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address@hidden: Emacs 21.2 -- debugger-frame-offset is 8, should be 6]
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From: |
Richard Stallman |
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Subject: |
address@hidden: Emacs 21.2 -- debugger-frame-offset is 8, should be 6] |
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Date: |
Wed, 06 Feb 2008 14:20:12 -0500 |
[I sent this message a week ago but did not get a response.]
Would someone please DTRT, then ack?
------- Start of forwarded message -------
Date: Tue, 29 Jan 2008 14:35:01 -0800
From: Derek Peschel <address@hidden>
To: address@hidden
Message-ID: <address@hidden>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
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Subject: Emacs 21.2 -- debugger-frame-offset is 8, should be 6
The debugger (not edebug, the one in debug.el) uses the
debugger-frame-offset constant to affect breakpoints on stack frames.
So if the constant becomes wrong, breakpoint commands will appear to work
but actually affect the wrong frame. I have included a patch. I don't
think the problem (and the change) depend on or affect any other parts
of Emacs, but I haven't checked.
The guidelines on bug reporting basically don't trust users to analyze
problems, so I have also included steps you can follow to see if you
agree with me. As a side effect they add a new function and keystroke
to debug.el, so that Emacs can help find the correct value of
debugger-frame-offset in the future. This is much easier than having
to go into gdb (I know, I did that), and I suggest keeping the function
in debug.el even if it's not bound to any keys.
Please let me know if you have any questions.
- -- Derek
My system:
- ----------
I'm running Mac OS 10.3.7 -- uname -a gives
Darwin Derek-Peschels-Computer.local 7.7.0 Darwin Kernel Version 7.7.0: Sun Nov
7 16:06:51 PST 2004; root:xnu/xnu-517.9.5.obj~1/RELEASE_PPC Power Macintosh
powerpc
My Emacs is the one Apple shipped -- M-x emacs-version gives
GNU Emacs 21.2.1 (powerpc-apple-darwin7.0) of 1976-04-01 on localhost
The shell commands below use bash -- echo $BASH_VERSION gives
2.05b.0(1)-release
The shell commands also use patch -- patch -v starts with
patch 2.5.8
Copyright (C) 1988 Larry Wall
Copyright (C) 2002 Free Software Foundation, Inc.
Notations:
- ----------
?> refers to a step I haven't written commands for
shell> refers to a command typed at the bash prompt.
emacs> refers to keys typed in Emacs.
emacs= followed by a space and a line of text shows the message line
(which could be a prompt for an argument, or the result of a command).
emacs= followed by dashes, a screen of text, and dashes shows the contents
of a buffer.
Included files:
- ---------------
debug.el.patch-fix patch to apply fix -- not used
in the procedure
debug.el.patch-test-orig patch to add information command
debug.el.patch-test-fix patch to add information command
and apply fix
debugger-frame-offset-test.el LISP code to set up debugger
for tests described in this procedure
Created or changed files:
- -------------------------
working directory created below (or may already exist)
debug.el.patch-test-orig copied from mail
debug.el.patch-test-fix copied from mail
debugger-frame-offset-test.el copied from mail
debug.el created below
debug.elc created below
debug.el.old created below
debug.el.new created below
debug.el.disabled-during-bug-fix temporary name for existing debug.el
debug.elc.disabled-during-bug-fix temporary name for existing debug.elc
home directory
.emacs created below
.emacs.disabled-during-bug-fix temporary name for existing .emacs
Procedure -- Setup:
- -------------------
1. start a new shell since current directory and some environment variables
will be changed
?>
2. create working directory, then change to it
shell> export WORK=~/share/emacs/site-lisp could be any directory
since it will be added
to Emacs's load-path later
shell> mkdir -p $WORK create it if needed
shell> cd $WORK
3. put debug.el.patch-test-orig and debug.el.patch-test-fix and
debugger-frame-offset-test.el in working directory
?>
4. create versions of debug.el used by later steps
shell> mv -i debug.el debug.el.disabled-during-bug-fix
if debug.el exists
shell> mv -i debug.elc debug.elc.disabled-during-bug-fix
if debug.elc exists
shell> cp /usr/share/emacs/21.2/lisp/emacs-lisp/debug.el .
