* src/lisp.h (last_undo_boundary): Declare new var.

* src/keyboard.c (command_loop_1): Set it.
* src/cmds.c (Fself_insert_command): Use it to only remove boundaries that
were auto-added by the command loop.

Fixes: debbugs:11774

src/ChangeLog

+2012-07-18  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+	* lisp.h (last_undo_boundary): Declare new var.
+	* keyboard.c (command_loop_1): Set it.
+	* cmds.c (Fself_insert_command): Use it to only remove boundaries that
+	were auto-added by the command loop (bug#11774).
+
 2012-07-18  Andreas Schwab  <schwab@linux-m68k.org>
 
 	* w32font.c (Qsymbol): Remove local definition.

src/cmds.c

@@ -296,7 +296,10 @@ At the end, it runs `post-self-insert-hook'.  */)
 
   if (remove_boundary
       && CONSP (BVAR (current_buffer, undo_list))
-      && NILP (XCAR (BVAR (current_buffer, undo_list))))
+      && NILP (XCAR (BVAR (current_buffer, undo_list)))
+      /* Only remove auto-added boundaries, not boundaries
+	 added be explicit calls to undo-boundary.  */
+      && EQ (BVAR (current_buffer, undo_list), last_undo_boundary))
     /* Remove the undo_boundary that was just pushed.  */
     BVAR (current_buffer, undo_list) = XCDR (BVAR (current_buffer, undo_list));
 

src/keyboard.c

@@ -1318,6 +1318,9 @@ cancel_hourglass_unwind (Lisp_Object arg)
 }
 #endif
 
+/* The last boundary auto-added to buffer-undo-list.  */
+Lisp_Object last_undo_boundary;
+
 /* FIXME: This is wrong rather than test window-system, we should call
    a new set-selection, which will then dispatch to x-set-selection, or
    tty-set-selection, or w32-set-selection, ...  */
@@ -1565,7 +1568,13 @@ command_loop_1 (void)
 #endif
 
             if (NILP (KVAR (current_kboard, Vprefix_arg))) /* FIXME: Why?  --Stef  */
-              Fundo_boundary ();
+              {
+		Lisp_Object undo = BVAR (current_buffer, undo_list);
+		Fundo_boundary ();
+		last_undo_boundary
+		  = (EQ (undo, BVAR (current_buffer, undo_list))
+		     ? Qnil : BVAR (current_buffer, undo_list));
+	      }
             Fcommand_execute (Vthis_command, Qnil, Qnil, Qnil);
 
 #ifdef HAVE_WINDOW_SYSTEM

src/lisp.h

@@ -2921,7 +2921,7 @@ extern ptrdiff_t find_before_next_newline (ptrdiff_t, ptrdiff_t, ptrdiff_t);
 extern void syms_of_search (void);
 extern void clear_regexp_cache (void);
 
-/* Defined in minibuf.c */
+/* Defined in minibuf.c.  */
 
 extern Lisp_Object Qcompletion_ignore_case;
 extern Lisp_Object Vminibuffer_list;
@@ -2930,25 +2930,25 @@ extern Lisp_Object get_minibuffer (EMACS_INT);
 extern void init_minibuf_once (void);
 extern void syms_of_minibuf (void);
 
-/* Defined in callint.c */
+/* Defined in callint.c.  */
 
 extern Lisp_Object Qminus, Qplus;
 extern Lisp_Object Qwhen;
 extern Lisp_Object Qcall_interactively, Qmouse_leave_buffer_hook;
 extern void syms_of_callint (void);
 
-/* Defined in casefiddle.c */
+/* Defined in casefiddle.c.  */
 
 extern Lisp_Object Qidentity;
 extern void syms_of_casefiddle (void);
 extern void keys_of_casefiddle (void);
 
-/* Defined in casetab.c */
+/* Defined in casetab.c.  */
 
 extern void init_casetab_once (void);
 extern void syms_of_casetab (void);
 
-/* Defined in keyboard.c */
+/* Defined in keyboard.c.  */
 
 extern Lisp_Object echo_message_buffer;
 extern struct kboard *echo_kboard;
@@ -2956,6 +2956,7 @@ extern void cancel_echoing (void);
 extern Lisp_Object Qdisabled, QCfilter;
 extern Lisp_Object Qup, Qdown, Qbottom;
 extern Lisp_Object Qtop;
+extern Lisp_Object last_undo_boundary;
 extern int input_pending;
 extern Lisp_Object menu_bar_items (Lisp_Object);
 extern Lisp_Object tool_bar_items (Lisp_Object, int *);
@@ -2976,13 +2977,13 @@ extern void init_keyboard (void);
 extern void syms_of_keyboard (void);
 extern void keys_of_keyboard (void);
 
-/* Defined in indent.c */
+/* Defined in indent.c.  */
 extern ptrdiff_t current_column (void);
 extern void invalidate_current_column (void);
 extern int indented_beyond_p (ptrdiff_t, ptrdiff_t, EMACS_INT);
 extern void syms_of_indent (void);
 
-/* Defined in frame.c */
+/* Defined in frame.c.  */
 extern Lisp_Object Qonly;
 extern Lisp_Object Qvisible;
 extern void store_frame_param (struct frame *, Lisp_Object, Lisp_Object);
@@ -2995,7 +2996,7 @@ extern Lisp_Object frame_buffer_predicate (Lisp_Object);
 extern void frames_discard_buffer (Lisp_Object);
 extern void syms_of_frame (void);
 
-/* Defined in emacs.c */
+/* Defined in emacs.c.  */
 extern char **initial_argv;
 extern int initial_argc;
 #if defined (HAVE_X_WINDOWS) || defined (HAVE_NS)