bug#4714: 23.1.50; wrong-type-argument stringp nil in gdb

bug#4714: 23.1.50; wrong-type-argument stringp nil in gdb

[Robert Marshall]

Please write in English if possible, because the Emacs maintainers
usually do not have translators to read other languages for them.

Your bug report will be posted to the emacs-pretest-bug@gnu.org mailing list.

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

If you download the program
http://clivecooper.co.uk/tutorial/changetime.tar.gz
from
http://clivecooper.co.uk/tutorial/index.html

(this was just used to get a small enough program which replicated the
bug - I'm guessing there may be a issue with qt moc'ed file here)

the tar file includes a compiled version of the program - but you should
probably build it yourself though you'll need a qt dev environment.

Run the program under gdb and when the program window appears interrupt
it in gdb and once interrupted move one level up the call stack.

You then get a wrong-type-argument stringp nil error:

Debugger entered--Lisp error: (wrong-type-argument stringp nil)
  string-match("//+" nil)
  gud-find-file(nil)
  gud-display-line(nil 83)
  gud-display-frame()
  gdb-frame-handler()


If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
    `bt full' and `xbacktrace'.
If you would like to further debug the crash, please read the file
/home/robert/emacs/etc/DEBUG for instructions.


In GNU Emacs 23.1.50.4 (x86_64-unknown-linux-gnu, GTK+ Version 2.16.1)
 of 2009-10-13 on robert-laptop
Windowing system distributor `The X.Org Foundation', version 11.0.10600000
Important settings:
  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_GB.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: Emacs-Lisp

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


Recent messages:
This version of GDB doesn't support non-stop mode.  Turning it off.
Command: up 1
error in process filter: gud-find-file: Wrong type argument: stringp, nil
error in process filter: Wrong type argument: stringp, nil
Mark set

Load-path shadows:
None found.

Features:
(shadow mail-extr message ecomplete rfc822 mml mml-sec password-cache
mm-decode mm-bodies mm-encode mailcap mail-parse rfc2231 rfc2047 rfc2045
qp ietf-drums mailabbrev nnheader gnus-util netrc time-date mm-util
mail-prsvr gmm-utils wid-edit mailheader canlock sha1 hex-util hashcash
mail-utils emacsbug sendmail help-mode view debug gdb-mi bindat json gud
easy-mmode comint ring multi-isearch parse-time vc-cvs cc-mode cc-fonts
easymenu cc-menus cc-cmds cc-styles cc-align cc-engine cc-vars cc-defs
dired regexp-opt tooltip ediff-hook vc-hooks lisp-float-type mwheel
x-win x-dnd tool-bar dnd fontset image fringe lisp-mode register page
menu-bar rfn-eshadow timer select scroll-bar mldrag mouse jit-lock
font-lock syntax facemenu font-core frame cham georgian utf-8-lang
misc-lang vietnamese tibetan thai tai-viet lao korean japanese hebrew
greek romanian slovak czech european ethiopic indian cyrillic chinese
case-table epa-hook jka-cmpr-hook help simple abbrev loaddefs button
minibuffer faces cus-face text-properties overlay md5 base64 format env
code-pages mule custom widget hashtable-print-readable backquote
make-network-process gtk x-toolkit x multi-tty emacs)

-- 
Robert A J Marshall,  
TNEI Services Ltd, 86-90 London Road, Manchester, M1 2PW 
web: http://IPSA-Power.com 

bug#4714: 23.1.50; wrong-type-argument stringp nil in gdb

[Chong Yidong]

> Debugger entered--Lisp error: (wrong-type-argument stringp nil)
>   string-match("//+" nil)
>   gud-find-file(nil)
>   gud-display-line(nil 83)
>   gud-display-frame()
>   gdb-frame-handler()

Sorry for the long delay in replying.  I think this was a bug in the
`gdb-source' function of gdb-ui.el, which should be fixed with the
following patch.  But gdb-ui.el has since been replaced with a different
implementation, gdb-mi.el, in the trunk, which does not have this
problem.

*** lisp/progmodes/gdb-ui.el	2011-01-02 23:50:46 +0000
--- lisp/progmodes/gdb-ui.el	2011-12-26 08:15:50 +0000
***************
*** 1427,1442 ****
  
  ;; Do not use this except as an annotation handler.
  (defun gdb-source (args)
!   (string-match gdb-source-spec-regexp args)
!   ;; Extract the frame position from the marker.
!   (setq gud-last-frame
! 	(cons
! 	 (match-string 1 args)
! 	 (string-to-number (match-string 2 args))))
!   (setq gdb-pc-address (match-string 3 args))
!   ;; cover for auto-display output which comes *before*
!   ;; stopped annotation
!   (if (eq gdb-output-sink 'inferior) (setq gdb-output-sink 'user)))
  
  (defun gdb-pre-prompt (ignored)
    "An annotation handler for `pre-prompt'.
--- 1427,1442 ----
  
  ;; Do not use this except as an annotation handler.
  (defun gdb-source (args)
!   (when (string-match gdb-source-spec-regexp args)
!     ;; Extract the frame position from the marker.
!     (setq gud-last-frame
! 	  (cons
! 	   (match-string 1 args)
! 	   (string-to-number (match-string 2 args))))
!     (setq gdb-pc-address (match-string 3 args))
!     ;; cover for auto-display output which comes *before*
!     ;; stopped annotation
!     (if (eq gdb-output-sink 'inferior) (setq gdb-output-sink 'user))))
  
  (defun gdb-pre-prompt (ignored)
    "An annotation handler for `pre-prompt'.