Access to attributes itereator must be guarded.

com.oracle.truffle.r.nodes.builtin/src/com/oracle/truffle/r/nodes/builtin/base/UnClass.java

@@ -110,11 +110,13 @@ public abstract class UnClass extends RBuiltinNode {
             objectProfile.enter();
             // TODO: should we make S4 objects shareable?
             RS4Object resultS4 = RDataFactory.createS4Object();
-            RAttributes newAttributes = resultS4.initAttributes();
-            for (RAttribute attr : arg.getAttributes()) {
-                newAttributes.put(attr.getName(), attr.getValue());
+            if (arg.getAttributes() != null) {
+                RAttributes newAttributes = resultS4.initAttributes();
+                for (RAttribute attr : arg.getAttributes()) {
+                    newAttributes.put(attr.getName(), attr.getValue());
+                }
+                newAttributes.remove(RRuntime.CLASS_ATTR_KEY);
             }
-            newAttributes.remove(RRuntime.CLASS_ATTR_KEY);
             return resultS4;
         }
         return arg;

com.oracle.truffle.r.nodes/src/com/oracle/truffle/r/nodes/unary/DuplicateNode.java

@@ -51,9 +51,11 @@ public abstract class DuplicateNode extends RBaseNode {
     @Specialization
     protected Object duplicate(RS4Object object) {
         RS4Object newObject = RDataFactory.createS4Object();
-        RAttributes newAttributes = newObject.initAttributes();
-        for (RAttribute attr : object.getAttributes()) {
-            newAttributes.put(attr.getName(), attr.getValue());
+        if (object.getAttributes() != null) {
+            RAttributes newAttributes = newObject.initAttributes();
+            for (RAttribute attr : object.getAttributes()) {
+                newAttributes.put(attr.getName(), attr.getValue());
+            }
         }
         return newObject;
     }

com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/data/RFunction.java

@@ -131,11 +131,13 @@ public final class RFunction extends RSharingAttributeStorage implements RTypedV
     @Override
     public RShareable copy() {
         RFunction newFunction = RDataFactory.createFunction(getName(), getTarget(), getRBuiltin(), getEnclosingFrame(), getFastPath(), containsDispatch());
-        RAttributes newAttributes = newFunction.initAttributes();
-        for (RAttribute attr : getAttributes()) {
-            newAttributes.put(attr.getName(), attr.getValue());
+        if (getAttributes() != null) {
+            RAttributes newAttributes = newFunction.initAttributes();
+            for (RAttribute attr : getAttributes()) {
+                newAttributes.put(attr.getName(), attr.getValue());
+            }
+            newFunction.initAttributes(newAttributes);
         }
-        newFunction.initAttributes(newAttributes);
         return newFunction;
 
     }