static vs. default interface methods and inheritance VM/javac issues

[Karen Kinnear]

Thank you, we really appreciate all testing.

I have a fix in a prototype in the vm for this. Let me know if you want an early patch. 
Or you can just file a bug and that way you'll know when the fix is officially in the tree.

thanks,
Karen

On Sep 12, 2013, at 10:59 AM, Peter Levart wrote:

> Hi,
> 
> While testing behavior of reflection on default and static interface methods, using self-built JDK from latest tip of jdk8/tl, I found:
> 
> The following program:
> 
> public class DefaultVsStaticInterfaceMethodTest {
>     public interface A {
>         default void m() {
>             System.out.println("A.m() called");
>         }
>     }
> 
>     public interface B {
>         static void m() {
>             System.out.println("B.m() called");
>         }
>     }
> 
>     public interface C extends A, B {
>     }
> 
>     public static void main(String[] args) throws Exception {
>         C c = new C() {};
>         c.m();
>     }
> }
> 
> 
> ...compiles, but gives a runtime error:
> 
> Exception in thread "main" java.lang.AbstractMethodError: Conflicting default methods: DefaultVsStaticInterfaceMethodTest$A.m DefaultVsStaticInterfaceMethodTest$B.m
>     at DefaultVsStaticInterfaceMethodTest$1.m(DefaultVsStaticInterfaceMethodTest.java)
>     at DefaultVsStaticInterfaceMethodTest.main(DefaultVsStaticInterfaceMethodTest.java:28)
> 
> 
> A slightly modified program: "C extends A, B" replaced with "C extends B, A":
> 
> http://cr.openjdk.java.net/~plevart/jdk8-tl/StaticVsDefaultInterfaceMethods/DefaultVsStaticInterfaceMethodTest.java
> 
> ...also compiles, but crashes the VM when run:
> 
> #
> # A fatal error has been detected by the Java Runtime Environment:
> #
> #  SIGSEGV (0xb) at pc=0x00007fd4d5020bf9, pid=9964, tid=140552419804928
> #
> # JRE version: OpenJDK Runtime Environment (8.0) (build 1.8.0-internal-peter_2013_09_12_16_29-b00)
> # Java VM: OpenJDK 64-Bit Server VM (25.0-b48 mixed mode linux-amd64 compressed oops)
> # Problematic frame:
> # j  DefaultVsStaticInterfaceMethodTest.main([Ljava/lang/String;)V+9
> #
> # Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
> #
> # An error report file with more information is saved as:
> # /home/peter/work/git/jdk8-tl/out/production/test/hs_err_pid9964.log
> #
> # If you would like to submit a bug report, please visit:
> #   http://bugreport.sun.com/bugreport/crash.jsp
> #
> Aborted (core dumped)
> 
> 
> Here's the hs_err_pid file:
> 
> http://cr.openjdk.java.net/~plevart/jdk8-tl/StaticVsDefaultInterfaceMethods/hs_err_pid9964.log
>  
> 
> 
> Regards, Peter
> 

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