hg: valhalla/valhalla: 8221545: [lworld] Preliminary support for alternate denotation of values and boxes

[Srikanth]

On a quick check, I see that on both directions, we have a compiler 
inserted cast.
As I understand, assignment of V to V? being a widening conversion, the 
cast should go away while
the other direction is still being debated.

This should be straightforward.

Srikanth

On 16/04/19 7:50 PM, Brian Goetz wrote:
> OK, thanks.  Hopefully the new rules will be simpler, as they lean more heavily on subtyping.
>
>
>> On Apr 16, 2019, at 10:18 AM, Srikanth <srikanth.adayapalam at oracle.com> wrote:
>>
>>
>> This change set just introduces the new notation doing nothing new about inserting casts.
>> I will go through the mails discussing this and follow up on a different change set.
>>
>> Thanks
>> Srikanth
>> On 16/04/19 7:32 PM, Brian Goetz wrote:
>>>> This was a request for LW2 - no more boxing.
>>> Right.  I was wondering whether we got there yet, or whether we’d just change the notation to start.
>>>
>>>> We asked for the subtype relationship for both values and for arrays.
>>> For arrays, the covariance rule: T <: U imples T[] <: U[] — should hold uniformly.  No need for special exceptions for value arrays.  Since
>>>
>>>      V <: Object
>>> and
>>>      V? <: Object
>>>
>>> then both V[] and V?[] are <: Object[].
>>>
>>>
>>>
>>>> For LW2 - we requested explicit checkcasts on attempts to narrow.
>>>>
>>>> Agreed that there are discussions about where this is all going after LW2 before LW10.
>>>>
>>>> thanks,
>>>> Karen
>>>>
>>>>> On Apr 16, 2019, at 9:24 AM, Brian Goetz <brian.goetz at oracle.com> wrote:
>>>>>
>>>>> Is the conversion from V to V? still considered a boxing conversion, or is it a widening conversion now?  The language we (currently think we) want is
>>>>>
>>>>>   V <: V?
>>>>>
>>>>> In the other direction, we’re still discussing whether the narrowing conversion is implicit or explicit.
>>>>>
>>>>>> On Apr 16, 2019, at 8:09 AM, Srikanth <srikanth.adayapalam at oracle.com> wrote:
>>>>>>
>>>>>> Notes:
>>>>>>
>>>>>>    - This is the initial commit for supporting V? notation as an alternate for V.box
>>>>>>    - The old .box and .val notation is not withdrawn yet and can still be used, but we should really move over to the new syntax as soon as possible.
>>>>>>    - Existing javac tests have been replicated to use the V? syntax.
>>>>>>    - VBC migration related work is not done yet.
>>>>>>    - One issue that showed up in the parser implementation is the ambiguity at the point of seeing ?
>>>>>>       in  v instanceof Type? exp: exp2; I have arranged for this to be processed as a conditional rather
>>>>>>       than as denoting nullability.
>>>>>>    - On a long value type name the ? suffix does not really stand out ATM, but I guess IDE colorcoding can address this issue.
>>>>>>    - There is one failing test in the langtools suite (jdk/jshell/TypeNameTest.java) I will raise a follow up
>>>>>>      ticket to address this.
>>>>>>    - More testing is required and will be undertaken in the coming weeks. I request/encourage testing by the interested parties too.
>>>>>>
>>>>>> Thanks!
>>>>>> Srikanth
>>>>>>
>>>>>> On 16/04/19 5:32 PM, srikanth.adayapalam at oracle.com wrote:
>>>>>>> Changeset: bf52db1ad4ea
>>>>>>> Author:    sadayapalam
>>>>>>> Date:      2019-04-16 17:31 +0530
>>>>>>> URL:       http://hg.openjdk.java.net/valhalla/valhalla/rev/bf52db1ad4ea
>>>>>>>
>>>>>>> 8221545: [lworld] Preliminary support for alternate denotation of values and boxes
>>>>>>>
>>>>>>> ! src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java
>>>>>>> ! src/jdk.compiler/share/classes/com/sun/tools/javac/comp/AttrContext.java
>>>>>>> ! src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Resolve.java
>>>>>>> ! src/jdk.compiler/share/classes/com/sun/tools/javac/parser/JavacParser.java
>>>>>>> ! src/jdk.compiler/share/classes/com/sun/tools/javac/tree/JCTree.java
>>>>>>> ! src/jdk.compiler/share/classes/com/sun/tools/javac/tree/TreeCopier.java
>>>>>>> ! test/langtools/tools/javac/valhalla/lworld-values/BogusIncompatibility.java
>>>>>>> + test/langtools/tools/javac/valhalla/lworld-values/BoxValCastTest2.java
>>>>>>> + test/langtools/tools/javac/valhalla/lworld-values/GenericsWithQuestion.java
>>>>>>> + test/langtools/tools/javac/valhalla/lworld-values/GenericsWithQuestion.out
>>>>>>> ! test/langtools/tools/javac/valhalla/lworld-values/InnerClassAttributeValuenessTest.java
>>>>>>> + test/langtools/tools/javac/valhalla/lworld-values/IntercastTest2.java
>>>>>>> + test/langtools/tools/javac/valhalla/lworld-values/LookupOnLoxTest2.java
>>>>>>> ! test/langtools/tools/javac/valhalla/lworld-values/Point.java
>>>>>>>