Put String.format behind TruffleBoundary

com.oracle.truffle.r.nodes/src/com/oracle/truffle/r/nodes/builtin/casts/PipelineToCastNode.java

@@ -87,6 +87,7 @@ import com.oracle.truffle.r.runtime.RError;
 import com.oracle.truffle.r.runtime.RInternalError;
 import com.oracle.truffle.r.runtime.RRuntime;
 import com.oracle.truffle.r.runtime.RType;
+import com.oracle.truffle.r.runtime.Utils;
 import com.oracle.truffle.r.runtime.data.RComplex;
 import com.oracle.truffle.r.runtime.data.model.RAbstractComplexVector;
 import com.oracle.truffle.r.runtime.data.model.RAbstractDoubleVector;
@@ -427,7 +428,7 @@ public final class PipelineToCastNode {
                 case Any:
                     return CastToVectorNodeGen.create(step.preserveNonVector);
                 default:
-                    throw RInternalError.shouldNotReachHere(String.format("Unsupported type '%s' in AsVectorStep.", type));
+                    throw RInternalError.shouldNotReachHere(Utils.stringFormat("Unsupported type '%s' in AsVectorStep.", type));
             }
         }
 

com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/Utils.java

@@ -902,4 +902,9 @@ public final class Utils {
         return obj.toString();
     }
 
+    @TruffleBoundary
+    public static String stringFormat(String format, Object... objects) {
+        return String.format(format, objects);
+    }
+
 }