[PATCH] Fix gdb-mi.el to recognize backslashes as quotes

[Sergio Durigan Junior <sergiodj@riseup.net>]

Hi there.

I've sent a message a while ago asking about this question, and in the
end I managed to figure it out.  You can read my question at:

    https://lists.gnu.org/archive/html/emacs-devel/2013-06/msg00482.html

There is also a GDB bug about it:

    http://sourceware.org/bugzilla/show_bug.cgi?id=15596

The fix is rather simple.  gdb-mi.el is not preserving the context and
saving the command being typed when it sees the backslash, and although
it has a "gdb-continuation" variable for that exact purpose, it is not
setting it properly.  All this patch does is to make sure that
gdb-continuation (and gdb-last-command, for that matter) gets set
correctly when it sees a backslash, or when the user presses RET without
nothing in the prompt (i.e., GDB's parlance for "repeat the last
command").  I chose to strip the last backslash, just like GDB does in
the CLI.

I've tested it with real simple examples, and it worked OK.

OK to apply?

lisp/ChangeLog:
2013-07-11  Sergio Durigan Junior  <sergiodj@riseup.net>

	* progmodes/gdb-mi.el (gdb-strip-string-backslash): New function.
	(gdb-send): Correctly handle continuation strings with
	backslashes, and properly set the last command typed.

diff --git a/lisp/progmodes/gdb-mi.el b/lisp/progmodes/gdb-mi.el
index 2c4d6a0..789e7b4 100644
--- a/lisp/progmodes/gdb-mi.el
+++ b/lisp/progmodes/gdb-mi.el
@@ -1759,6 +1759,9 @@ static char *magick[] = {
 As long as GDB is in the recursive reading loop, it does not expect
 commands to be prefixed by \"-interpreter-exec console\".")
 
+(defun gdb-strip-string-backslash (string)
+  (replace-regexp-in-string "\\\\$" "" string))
+
 (defun gdb-send (proc string)
   "A comint send filter for gdb."
   (with-current-buffer gud-comint-buffer
@@ -1766,8 +1769,13 @@ commands to be prefixed by \"-interpreter-exec console\".")
       (remove-text-properties (point-min) (point-max) '(face))))
   ;; mimic <RET> key to repeat previous command in GDB
   (if (not (string= "" string))
-      (setq gdb-last-command string)
-    (if gdb-last-command (setq string gdb-last-command)))
+      (if (not (null gdb-continuation))
+	  (setq gdb-last-command (concat gdb-continuation
+					 (gdb-strip-string-backslash string)
+					 " "))
+	(setq gdb-last-command (gdb-strip-string-backslash string)))
+    (if gdb-last-command (setq string gdb-last-command))
+    (setq gdb-continuation nil))
   (if (or (string-match "^-" string)
 	  (> gdb-control-level 0))
       ;; Either MI command or we are feeding GDB's recursive reading loop.
@@ -1779,10 +1787,13 @@ commands to be prefixed by \"-interpreter-exec console\".")
 	    (setq gdb-control-level (1- gdb-control-level))))
     ;; CLI command
     (if (string-match "\\\\$" string)
-	(setq gdb-continuation (concat gdb-continuation string "\n"))
+	(setq gdb-continuation
+	      (concat gdb-continuation (gdb-strip-string-backslash
+					string)
+		      " "))
       (setq gdb-first-done-or-error t)
       (let ((to-send (concat "-interpreter-exec console "
-                             (gdb-mi-quote string)
+                             (gdb-mi-quote (concat gdb-continuation string " "))
                              "\n")))
         (if gdb-enable-debug
             (push (cons 'mi-send to-send) gdb-debug-log))

--
Sergio