Re: [RFC] Move the frame zero PC check earlier

[Eli Zaretskii <eliz@gnu.org>]

> Date: Thu, 18 May 2006 22:04:09 +0200 (CEST)
> From: Mark Kettenis <mark.kettenis@xs4all.nl>
> CC: pgilliam@us.ibm.com, andrew.stubbs@st.com, brobecker@adacore.com,         drow@false.org, mark.kettenis@xs4all.nl, gdb-patches@sourceware.org
> 
> > The only reason presented in this thread for displaying those frames
> > at all is that it can be an indication of a bug in GDB.
> 
> No.  There are two reasons why we should print those frames, and I
> consider both of them not to be an indication of a bug in GDB.
> 
> 1. Because of a bug in the program you're debugging, it has
>    overwritten the return address on the stack.  Currently this causes
>    the extra frame to be printed signalling the user that something is
>    wrong.  Daniel's patch changes this, but only if the return address
>    is overwritten with zero.
> 
> 2. It may be fundamentally impossible to unwind code produced by an
>    optimizing compiler without additional debug info.  We can't
>    consider the fact that GDB gets the return address wrong if the
>    debug info is missing a bug in GDB.  Again the extra frame signals
>    the user that something is wrong.

I think it was already suggested in this lengthy thread to display
some kind of message to alert the user.  For example:

  (Backtrace terminated due to zero return address.)

Would this make everybody fairly happy to zero in on a solution?