* src/eval.c: Add `inhibit-debugger'.

(Qinhibit_debugger): New symbol.
(call_debugger): Bind it instead of Qdebug_on_error.
(maybe_call_debugger): Test Vinhibit_debugger.
(syms_of_eval): Define inhibit-debugger.
* src/xdisp.c (set_message): Don't bind Qinhibit_debug_on_message.
(syms_of_xdisp): Remove inhibit-debug-on-message.
* lisp/emacs-lisp/debug.el (debug): Don't bind debug-on-error since
inhibit-debugger is bound instead.

8 files changed, 43 insertions, 32 deletions

diff --git a/etc/NEWS b/etc/NEWS
index af4bcf11dbb..e095ca795e4 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -675,7 +675,15 @@ The interpretation of the DECLS is determined by `defun-declarations-alist'.
 
 ** New error type and new function `user-error'.  Doesn't trigger the debugger.
 
-** New option `debugger-bury-or-kill'.
+** Debugger
+*** New option `debugger-bury-or-kill'.
+
+*** Set `debug-on-message' to enter the debugger when a certain
+message is displayed in the echo area.  This can be useful when trying
+to work out which code is doing something.
+
+*** New var `inhibit-debugger', automatically set to prevent accidental
+recursive invocations.
 
 +++
 ** New utility function `buffer-narrowed-p'.
@@ -1977,10 +1985,6 @@ instead of jumping all the way to the top-level.
 *** Set `debug-on-event' to enter the debugger on events like SIGUSR1.
 This can be useful when `inhibit-quit' is set.
 
-*** Set `debug-on-message' to enter the debugger when a certain
-message is displayed in the echo area.  This can be useful when trying
-to work out which code is doing something.
-
 ** The new function `server-eval-at' allows evaluation of Lisp forms on
 named Emacs server instances.
 
diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index cdc021d192f..202b41891eb 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2012-09-12  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        * emacs-lisp/debug.el (debug): Don't bind debug-on-error since
+        inhibit-debugger is bound instead.
+
 2012-09-11  Bastien Guerry  <bzg@gnu.org>
 
         * subr.el (set-temporary-overlay-map): Add a docstring.
@@ -24,8 +29,8 @@
 
 2012-09-10  Dan Nicolaescu  <dann@gnu.org>
 
-        * vc/diff-mode.el (diff-mode-menu): Bind
-        diff-remove-trailing-whitespace.
+        * vc/diff-mode.el (diff-mode-menu):
+        Bind diff-remove-trailing-whitespace.
 
 2012-09-10  Stefan Monnier  <monnier@iro.umontreal.ca>
 
diff --git a/lisp/emacs-lisp/debug.el b/lisp/emacs-lisp/debug.el
index 188c0800eb8..bdb35e424d0 100644
--- a/lisp/emacs-lisp/debug.el
+++ b/lisp/emacs-lisp/debug.el
@@ -162,8 +162,6 @@ first will be printed into the backtrace buffer."
     (unless noninteractive
       (message "Entering debugger..."))
     (let (debugger-value
-          (debug-on-error nil)
-          (debug-on-quit nil)
           (debugger-previous-state
            (if (get-buffer "*Backtrace*")
                (with-current-buffer (get-buffer "*Backtrace*")
diff --git a/src/ChangeLog b/src/ChangeLog
index f4cae50d8ed..a005b1d80c7 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,13 @@
+2012-09-12  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        * eval.c: Add `inhibit-debugger'.
+        (Qinhibit_debugger): New symbol.
+        (call_debugger): Bind it instead of Qdebug_on_error.
+        (maybe_call_debugger): Test Vinhibit_debugger.
+        (syms_of_eval): Define inhibit-debugger.
+        * xdisp.c (set_message): Don't bind Qinhibit_debug_on_message.
+        (syms_of_xdisp): Remove inhibit-debug-on-message.
+
 2012-09-11  Paul Eggert  <eggert@cs.ucla.edu>
 
         Avoid _setjmp/_longjmp problems with local nonvolatile variables.
diff --git a/src/composite.h b/src/composite.h
index 68f5b27ee42..9462b932c66 100644
--- a/src/composite.h
+++ b/src/composite.h
@@ -113,7 +113,7 @@ extern Lisp_Object composition_temp;
    && (end - start) == COMPOSITION_LENGTH (prop))
 
 /* Return the Nth glyph of composition specified by CMP.  CMP is a
-   pointer to `struct composition'. */
+   pointer to `struct composition'.  */
 #define COMPOSITION_GLYPH(cmp, n)                                       \
   XINT (XVECTOR (XVECTOR (XHASH_TABLE (composition_hash_table)          \
                           ->key_and_value)                              \
diff --git a/src/eval.c b/src/eval.c
index 4f0d6c69a51..8a8a507a1b6 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -69,7 +69,7 @@ Lisp_Object Qautoload, Qmacro, Qexit, Qinteractive, Qcommandp;
 Lisp_Object Qinhibit_quit;
 Lisp_Object Qand_rest;
 static Lisp_Object Qand_optional;
-static Lisp_Object Qdebug_on_error;
+static Lisp_Object Qinhibit_debugger;
 static Lisp_Object Qdeclare;
 Lisp_Object Qinternal_interpreter_environment, Qclosure;
 
@@ -229,7 +229,7 @@ call_debugger (Lisp_Object arg)
   specbind (intern ("debugger-may-continue"),
             debug_while_redisplaying ? Qnil : Qt);
   specbind (Qinhibit_redisplay, Qnil);
-  specbind (Qdebug_on_error, Qnil);
+  specbind (Qinhibit_debugger, Qt);
 
