JDK-8221373 (?) Missing checkcast in void-returning lambda

[Maurizio Cimadamore]

I believe so, thanks

Maurizio

On 05/12/2019 10:52, B. Blaser wrote:
> Hi Maurizio,
>
> Thanks for the confirmation, your analysis is similar to my past JBS comment.
> Should I then close this issues as "won't fix"?
>
> Ciao,
> Bernard
>
> On Tue, 3 Dec 2019 at 16:46, Maurizio Cimadamore
> <maurizio.cimadamore at oracle.com> wrote:
>> Hi,
>> sorry for the delay. I've checked JDK-8221373 and, honestly, I'm not
>> sure there's anything to fix. Synthetic casts are only emitted when
>> there's a target. If you rewrite the example, dropping the lambda
>> expression:
>>
>> abstract class Test {
>>
>> interface I<X> {
>>       X d();
>> }
>>
>> abstract <X> I<X> c();
>>
>>     void f() {
>>        this.<Long>c().d(); //1
>>     }
>> }
>>
>> The callsite in (1) is translated as follows:
>>
>>            0: aload_0
>>            1: invokevirtual #2                  // Method c:()LTest$I;
>>            4: invokeinterface #3,  1            // InterfaceMethod
>> Test$I.d:()Ljava/lang/Object;
>>            9: pop
>>           10: return
>>
>> Again, no checkcast here. So I'd say that the fix we did back than
>> brought consistency between these two cases, which is IMHO, a good thing.
>>
>> Maurizio
>>
>> On 30/10/2019 12:40, B. Blaser wrote:
>>> Hi,
>>>
>>> Looking a bit at JDK-8221373, I'd like to make sure we are going in
>>> the right direction before posting a RFR.
>>>
>>> Going back to JDK-8203338, we decided in [1] to take the functional
>>> descriptor's erased return type as translation target which might
>>> cause some side-effects like in Liam's void-returning lambda where no
>>> 'checkcast' are emitted anymore.
>>> So my question is rather simple, should we put in place something
>>> closer to the initial fix I suggested in [2] to preserve the original
>>> erased expression typing?
>>>
>>> Thanks,
>>> Bernard
>>>
>>> [1] http://mail.openjdk.java.net/pipermail/compiler-dev/2018-June/012086.html
>>> [2] http://mail.openjdk.java.net/pipermail/compiler-dev/2018-June/012076.html