or from another appropriate
directory
shell> cp -i debug.el debug.el.new
shell> patch <debug.el.patch-test-orig patches debug.el
shell> patch <debug.el.patch-test-fix patches debug.el.new
5. create working .emacs
shell> mv -i ~/.emacs ~/.emacs.disabled-during-bug-fix
if .emacs exists
shell> emacs ~/.emacs
emacs> (add-to-list 'load-path "~/share/emacs/site-lisp") RET
string in quotes must match
WORK
emacs> C-x C-c
6. byte-compile debug.el (it must run byte-compiled)
shell> emacs
emacs> M-x byte-compile-file RET
emacs= Byte compile file: ~/share/emacs/site-lisp/
prompt matches WORK
emacs> debug.el RET I get warnings about
unread-command-char being
obsolete; the debugger saves
and restores it, probably so
you can debug old code
emacs> C-x C-c
Procedure -- Show existing bug:
- -------------------------------
7. load test case, run test case
shell> emacs
emacs> M-x load-file RET
emacs= Load file: ~/share/emacs/site-lisp/
emacs> debugger-frame-offset-test.el RET
emacs=
- ------------------------------------------------------------------------------
Debugger entered: ("in fun8")
fun8()
fun7()
fun6()
fun5()
fun4()
fun3()
fun2()
fun1()
eval-buffer(#<buffer *load*> nil
"/Users/dpeschel/share/emacs/site-lisp/debugger-frame-offset-test.el" nil t)
load-with-code-conversion("/Users/dpeschel/share/emacs/site-lisp/debugger-frame-offset-test.el"
"/Users/dpeschel/share/emacs/site-lisp/debugger-frame-offset-test.el" nil nil)
load("/Users/dpeschel/share/emacs/site-lisp/debugger-frame-offset-test.el"
nil nil t)
load-file("~/share/emacs/site-lisp/debugger-frame-offset-test.el")
* call-interactively(load-file)
execute-extended-command(nil)
call-interactively(execute-extended-command)
- ------------------------------------------------------------------------------
8. in debugger, move to a frame, look at what "i" command says
emacs> i
emacs= (t fun6) does not match function name
of frame at cursor
emacs> C-u C-n C-u C-n C-u C-n get to
"call-interactively(load-file)"
frame, last one that I expect
to have a printout
corresponding to a real frame
emacs> i
emacs= (t call-interactively execute-extended-command)
does not match function name
of frame at cursor
emacs> C-n if expectation is right,
going down onscreen
should not have a printout
corresponding to a real frame
emacs> i
emacs= nil does not match any function
emacs> C-x C-c
Procedure -- Apply fix:
- -----------------------
9. switch debug.el versions
shell> rm -f debug.elc
shell> mv -i debug.el debug.el.old
shell> mv -i debug.el.new debug.el
10. byte-compile debug.el
(repeat step #6)
Procedure -- Test fix:
- ----------------------
11. restart emacs, load test case, run test case
(repeat step #7; debugger window contents should be same)
12. in debugger, move to a frame, look at what "i" command says
emacs> i
emacs= (t fun8) matches function name of
frame at cursor
emacs> C-u C-n C-u C-n C-u C-n get to
"call-interactively(load-file)"
frame, which was a boundary
case before the fix was
applied
emacs> i
emacs= (t call-interactively load-file) matches function name of
frame at cursor
emacs> C-n test next frame onscreen,
which was past the boundary
case before the fix was
applied
emacs> i
emacs= (t execute-extended-command nil) matches function name of
frame at cursor
emacs> C-n test next frame onscreen,
boundary case now
emacs= (t call-interactively execute-extended-command)
matches function name of
frame at cursor
emacs> C-x C-c
Procedure -- Undo setup:
- ------------------------
13. undo changes to ~/.emacs
shell> rm ~/.emacs if .emacs didn't exist
before this procedure
shell> mv ~/.emacs.disabled-during-bug-fix ~/.emacs
if .emacs already existed
before this procedure
14. undo changes to working directory
If the directory didn't exist before this procedure:
shell> cd or whatever was the
current directory when WORK
was created
shell> rm -rf $WORK
If the directory did exist before this procedure:
shell> mv debug.el.disabled-during-bug-fix debug.el
if debug.el already existed
before this procedure
shell> mv debug.elc.disabled-during-bug-fix debug.elc
if debug.elc already existed
before this procedure
shell> rm debug.el.patch-test-orig
shell> rm debug.el-patch-test-fix
shell> rm debugger-frame-offset-test.el
shell> rm debug.el.old
shell> rm debug.el.new
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