 #if 0 /* Binding this prevents execution of Lisp code during
          redisplay, which necessarily leads to display problems.  */
@@ -1725,6 +1725,7 @@ maybe_call_debugger (Lisp_Object conditions, Lisp_Object sig, Lisp_Object data)
       /* Don't try to run the debugger with interrupts blocked.
          The editing loop would return anyway.  */
       ! INPUT_BLOCKED_P
+      && NILP (Vinhibit_debugger)
       /* Does user want to enter debugger for this kind of error?  */
       && (EQ (sig, Qquit)
           ? debug_on_quit
@@ -3467,7 +3468,7 @@ before making `inhibit-quit' nil.  */);
 
   DEFSYM (Qinhibit_quit, "inhibit-quit");
   DEFSYM (Qautoload, "autoload");
-  DEFSYM (Qdebug_on_error, "debug-on-error");
+  DEFSYM (Qinhibit_debugger, "inhibit-debugger");
   DEFSYM (Qmacro, "macro");
   DEFSYM (Qdeclare, "declare");
 
@@ -3482,6 +3483,12 @@ before making `inhibit-quit' nil.  */);
   DEFSYM (Qclosure, "closure");
   DEFSYM (Qdebug, "debug");
 
+  DEFVAR_LISP ("inhibit-debugger", Vinhibit_debugger,
+               doc: /* Non-nil means never enter the debugger.
+Normally set while the debugger is already active, to avoid recursive
+invocations.  */);
+  Vinhibit_debugger = Qnil;
+
   DEFVAR_LISP ("debug-on-error", Vdebug_on_error,
                doc: /* Non-nil means enter debugger if an error is signaled.
 Does not apply to errors handled by `condition-case' or those
@@ -3491,7 +3498,7 @@ if one of its condition symbols appears in the list.
 When you evaluate an expression interactively, this variable
 is temporarily non-nil if `eval-expression-debug-on-error' is non-nil.
 The command `toggle-debug-on-error' toggles this.
-See also the variable `debug-on-quit'.  */);
+See also the variable `debug-on-quit' and `inhibit-debugger'.  */);
   Vdebug_on_error = Qnil;
 
   DEFVAR_LISP ("debug-ignored-errors", Vdebug_ignored_errors,
diff --git a/src/keyboard.c b/src/keyboard.c
index 42c67f68ede..8091258578c 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -4133,7 +4133,7 @@ kbd_buffer_get_event (KBOARD **kbp,
                 *used_mouse_menu = 1;
 #endif
 #ifdef HAVE_NS
-              /* certain system events are non-key events */
+              /* Certain system events are non-key events.  */
               if (used_mouse_menu
                   && event->kind == NS_NONKEY_EVENT)
                 *used_mouse_menu = 1;
@@ -4161,7 +4161,7 @@ kbd_buffer_get_event (KBOARD **kbp,
          so x remains nil.  */
       x = Qnil;
 
-      /* XXX Can f or mouse_position_hook be NULL here? */
+      /* XXX Can f or mouse_position_hook be NULL here?  */
       if (f && FRAME_TERMINAL (f)->mouse_position_hook)
         (*FRAME_TERMINAL (f)->mouse_position_hook) (&f, 0, &bar_window,
                                                     &part, &x, &y, &t);
diff --git a/src/xdisp.c b/src/xdisp.c
index c1e05d6df15..e9d9595d91e 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -364,7 +364,6 @@ static Lisp_Object Qslice;
 Lisp_Object Qcenter;
 static Lisp_Object Qmargin, Qpointer;
 static Lisp_Object Qline_height;
-static Lisp_Object Qinhibit_debug_on_message;
 
 /* These setters are used only in this file, so they can be private.  */
 static inline void
@@ -10590,8 +10589,6 @@ static void
 set_message (const char *s, Lisp_Object string,
              ptrdiff_t nbytes, int multibyte_p)
 {
-  ptrdiff_t count = SPECPDL_INDEX ();
-
   message_enable_multibyte
     = ((s && multibyte_p)
        || (STRINGP (string) && STRING_MULTIBYTE (string)));
@@ -10601,14 +10598,9 @@ set_message (const char *s, Lisp_Object string,
   message_buf_print = 0;
   help_echo_showing_p = 0;
 
-  if (NILP (Vinhibit_debug_on_message) && STRINGP (Vdebug_on_message)
+  if (STRINGP (Vdebug_on_message)
       && fast_string_match (Vdebug_on_message, string) >= 0)
-    {
-      specbind (Qinhibit_debug_on_message, Qt);
-      call_debugger (list2 (Qerror, string));
-    }
-
-  unbind_to (count, Qnil);
+    call_debugger (list2 (Qerror, string));
 }
 
 
@@ -12800,7 +12792,7 @@ overlay_arrow_at_row (struct it *it, struct glyph_row *row)
                     return make_number (fringe_bitmap);
                 }
 #endif
-              return make_number (-1); /* Use default arrow bitmap */
+              return make_number (-1); /* Use default arrow bitmap.  */
             }
           return overlay_arrow_string_or_property (var);
         }
@@ -29316,11 +29308,6 @@ Its value should be an ASCII acronym string, `hex-code', `empty-box', or
   DEFVAR_LISP ("debug-on-message", Vdebug_on_message,
                doc: /* If non-nil, debug if a message matching this regexp is displayed.  */);
   Vdebug_on_message = Qnil;
-
-  DEFVAR_LISP ("inhibit-debug-on-message", Vinhibit_debug_on_message,
-               doc: /* If non-nil, inhibit `debug-on-message' from entering the debugger.  */);
-  Vinhibit_debug_on_message = Qnil;
-  DEFSYM(Qinhibit_debug_on_message, "inhibit-debug-on-message");
 }