java - Lambda/default methods/type erasure quirk/bug using ECJ? -

came accross today , spent ages trying reproduce/figure out happening. can explain why happens or bug type erasure/default methods/lambda's/polymorphism? uncommenting default method makes run fine, have expected work is

output:

works fine object calling consume hello calling accept context hello calling accept via consumer... exception in thread "main" java.lang.abstractmethoderror: method test/lambdatest$$lambda$1.accept(ljava/lang/object;)v abstract     @ test.lambdatest$$lambda$1/834600351.accept(unknown source)     @ test.lambdatest.main(lambdatest.java:24) 

code

package test;  import java.util.function.consumer;  public class lambdatest {      public static void main(string[] args) {         consumer<context> contextignoringobject = new contextunawareobject();         contextignoringobject.accept(new context());          contextignorer contextignoringlambda = () -> {             system.err.println("hello");         };          system.err.println("calling consume");         contextignoringlambda.consume();          system.err.println("calling accept context");         contextignoringlambda.accept(new context());          consumer<context> consumer = contextignoringlambda;          system.err.println("calling accept via consumer...");         consumer.accept(new context());      }      @functionalinterface     public interface contextignorer extends consumer<context> {  //      default void accept(object object) { //          system.err.println("manual bridge method"); //          accept((context)object); //      }          @override         default void accept(context context) {             consume();         }          void consume();      }      public static class contextunawareobject implements contextignorer {          @override         public void consume() {             system.err.println("works fine object");         }      }      public static class context {      }  } 

the problem appears older ecj compiler (3.10.0):

$ java -jar org.eclipse.jdt.core-3.10.0.v20140604-1726.jar -source 1.8 lambdatest.java  $ java lambdatest works fine object calling consume hello calling accept context hello calling accept via consumer... exception in thread "main" java.lang.abstractmethoderror: method lambdatest$$lambda$1.accept(ljava/lang/object;)v abstract     @ lambdatest$$lambda$1/424058530.accept(unknown source)     @ lambdatest.main(lambdatest.java:24) 

using org.eclipse.jdt.core_3.10.0.v20140902-0626.jar or newer solves problem. oracle javac compiler has no such problem. solution update ecj compiler or move javac.