Subject: RE: bug#12908: 24.3.50; file `emacs_backtrace.txt'?

From: "Drew Adams" <[email-masked]>
Date: Fri, 16 Nov 2012 11:22:51 -0800

> It's written in the current directory of the Emacs process, and only
> if you click NO on the abort dialog.

I don't understand.  If you click NO then you are saying that you do NOT want to
participate in debugging the crash.  Why would Emacs insist in that case in
writing a backtrace file for debugging to your hard drive?

That does not seem very friendly (or useful) on the part of Emacs.

> > I looked in the Emacs manual, the Elisp manual, and NEWS for some
> > information about this file, but found nothing (so there is 
> > a doc bug, at least).
> 
> Right, now fixed (revision 110913 on the trunk).
> 
> > What is the file for
> 
> It contains the call-stack backtrace, which could be used to find the
> sequence of function calls that led to the crash.  Similar to what GDB
> produces when you type "bt".

So it could be used for debugging.  But it is written only if a user says that
s?he does NOT want to debug the crash.

I understand that such a NO means, in particular, that s?he does not want to use
gdb, but it can also mean that s?he does not want to bother with any debugging
etc.  Why assume that s?he wants a backtrace file written?

> > how are users to use it
> 
> Users should include it with their bug reports.

Does my having included it in this bug report help in some way?
I'm guessing no, but would love to be shown wrong.

> If you have the addr2line.exe program on your disk, you can
> produce a more readable backtrace from these numbers, see
> the Emacs user manual for details.

And if you do not have addr2line?  Is the backtrace really useful for anyone in
that case?  Did the backtrace I included here help at all?
(Not rhetorical questions.)

> > and control whether and where it is written
> 
> You can't.  It's always written in the current directory of the Emacs
> process, which is normally a single directory determined by what your
> desktop shortcut says.

Why not let users decide where the file is written, and record that directory
(of the process) as part of the file content (or record it elsewhere)?

Sounds like shades of Unix .core files.  At least there are ways for users to
turn off writing such coredumps (and even ways to turn that off selectively, for
given directories).

You've closed the bug, considering, I imagine, that it is only a doc bug and
that you have now documented it, so end of story.

I don't see it that way.  Emacs is now writing something to arbitrary user
directories.  That is something new and not necessarily always welcome.  Please
consider working on this aspect some more.  Thx.