Problems with gdb-ui.

[Nick Roberts <nickrob@gnu.org>]

 > At times, I have had BIG problems with emacs behaving very strangely
 > if gdb is running (or has been running).  
 >
 > For example, I cannot easily C-g out of the minibuffer and bogus
 > stuff seems to be written to the minibuffer (but I'm not sure).
 > 
 > Also emacs once hung retrieving POP mail.

I've no great ideas but I can make suggestions.

 > Enabling debugging gets this result in gdb-debug-log:
 > 
 > ((recv . "\n\x1a\x1aframes-invalid\n")
 >  (recv . "\n\x1a\x1aframes-invalid\n")
 >  (recv . "\n\x1a\x1aframes-invalid\n\n\x1a\x1aframes-invalid\n")
 >  (recv . "\n\x1a\x1aframes-invalid\n")
 >  ...  continues forever ...

That's strange. I would have thought that GDB must be sending something
for that to happen, so that the list had elements like:

   (send . "foo\n")

 > the partial output buffer contains:
 > 
 >         Undefined command: "interpreter".  Try "help".

This is because emacs is trying to access GDB's machine interface (GDB/MI)
which only works in 6.0 onwards. I suspect that the speedbar is present 
(gdb-var-update executes) or you have either tried gud-watch. This output
might not relate to the error but you could try deleting the speedbar or
updating to GDB 6.0 (Fedora has it, I think) or 6.1. This has the benefit
of providing watch expressions if you want them.
 > 
 > My GDB is the one that came with redhat 9.0:
 > 
 > GNU gdb Red Hat Linux (5.3post-0.20021129.18rh)
 > Copyright 2003 Free Software Foundation, Inc.
 > 
 > 
 > 
 > Re. the minibuffer problems, I don't really know what's going on,
 > but could it be that some process filter does (set-buffer nil)
 > and thus throw an error, and then strange things happen with
 > quit or something...  [for an example where that could happen,
 > see code below, there's no check that buffer is non-nil here]
 > 
 > (defun gdb-assembler-custom ()
 >   (let ((buffer (gdb-get-buffer 'gdb-assembler-buffer))
 > 	(pos 1) (address) (flag))
 >     (with-current-buffer buffer
 >       (if (not (equal gdb-current-address "main"))
 > 	  (progn
 > 	    (goto-char (point-min))
 > 	    (if (re-search-forward gdb-current-address nil t)
 > 		(progn
 > 		  (setq pos (point))
 > 		  (beginning-of-line)
 > 		  (or gdb-overlay-arrow-position
 > 		      (setq gdb-overlay-arrow-position (make-marker)))
 > 		  (set-marker gdb-overlay-arrow-position
 > 			      (point) (current-buffer))))))
 >       ;; remove all breakpoint-icons in assembler buffer before updating.
 >       (gdb-remove-breakpoint-icons (point-min) (point-max)))
 >     (with-current-buffer (gdb-get-buffer 'gdb-breakpoints-buffer)
 >       (goto-char (point-min))

I think buffer should always be non-nil here, unless it has been deleted by the
user. You could try replacing gdb-get-buffer with gdb-get-create-buffer.
 
 > 
 > When emacs "hung" in POP mail retrieval, the following backtrace
 > tells me something is bad in gdb:
 > 
 > (gdb) xbacktrace
 > "gdb-look-for-tagged-buffer"
 > "gdb-get-buffer"
 > "gdb-get-create-buffer"
 > "gdb-append-to-partial-output"
 > "gdb-concat-output"
 > "gud-gdba-marker-filter"
 > "apply"
 > "gud-marker-filter"
 > "gud-filter"
 > "accept-process-output"
 > "pop3-read-response"
 > "pop3-open-server"
 > "pop3-movemail"
 > "mail-source-fetch-pop"
 > "funcall"
 > "mail-source-fetch"
 > "nnmail-get-new-mail"
 > "nnml-request-scan"
 > "gnus-request-scan"
 > "gnus-read-active-file-1"
 > "gnus-read-active-file"
 > "gnus-group-get-new-news"
 > "call-interactively"

It looks like the process filter for pop3 has been set to gud-filter. This
presumably could also be something is bad in pop3.

Nick