Re: other weird gdb-mi problems

[Nick Roberts]

Dmitry Dzhus writes:
 > Nick Roberts wrote:
 > 
 > > It's an Emacs problem.  The CLI commands "up" and "down", don't emit any
 > > GDB/MI notifications so Emacs doen't know that the display needs updating.
 > 
 > I've changed `gdb-mi.el` to append `--frame` and `--thread` options to
 > every command it sends to GDB. This is is the recommended way to use
 > GDB/MI, because we can put all frame/thread selection logic to
 > frontend-land completely, without relying on internal state of GDB.
 > That's the way `gdb-mi.el` works now ? select frame/thread on frontend
 > side and append --thread/--frame appropriately. `gdb-thread-number` and
 > `gdb-frame-number` variables reflect current thread (probably
 > buffer-local) and frame selected by Emacs.

The problem here, though, is that when the user command _changes_ the
frame, e.g., "up", the frame number should change to 1 but Emacs sends
the command

 "-stack-info-frame --thread 1 --frame 0"
                                      ^^^
since it doesn't realise that the frame has changed.  It parses the output
and thinks that the frame is still 0.  If it sent:

 "-stack-info-frame --thread 1"

it would get the details of the newly selected frame and realise it had
changed.

 >
 > It's pity that these patches didn't make it to GDB upstream :( I see now
 > that current `=thread-selected` notification implementation in GDB uses
 > a different and perhaps less elegant approach. I've posted a patch to
 > GDB mailing list which adds =frame-selected notification following the
 > current approach. I hope that GDB upstream accepts the patch or
 > reevaluates the one you'd sent before.

The `=thread-selected` implementation is indeed somewhat different to what I
proposed. With regard to the frame-changed notification, I realise now Daniel
Jacobowitz pointed out that it would fire too often:

http://sourceware.org/ml/gdb-patches/2008-05/msg00024.html

I think that's when I added a handler for "-stack-info-frame" referred to
above.


-- 
Nick                                           http://www.inet.net.nz/~nickrob