xemacs/xemacs-packages/lisp/mail-lib/starttls /usr/local/share/xemacs/site-packages/lisp/gnus/pop3 /usr/local/share/xemacs/xemacs-packages/lisp/mail-lib/pop3 /usr/local/share/xemacs/site-packages/lisp/gnus/dns-mode /usr/local/share/xemacs/xemacs-packages/lisp/net-utils/dns-mode /usr/local/share/xemacs/site-packages/lisp/gnus/dig /usr/local/share/xemacs/xemacs-packages/lisp/net-utils/dig /usr/local/share/xemacs/site-packages/lisp/gnus/dns /usr/local/share/xemacs/xemacs-packages/lisp/net-utils/dns /usr/local/share/xemacs/site-packages/lisp/gnus/pgg-gpg /usr/local/share/xemacs/xemacs-packages/lisp/pgg/pgg-gpg /usr/local/share/xemacs/site-packages/lisp/gnus/pgg /usr/local/share/xemacs/xemacs-packages/lisp/pgg/pgg /usr/local/share/xemacs/site-packages/lisp/gnus/pgg-parse /usr/local/share/xemacs/xemacs-packages/lisp/pgg/pgg-parse /usr/local/share/xemacs/site-packages/lisp/gnus/pgg-def /usr/local/share/xemacs/xemacs-packages/lisp/pgg/pgg-def /usr/local/share/xemacs/site-packages/lisp/gnus/pgg-pgp5 /usr/local/share/xemacs/xemacs-packages/lisp/pgg/pgg-pgp5 /usr/local/share/xemacs/site-packages/lisp/gnus/pgg-pgp /usr/local/share/xemacs/xemacs-packages/lisp/pgg/pgg-pgp /usr/local/share/xemacs/site-packages/lisp/gnus/sasl-ntlm /usr/local/share/xemacs/xemacs-packages/lisp/sasl/sasl-ntlm /usr/local/share/xemacs/site-packages/lisp/gnus/sasl-digest /usr/local/share/xemacs/xemacs-packages/lisp/sasl/sasl-digest /usr/local/share/xemacs/site-packages/lisp/gnus/hmac-md5 /usr/local/share/xemacs/xemacs-packages/lisp/sasl/hmac-md5 /usr/local/share/xemacs/site-packages/lisp/gnus/sasl-cram /usr/local/share/xemacs/xemacs-packages/lisp/sasl/sasl-cram /usr/local/share/xemacs/site-packages/lisp/gnus/sasl /usr/local/share/xemacs/xemacs-packages/lisp/sasl/sasl /usr/local/share/xemacs/site-packages/lisp/gnus/hmac-def /usr/local/share/xemacs/xemacs-packages/lisp/sasl/hmac-def /usr/local/share/xemacs/site-packages/lisp/gnus/ntlm /usr/local/share/xemacs/xemacs-packages/lisp/sasl/ntlm /usr/local/share/xemacs/mule-packages/lisp/mule-base/japan-util /usr/local/share/xemacs-21.5-b29/lisp/mule/japan-util /usr/local/share/xemacs/mule-packages/lisp/mule-base/china-util /usr/local/share/xemacs-21.5-b29/lisp/mule/china-util /usr/local/share/xemacs/mule-packages/lisp/mule-base/ethio-util /usr/local/share/xemacs-21.5-b29/lisp/mule/ethio-util /usr/local/share/xemacs/mule-packages/lisp/mule-base/korea-util /usr/local/share/xemacs-21.5-b29/lisp/mule/korea-util /usr/local/share/xemacs/mule-packages/lisp/mule-base/viet-util /usr/local/share/xemacs-21.5-b29/lisp/mule/viet-util /usr/local/share/xemacs/xemacs-packages/lisp/xemacs-base/regexp-opt /usr/local/share/xemacs-21.5-b29/lisp/regexp-opt /usr/local/share/xemacs/xemacs-packages/lisp/xemacs-base/easy-mmode /usr/local/share/xemacs-21.5-b29/lisp/easy-mmode /usr/local/share/xemacs/xemacs-packages/lisp/apel/alist /usr/local/share/xemacs-21.5-b29/lisp/alist) Internationalization Settings: ------------------------- Environment: Value of LC_ALL : nil Value of LC_COLLATE : nil Value of LC_CTYPE : nil Value of LC_MESSAGES : nil Value of LC_MONETARY : nil Value of LC_NUMERIC : nil