Merge pull request #160 in G/fastr from ~MICK.JORDAN_ORACLE.COM/fastr:bugfix/dimnames to master

* commit '3a3a55e4':
  fix dimnames bug; move code from RVector to vector extract code

com.oracle.truffle.r.nodes/src/com/oracle/truffle/r/nodes/access/vector/CachedExtractVectorNode.java

@@ -295,6 +295,8 @@ final class CachedExtractVectorNode extends CachedVectorNode {
                     Object result;
                     if (dataAt == RNull.instance) {
                         result = RNull.instance;
+                    } else if (positions[i] instanceof RAbstractContainer && ((RAbstractContainer) positions[i]).getLength() == 0) {
+                        result = RNull.instance;
                     } else {
                         result = extract(i, (RAbstractStringVector) dataAt, positions[i], positionProfile[i]);
                     }

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

@@ -398,7 +398,7 @@ public abstract class RVector extends RSharingAttributeStorage implements RShare
                         }
                     } else {
                         RStringVector dimVector = (RStringVector) dimObject;
-                        if (dimVector == null || dimVector.getLength() == 0) {
+                        if (dimVector == null) {
                             newDimNames.updateDataAt(i, RNull.instance, null);
                         } else if (dimVector.getLength() != dimensions[i]) {
                             throw RError.error(invokingNode, RError.Message.DIMNAMES_DONT_MATCH_EXTENT, i + 1);