static vs. default interface methods and inheritance VM/javac issues
Karen Kinnear
karen.kinnear at oracle.com
Thu Sep 12 11:23:22 PDT 2013
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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