Value of LC_TIME : nil Value of LANG : en_US.UTF-8 Lisp locale settings: current-language-environment => "English (UTF-8)" default-buffer-file-coding-system => utf-8 default-process-coding-system => (undecided . utf-8) (current-locale) => "en_US.UTF-8" keyboard-coding-system => utf-8 terminal-coding-system => utf-8 (coding-priority-list) => (utf-8 iso-8-1 utf-16-little-endian-bom utf-16-bom utf-8-bom iso-7 no-conversion iso-8-2 iso-8-designate iso-lock-shift shift-jis big5 utf-16-little-endian utf-16 ucs-4) Coding system aliases: 'native is aliased to utf-8 'file-name is aliased to utf-8 'mswindows-multibyte-system-default is not a coding system alias Installed XEmacs Packages: ------------------------- (xwem ver: 1.23 upstream: lg(a)xwem.org--2005/xwem--main--2.1--versionfix-1) (xslt-process ver: 1.12 upstream: 1.2.1) (xslide ver: 1.09 upstream: 0.2.2) (xlib ver: 1.14 upstream: lg(a)xwem.org--2005/xlib--main--2.1--version-0) (xemacs-devel ver: 1.8 upstream: 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R-2_9_9) (pc ver: 1.28 upstream: No-Upstream-Ver) (os-utils ver: 1.41 upstream: No-Upstream-Ver) (net-utils ver: 1.56 upstream: N/A) (mmm-mode ver: 1.05 upstream: 0.4.8) (misc-games ver: 1.22 upstream: No-Upstream-Ver) (mine ver: 1.16 upstream: 1.9) (mailcrypt ver: 2.14 upstream: 3.5.8) (mail-lib ver: 1.8 upstream: No-Upstream-Ver) (ilisp ver: 1.36 upstream: 5.12.0) (igrep ver: 1.16 upstream: 2.111) (idlwave ver: 1.32 upstream: 5.1) (ibuffer ver: 1.1 upstream: No-Upstream-Ver) (hm--html-menus ver: 1.24 upstream: 5.9) (gnats ver: 1.17 upstream: 3.101) (general-docs ver: 1.06 upstream: No-Upstream-Ver) (games ver: 1.2 upstream: 2.00) (fsf-compat ver: 1.19 upstream: No-Upstream-Ver) (footnote ver: 1.16 upstream: 0.18x) (eudc ver: 1.4 upstream: 1.32) (eterm ver: 1.18 upstream: No-Upstream-Ver) (eshell ver: 1.18 upstream: 0fc80a3f6bb3bb59f42e9ff83cc8b89bf90fe658) (elib ver: 1.13 upstream: 1.0) (efs ver: 1.34 upstream: 1.24) (edit-utils ver: 2.43 upstream: No-Upstream-Ver) (ediff ver: 1.81 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texinfo-autoloads supercite-autoloads strokes-autoloads sounds-wav-autoloads sounds-au-autoloads slider-autoloads sh-script-autoloads sasl-autoloads rmail-autoloads reftex-autoloads re-builder-autoloads python-modes-autoloads psgml-autoloads ps-print-autoloads prog-modes-autoloads pgg-autoloads perl-modes-autoloads pcomplete-autoloads pcl-cvs-autoloads pc-autoloads os-utils-autoloads net-utils-autoloads mmm-mode-autoloads misc-games-autoloads mine-autoloads mailcrypt-autoloads mail-lib-autoloads ilisp-autoloads igrep-autoloads idlwave-autoloads ibuffer-autoloads hm--html-menus-autoloads gnats-autoloads general-docs-autoloads games-autoloads fsf-compat-autoloads footnote-autoloads eudc-autoloads eterm-autoloads eshell-autoloads elib-autoloads efs-autoloads edit-utils-autoloads ediff-autoloads edebug-autoloads ecrypto-autoloads ecb-autoloads docbookide-autoloads dired-autoloads debug-autoloads cookie-autoloads cc-mode-autoloads calendar-autoloads calc-autoloads c-support-autoloads 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