[JVM] Don't warn about illegal reflective access

... on Java 9 and newer.

Author: usev6

src/vm/jvm/runtime/org/perl6/nqp/runtime/Ops.java

@@ -139,11 +139,35 @@
 import org.perl6.nqp.sixmodel.reprs.VMIterInstance;
 import org.perl6.nqp.sixmodel.reprs.VMThreadInstance;
 
+import sun.misc.Unsafe;
+
 /**
  * Contains complex operations that are more involved than the simple ops that the
  * JVM makes available.
  */
 public final class Ops {
+    /**
+     * Temporary workaround to avoid warnings about 'illegal reflective access'
+     * (taken from https://stackoverflow.com/a/46458447).
+     * Please note that this is needed for Rakudo, too.
+     * Once something else (e.g. VarHandle) is used instead
+     * of sun.misc.Unsafe this workaround can be removed.
+     */
+    public static void disableWarning() {
+        try {
+            Field theUnsafe = Unsafe.class.getDeclaredField("theUnsafe");
+            theUnsafe.setAccessible(true);
+            Unsafe u = (Unsafe)theUnsafe.get(null);
+
+            Class cls = Class.forName("jdk.internal.module.IllegalAccessLogger");
+            Field logger = cls.getDeclaredField("logger");
+            u.putObjectVolatile(cls, u.staticFieldOffset(logger), null);
+        }
+        catch (Exception e) {
+            // ignore (that's the raison d'être for this method)
+        }
+    }
+
     /* I/O opcodes */
     public static String print(String v, ThreadContext tc) {
         tc.gc.out.print(v);