Refactor varobj_update interface.

* varobj.c (varobj_update): Report changes as vector.  Also
        return not just a list of varobj, but a list of special structures
        that tell what exactly has changed.
        * varobj.h (enum varobj_update_error): Rename to
        varobj_scope_status.
        (struct varobj_update_result_t): New.
        (varobj_update): Adjust prototype.
        * mi/mi-cmd-var.c: Adjust for changes.

gdb/varobj.c

@@ -1120,9 +1120,6 @@ install_new_value (struct varobj *var, struct value *value, int initial)
    expression to see if it's changed.  Then go all the way
    through its children, reconstructing them and noting if they've
    changed.
-   Return value: 
-    < 0 for error values, see varobj.h.
-    Otherwise it is the number of children + parent changed.
 
    The EXPLICIT parameter specifies if this call is result
    of MI request to update this specific variable, or 
@@ -1133,9 +1130,7 @@ install_new_value (struct varobj *var, struct value *value, int initial)
    returns TYPE_CHANGED, then it has done this and VARP will be modified
    to point to the new varobj.  */
 
-int
-varobj_update (struct varobj **varp, struct varobj ***changelist,
-	       int explicit)
+VEC(varobj_update_result) *varobj_update (struct varobj **varp, int explicit)
 {
   int changed = 0;
   int type_changed = 0;
@@ -1146,52 +1141,50 @@ varobj_update (struct varobj **varp, struct varobj ***changelist,
   struct varobj **templist = NULL;
   struct value *new;
   VEC (varobj_p) *stack = NULL;
-  VEC (varobj_p) *result = NULL;
+  VEC (varobj_update_result) *result = NULL;
   struct frame_info *fi;
 
-  /* sanity check: have we been passed a pointer?  */
-  gdb_assert (changelist);
-
   /* Frozen means frozen -- we don't check for any change in
      this varobj, including its going out of scope, or
      changing type.  One use case for frozen varobjs is
      retaining previously evaluated expressions, and we don't
      want them to be reevaluated at all.  */
   if (!explicit && (*varp)->frozen)
-    return 0;
+    return result;
 
   if (!(*varp)->root->is_valid)
-    return INVALID;
+    {
+      varobj_update_result r = {*varp};
+      r.status = VAROBJ_INVALID;
+      VEC_safe_push (varobj_update_result, result, &r);
+      return result;
+    }
 
   if ((*varp)->root->rootvar == *varp)
     {
+      varobj_update_result r = {*varp};
+      r.status = VAROBJ_IN_SCOPE;
+
       /* Update the root variable. value_of_root can return NULL
 	 if the variable is no longer around, i.e. we stepped out of
 	 the frame in which a local existed. We are letting the 
 	 value_of_root variable dispose of the varobj if the type
 	 has changed.  */
       new = value_of_root (varp, &type_changed);
-      
-      /* If this is a floating varobj, and its type has changed,
-	 then note that it's changed.  */
-      if (type_changed)
-	VEC_safe_push (varobj_p, result, *varp);
-      
+      r.varobj = *varp;
+
+      r.type_changed = type_changed;
       if (install_new_value ((*varp), new, type_changed))
-	{
-	  /* If type_changed is 1, install_new_value will never return
-	     non-zero, so we'll never report the same variable twice.  */
-	  gdb_assert (!type_changed);
-	  VEC_safe_push (varobj_p, result, *varp);
-	}
+	r.changed = 1;
       
       if (new == NULL)
-	{
-	  /* This means the varobj itself is out of scope.
-	     Report it.  */
-	  VEC_free (varobj_p, result);
-	  return NOT_IN_SCOPE;
-	}
+	r.status = VAROBJ_NOT_IN_SCOPE;
+
+      if (r.type_changed || r.changed)
+	VEC_safe_push (varobj_update_result, result, &r);
+
+      if (r.status == VAROBJ_NOT_IN_SCOPE)
+	return result;
     }
 
   VEC_safe_push (varobj_p, stack, *varp);
@@ -1221,32 +1214,16 @@ varobj_update (struct varobj **varp, struct varobj ***changelist,
 	  if (install_new_value (v, new, 0 /* type not changed */))
 	    {
 	      /* Note that it's changed */
-	      VEC_safe_push (varobj_p, result, v);
+	      varobj_update_result r = {v};
+	      r.changed = 1;
+	      VEC_safe_push (varobj_update_result, result, &r);
 	      v->updated = 0;
 	    }
 	}
     }
 
-  /* Alloc (changed + 1) list entries.  */
-  changed = VEC_length (varobj_p, result);
-  *changelist = xmalloc ((changed + 1) * sizeof (struct varobj *));
-  cv = *changelist;
-
-  for (i = 0; i < changed; ++i)
-    {
-      *cv = VEC_index (varobj_p, result, i);
-      gdb_assert (*cv != NULL);
-      ++cv;
-    }
-  *cv = 0;
-
   VEC_free (varobj_p, stack);
-  VEC_free (varobj_p, result);
-
-  if (type_changed)
-    return TYPE_CHANGED;
-  else
-    return changed;
+  return result;
 }