* print.c (print_object): If Lisp_Save_Value object's pointer

is the address of a memory area containing Lisp_Objects, try
to print them.
* alloc.c (valid_lisp_object_p): Adjust comment.

3 files changed, 46 insertions, 12 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index d0e08317fba..d4794667ead 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -2,6 +2,10 @@
 
         * lisp.h (toplevel): Add two notices to the comment about
         defining a new Lisp data type.
+        * print.c (print_object): If Lisp_Save_Value object's pointer
+        is the address of a memory area containing Lisp_Objects, try
+        to print them.
+        * alloc.c (valid_lisp_object_p): Adjust comment.
 
 2012-12-26  Dmitry Antipov  <dmantipov@yandex.ru>
 
diff --git a/src/alloc.c b/src/alloc.c
index 5a3ba465d81..f33c423ece7 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -4721,12 +4721,12 @@ valid_pointer_p (void *p)
 #endif
 }
 
-/* Return 2 if OBJ is a killed or special buffer object.
-   Return 1 if OBJ is a valid lisp object.
-   Return 0 if OBJ is NOT a valid lisp object.
-   Return -1 if we cannot validate OBJ.
-   This function can be quite slow,
-   so it should only be used in code for manual debugging.  */
+/* Return 2 if OBJ is a killed or special buffer object, 1 if OBJ is a
+   valid lisp object, 0 if OBJ is NOT a valid lisp object, or -1 if we
+   cannot validate OBJ.  This function can be quite slow, so its primary
+   use is the manual debugging.  The only exception is print_object, where
+   we use it to check whether the memory referenced by the pointer of
+   Lisp_Save_Value object contains valid objects.  */
 
 int
 valid_lisp_object_p (Lisp_Object obj)
diff --git a/src/print.c b/src/print.c
index bf86be5622e..b89d5685fba 100644
--- a/src/print.c
+++ b/src/print.c
@@ -2034,14 +2034,44 @@ print_object (Lisp_Object obj, register Lisp_Object printcharfun, int escapeflag
           break;
 
         case Lisp_Misc_Save_Value:
-          strout ("#<save_value ", -1, -1, printcharfun);
           {
-            int len = sprintf (buf, "ptr=%p int=%"pD"d",
-                               XSAVE_VALUE (obj)->pointer,
-                               XSAVE_VALUE (obj)->integer);
-            strout (buf, len, len, printcharfun);
+            int i;
+            struct Lisp_Save_Value *v = XSAVE_VALUE (obj);
+
+            strout ("#<save-value ", -1, -1, printcharfun);
+            if (v->dogc)
+              {
+                int lim = min (v->integer, 8);
+                
+                /* Try to print up to 8 objects we have saved.  Although
+                   valid_lisp_object_p is slow, this shouldn't be a real
+                   bottleneck because such a saved values are quite rare.  */
+
+                i = sprintf (buf, "with %"pD"d objects", v->integer);
+                strout (buf, i, i, printcharfun);
+
+                for (i = 0; i < lim; i++)
+                  {
+                    Lisp_Object maybe = ((Lisp_Object *) v->pointer)[i];
+
+                    if (valid_lisp_object_p (maybe))
+                      {
+                        PRINTCHAR (' ');
+                        print_object (maybe, printcharfun, escapeflag);
+                      }
+                    else
+                      strout (" <invalid>", -1, -1, printcharfun);
+                  }
+                if (i == lim && i < v->integer)
+                  strout (" ...", 4, 4, printcharfun);
+              }
+            else
+              {
+                i = sprintf (buf, "ptr=%p int=%"pD"d", v->pointer, v->integer);
+                strout (buf, i, i, printcharfun);
+              }
+            PRINTCHAR ('>');
           }
-          PRINTCHAR ('>');
           break;
 
         default: