--- a/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/main/JavaCompiler.java	Mon Aug 31 15:50:20 2015 +0100
+++ b/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/main/JavaCompiler.java	Mon Aug 31 17:33:34 2015 +0100
@@ -87,7 +87,7 @@
  */
 public class JavaCompiler {
     /** The context key for the compiler. */
-    protected static final Context.Key<JavaCompiler> compilerKey = new Context.Key<>();
+    public static final Context.Key<JavaCompiler> compilerKey = new Context.Key<>();
 
     /** Get the JavaCompiler instance for this context. */
     public static JavaCompiler instance(Context context) {
@@ -821,7 +821,7 @@
         // as a JavaCompiler can only be used once, throw an exception if
         // it has been used before.
         if (hasBeenUsed)
-            throw new AssertionError("attempt to reuse JavaCompiler");
+            checkReusable();
         hasBeenUsed = true;
 
         // forcibly set the equivalent of -Xlint:-options, so that no further
@@ -898,6 +898,10 @@
         }
     }
 
+    protected void checkReusable() {
+        throw new AssertionError("attempt to reuse JavaCompiler");
+    }
+
     /**
      * Set needRootClasses to true, in JavaCompiler subclass constructor
      * that want to collect public apis of classes supplied on the command line.