compiler accepts incompatible method reference for Sam conversion

[Maurizio Cimadamore]

Ali,
this works for me (using b147 - or the VM bundled in the lambda repo). 
There have been tons of fixes in the MH area lately, so make sure you 
grab a more recent JDK 7 snapshot (I used to see those problems too 
before the latest lambda merge, but now ost of them went away).

Note also that, in cases in which 292 code is still unstable, you can 
switch back to the old generation logic using the -XDuseProxy flag, 
which should remove all 292-related problems (as, by doing so, 
java.lang.reflect.Proxy will be used instead).

I will be pushing a fix for the other issue (incompatible method ref 
erroneously accepted by javac) shortly.

Thanks
Maurizio

On 13/07/11 10:36, Ali Ebrahimi wrote:
> Hi Remi,
>
> On 7/13/11, Rémi Forax<forax at univ-mlv.fr>  wrote:
>> On 07/13/2011 06:01 AM, Ali Ebrahimi wrote:
>>
>> Hi Ali,
>>
>> ...
>>> MethodHandle mh =
>>> MethodHandles.lookup().findStatic(MethodHandleTest.class,
>>> "sTest", MethodType.methodType(void.class,int.class,int.class));
>>> MethodHandle smh = mh.asSpreader(Object[].class,
>>> mh.type().parameterCount());
>>>
>>> smh.invoke(new Object[]{i,i});<===============crash
>>>
>>> main cause: mh.asSpreader
>>>
>>> I don't known this crash appears in jdkb147.
>> What you want here is to use asCollector, not asSpreader.
>> asSpreader requires that the method as already an object array
>> and extract the value from it.
> May be i'm wrong. but this code picked from MethodHandleProxies class
>
>      public static
>      <T>  T asInterfaceInstance(final Class<T>  intfc, final MethodHandle target) {
>          final Method sm = getSingleMethod(intfc);
>          if (sm == null)
>              throw new IllegalArgumentException("not a single-method
> interface: "+intfc.getName());
>          MethodType smMT = MethodType.methodType(sm.getReturnType(),
> sm.getParameterTypes());
>          MethodHandle checkTarget = target.asType(smMT);  // make throw WMT
>          checkTarget =
> checkTarget.asType(checkTarget.type().changeReturnType(Object.class));
>          final MethodHandle vaTarget =
> checkTarget.asSpreader(Object[].class, smMT.parameterCount());
>          return intfc.cast(Proxy.newProxyInstance(
>                  intfc.getClassLoader(),
>                  new Class[]{ intfc, WrapperInstance.class },
>                  new InvocationHandler() {
>                      private Object getArg(String name) {
>                          if ((Object)name ==
> "getWrapperInstanceTarget")  return target;
>                          if ((Object)name == "getWrapperInstanceType")
>    return intfc;
>                          throw new AssertionError();
>                      }
>                      public Object invoke(Object proxy, Method method,
> Object[] args) throws Throwable {
>                          if (method.getDeclaringClass() == WrapperInstance.class)
>                              return getArg(method.getName());
>                          if (method.equals(sm))
>                              return vaTarget.invokeExact(args);
>                          if (isObjectMethod(method))
>                              return callObjectMethod(this, method, args);
>                          throw new InternalError();
>                      }
>                  }));
>      }
>
> and this results in this crash:
> class MethodHandleTest{
> ...
> public static void sTest(int x,int y){
>       //   System.out.println("stest");
>      }
>
>    static interface Sam{
>          void m(int x,int y);
>      }
> ..
> Sam sam = MethodHandleTest#sTest;
>          sam.m(1,1);<==========
>
>> In your example, the call to mh.asSpreader should return a runtime
>> exception,
>> I will investigate why it's not the case when I will be at my office :)
>>
>>> Best Regards,
>>> Ali Ebrahimi
>> regards,
>> Rémi
>>
>>
>> _______________________________________________
>> mlvm-dev mailing list
>> mlvm-dev at openjdk.java.net
>> http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev
>>
> Best Regards,
> Ali Ebrahimi
>