[PUSHED/OBVIOUS] Remove gdb-gdb.gdb breakpoint on disappeared function info_command.

[Philippe Waroquiers]

On Sat, 2020-05-02 at 22:19 +0100, Maciej W. Rozycki wrote:
> On Fri, 1 May 2020, Kevin Buettner via Gdb-patches wrote:
> 
> > I couldn't find any clue from the ChangeLog entries about why that
> > break command was put into the .gdbinit file.  It might be possible to
> > figure out more precisely when it was introduced, but I didn't attempt
> > this.  I doubt that earlier imports would have any additional useful
> > info not already in the ChangeLog entries that I did examine.
> 
>  Hmm, I'm quite badly surprised to see this feature go, and I do hope it 
> has been functionally (and hopefully transparently) replaced with whatever 
> replaced `info_command'.
Neither Tom nor myself we understood the idea (and saw no description)
and as it was broken, it was deemed appropriate to just remove the
breakpoint command from gdb-gdb.gdb.
Sorry if this removal was a bad idea and inappropriate for PUSHED/OBVIOUS rule.

> 
>  Its use was quite obvious to anyone who actually debugged GDB from time 
> to time: it was there so that you could break from the debuggee GDB into 
> the debugger GDB with the use of the `info' command (with no arguments), 
> as obviously using signals like SIGINT for that was quite problematic.  I 
> used to use this feature regularly, up until the last time a couple months 
> back when I switched to non-GDB work.
I do limited GDB debugging, but was not aware of this feature.
I am not sure to understand the problem:
C-c works for me to interrupt GDB, and the top GDB gets
back the control (I typically launch top-gdb separately
and attach to the inferior GDB).
Can you explain more in details the problem this was solving ?


> 
>  So what's the current mechanism to do that?  I do hope to have it the 
> next time I poke at GDB.
If something done in the inferior GDB must trigger the top GDB to regain
control, we could add a specific dummy command
   e.g.  maintenance wake-up-top-gdb
and then have the breakpoint put on the wake_up_top_gdb_command function
implementing this dummy command.

Philippe