5 files changed, 67 insertions, 18 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 5a376c4ad5b..3d660159a1a 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,12 @@
+2012-02-23  Chong Yidong  <cyd@gnu.org>
+
+        * xfns.c (Fx_create_frame): Avoid window-configuration-change-hook
+        call when setting menu-bar-lines and tool-bar-lines parameters.
+        (unwind_create_frame_1): New helper function.
+
+        * window.c (inhibit_window_configuration_change_hook): New var.
+        (run_window_configuration_change_hook): Obey it.
+
 2012-02-22  Chong Yidong  <cyd@gnu.org>
 
         * xterm.c (x_draw_image_relief): Add missing type check for
diff --git a/src/lisp.h b/src/lisp.h
index 9199c9aabcf..8ddc7ef143d 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -195,12 +195,25 @@ extern int suppress_checking EXTERNALLY_VISIBLE;
      || defined DARWIN_OS || defined __sun)
 /* We also need to be able to specify mult-of-8 alignment on static vars.  */
 # if defined DECL_ALIGN
-/* mark_maybe_object assumes that EMACS_INT values are contiguous,
-   but this is not true on some hosts where EMACS_INT is wider than a pointer,
-   as they may allocate the halves of an EMACS_INT separately.
-   On these hosts USE_LSB_TAG is not needed because the top bits of an
-   EMACS_INT are unused, so define USE_LSB_TAG only on hosts where it
-   might be useful.  */
+/* On hosts where VALBITS is greater than the pointer width in bits,
+   USE_LSB_TAG is:
+
+    a. unnecessary, because the top bits of an EMACS_INT are unused,
+
+    b. slower, because it typically requires extra masking, and
+
+    c. harmful, because it can create Lisp_Object values that are so scrambled
+       that mark_maybe_object cannot decipher them.  mark_maybe_object assumes
+       that EMACS_INT values are contiguous, but a host where EMACS_INT is
+       wider than a pointer might allocate the top half of an EMACS_INT in
+       (say) a 32-bit word on the stack, putting the bottom half in a 32-bit
+       register that is saved elsewhere in a jmp_buf.  When this happens,
+       since USE_LSB_TAG is not defined the bottom half alone is a valid
+       pointer that mark_maybe_pointer can follow; but if USE_LSB_TAG were
+       defined, the bottom half would not be a valid pointer and neither
+       mark_maybe_object nor mark_maybe_pointer would follow it.
+
+   So, define USE_LSB_TAG only on hosts where it might be useful.  */
 #  if UINTPTR_MAX >> VALBITS != 0
 #   define USE_LSB_TAG
 #  endif
diff --git a/src/window.c b/src/window.c
index b50ae71df8c..ac462624495 100644
--- a/src/window.c
+++ b/src/window.c
@@ -124,6 +124,9 @@ static int window_initialized;
 /* Hook to run when window config changes.  */
 static Lisp_Object Qwindow_configuration_change_hook;
 
+/* If non-nil, run_window_configuration_change_hook does nothing.  */
+Lisp_Object inhibit_window_configuration_change_hook;
+
 /* Used by the function window_scroll_pixel_based */
 static int window_scroll_pixel_based_preserve_x;
 static int window_scroll_pixel_based_preserve_y;
@@ -2896,7 +2899,7 @@ run_window_configuration_change_hook (struct frame *f)
     = Fdefault_value (Qwindow_configuration_change_hook);
   XSETFRAME (frame, f);
 
-  if (NILP (Vrun_hooks))
+  if (NILP (Vrun_hooks) || !NILP (inhibit_window_configuration_change_hook))
     return;
 
   /* Use the right buffer.  Matters when running the local hooks.  */
diff --git a/src/window.h b/src/window.h
index ea127ca95a8..f4a5f52b9a5 100644
--- a/src/window.h
+++ b/src/window.h
@@ -810,6 +810,10 @@ extern Lisp_Object Vmouse_window;
 
 extern Lisp_Object Vmouse_event;
 
+/* If non-nil, run_window_configuration_change_hook does nothing.  */
+
+extern Lisp_Object inhibit_window_configuration_change_hook;
+
 EXFUN (Fnext_window, 3);
 EXFUN (Fselect_window, 2);
 EXFUN (Fset_window_buffer, 3);
diff --git a/src/xfns.c b/src/xfns.c
index f00335b5d03..6fcd129e4a4 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -2949,6 +2949,12 @@ unwind_create_frame (Lisp_Object frame)
   return Qnil;
 }
 
+static Lisp_Object
+unwind_create_frame_1 (Lisp_Object val)
+{
+  inhibit_window_configuration_change_hook = val;
+  return Qnil;
+}
 
 static void
 x_default_font_parameter (struct frame *f, Lisp_Object parms)
@@ -3321,17 +3327,31 @@ This function is an internal primitive--use `make-frame' instead.  */)
      happen.  */
   init_frame_faces (f);
 
-  /* The X resources controlling the menu-bar and tool-bar are
-     processed specially at startup, and reflected in the mode
-     variables; ignore them here.  */
-  x_default_parameter (f, parms, Qmenu_bar_lines,
-                       NILP (Vmenu_bar_mode)
-                       ? make_number (0) : make_number (1),
-                       NULL, NULL, RES_TYPE_NUMBER);
-  x_default_parameter (f, parms, Qtool_bar_lines,
-                       NILP (Vtool_bar_mode)
-                       ? make_number (0) : make_number (1),
-                       NULL, NULL, RES_TYPE_NUMBER);
+  /* Set the menu-bar-lines and tool-bar-lines parameters.  We don't
+     look up the X resources controlling the menu-bar and tool-bar
+     here; they are processed specially at startup, and reflected in
+     the values of the mode variables.
+
+     Avoid calling window-configuration-change-hook; otherwise we
+     could get an infloop in next_frame since the frame is not yet in
+     Vframe_list.  */
+  {
+    int count2 = SPECPDL_INDEX ();
+    record_unwind_protect (unwind_create_frame_1,
+                           inhibit_window_configuration_change_hook);
+    inhibit_window_configuration_change_hook = Qt;
+
+    x_default_parameter (f, parms, Qmenu_bar_lines,
+                         NILP (Vmenu_bar_mode)
+                         ? make_number (0) : make_number (1),
+                         NULL, NULL, RES_TYPE_NUMBER);
+    x_default_parameter (f, parms, Qtool_bar_lines,
+                         NILP (Vtool_bar_mode)
+                         ? make_number (0) : make_number (1),
+                         NULL, NULL, RES_TYPE_NUMBER);
+
+    unbind_to (count2, Qnil);
+  }
 
   x_default_parameter (f, parms, Qbuffer_predicate, Qnil,
                        "bufferPredicate", "BufferPredicate",