diff -r 69b191cb1d7e -r 4079713129dd langtools/src/share/classes/com/sun/tools/javac/util/Log.java
--- a/langtools/src/share/classes/com/sun/tools/javac/util/Log.java	Wed May 15 00:00:39 2013 -0700
+++ b/langtools/src/share/classes/com/sun/tools/javac/util/Log.java	Wed May 15 14:00:31 2013 +0100
@@ -214,6 +214,11 @@
     public Set<String> expectDiagKeys;
 
     /**
+     * Set to true if a compressed diagnostic is reported
+     */
+    public boolean compressedOutput;
+
+    /**
      * JavacMessages object used for localization.
      */
     private JavacMessages messages;
@@ -597,6 +602,9 @@
                 }
                 break;
             }
+            if (diagnostic.isFlagSet(JCDiagnostic.DiagnosticFlag.COMPRESSED)) {
+                compressedOutput = true;
+            }
         }
     }