diff -r 1583c6dd6df7 -r 376a915b4ff0 langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/util/Assert.java
--- a/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/util/Assert.java	Mon Mar 02 10:41:08 2015 +0530
+++ b/langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/util/Assert.java	Thu Mar 05 13:10:49 2015 +0000
@@ -25,6 +25,8 @@
 
 package com.sun.tools.javac.util;
 
+import java.util.function.Supplier;
+
 /**
  * Simple facility for unconditional assertions.
  * The methods in this class are described in terms of equivalent assert
@@ -94,6 +96,15 @@
     }
 
     /** Equivalent to
+     *   assert cond : msg.get();
+     *  Note: message string is computed lazily.
+     */
+    public static void check(boolean cond, Supplier<String> msg) {
+        if (!cond)
+            error(msg.get());
+    }
+
+    /** Equivalent to
      *   assert (o == null) : value;
      */
     public static void checkNull(Object o, Object value) {
@@ -110,6 +121,15 @@
     }
 
     /** Equivalent to
+     *   assert (o == null) : msg.get();
+     *  Note: message string is computed lazily.
+     */
+    public static void checkNull(Object o, Supplier<String> msg) {
+        if (o != null)
+            error(msg.get());
+    }
+
+    /** Equivalent to
      *   assert (o != null) : msg;
      */
     public static <T> T checkNonNull(T t, String msg) {
@@ -119,6 +139,16 @@
     }
 
     /** Equivalent to
+     *   assert (o != null) : msg.get();
+     *  Note: message string is computed lazily.
+     */
+    public static <T> T checkNonNull(T t, Supplier<String> msg) {
+        if (t == null)
+            error(msg.get());
+        return t;
+    }
+
+    /** Equivalent to
      *   assert false;
      */
     public static void error() {