Hi Jim, 


> > > Attached is a fix for PR 1971. This inserts a breakpoint at the return
> > > address for a function that does not have a previous frame which is what
> > > you have in the case of main. This would however not stop after the
> > > return from main because the semantics of the next command would not
> > > stop the execution in any place where there is no debug information.
> > >
> > > Tested on native x86 with today's head as well as 6.4 branch with no
> > > extra regressions .
> >
> > Is this the behavior we actually want?  Where the user hasn't "set
> > backtrace past-main on", isn't it the correct behavior for GDB to
> > allow the program to exit when doing a 'next' out of main?  (I assume
> > that, if one does a 'set backtrace past-main on', then 'next' works as
> > you suggest it should.)
> 
> Oh, wait.  I might understand better now.  The current behavior is a
> segfault, as get_prev_frame returns NULL.  The code you patched is
> clearly wrong as it stands, since it doesn't account for that
> possibility.  The behavior with your patch is that 'next' from main
> causes the program to run to completion when past-main is off, as I
> suggested it ought.  Right?

Right . Thats the intended behaviour. The debuggee would run to
completion depending  on whether there exists debug info beyond main or
not. 

> I see three uses of insert_step_resume_breakpoint_at_frame
> (get_prev_frame (get_current_frame ())) in infrun.c; would it be
> reasonable to add a new function in the
> insert_step_resume_breakpoint_at_* family,
> insert_step_resume_breakpoint_at_caller (say), that sets the
> step-resume breakpoint at a sal built from the given frame's return
> address?
> 
> I think you'd want to use frame_pc_unwind in that function, and not
> gdbarch_unwind_pc.
> 

 Here's an updated patch that uses a new function
insert_step_resume_breakpoint_at_caller and frame_pc_unwind as suggested
which has been tested on x86-linux with an extra pass in
watchthreads.exp, I am still not sure why this gets fixed by this.. 

 Ok to commit ? 

2006-01-04  Ramana Radhakrishnan  <ramana.radhakrishnan@codito.com>

       PR 1971
       * infrun.c (insert_step_resume_breakpoint_at_caller):New
function.
       (handle_inferior_event):Use above.


cheers
Ramana
-- 
Ramana Radhakrishnan
GNU Tools
codito ergo sum (www.codito.com)