RFR: 8246778: Compiler implementation for Sealed Classes (Second Preview) [v2]
Mandy Chung
mchung at openjdk.java.net
Mon Nov 30 19:36:02 UTC 2020
On Mon, 30 Nov 2020 15:59:07 GMT, Jan Lahoda <jlahoda at openjdk.org> wrote:
>> This pull request replaces https://github.com/openjdk/jdk/pull/1227.
>>
>> From the original PR:
>>
>>> Please review the code for the second iteration of sealed classes. In this iteration we are:
>>>
>>> * Enhancing narrowing reference conversion to allow for stricter checking of cast conversions with respect to sealed type hierarchies
>>>
>>> * Also local classes are not considered when determining implicitly declared permitted direct subclasses of a sealed class or sealed interface
>>>
>>> * renaming Class::permittedSubclasses to Class::getPermittedSubclasses, still in the same method, the return type has been changed to Class<?>[] instead of the previous ClassDesc[]
>>>
>>> * adding code to make sure that annotations can't be sealed
>>>
>>> * improving some tests
>>>
>>>
>>> TIA
>>>
>>> Related specs:
>>> [Sealed Classes JSL](http://cr.openjdk.java.net/~gbierman/jep397/jep397-20201104/specs/sealed-classes-jls.html)
>>> [Sealed Classes JVMS](http://cr.openjdk.java.net/~gbierman/jep397/jep397-20201104/specs/sealed-classes-jvms.html)
>>> [Additional: Contextual Keywords](http://cr.openjdk.java.net/~gbierman/jep397/jep397-20201104/specs/contextual-keywords-jls.html)
>>
>> This PR strives to reflect the review comments from 1227:
>> * adjustments to javadoc of j.l.Class methods
>> * package access checks in Class.getPermittedSubclasses()
>> * fixed to the narrowing conversion/castability as pointed out by Maurizio
>
> Jan Lahoda has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 12 commits:
>
> - Improving getPermittedSubclasses javadoc.
> - Merge branch 'master' into JDK-8246778
> - Moving checkPackageAccess from getPermittedSubclasses to a separate method.
> - Improving getPermittedSubclasses() javadoc.
> - Enhancing the Class.getPermittedSubclasses() test to verify behavior both for sealed classes in named and unnamed modules.
> - Removing unnecessary file.
> - Tweaking javadoc.
> - Reflecting review comments w.r.t. narrowing conversion.
> - Improving checks in getPermittedSubclasses()
> - Merging master into JDK-8246778
> - ... and 2 more: https://git.openjdk.java.net/jdk/compare/6e006223...4d484179
src/java.base/share/classes/java/lang/Class.java line 4463:
> 4461: * @apiNote
> 4462: * Sealed class or interface has no relationship with
> 4463: * {@linkplain Package#isSealed package sealing}.
Package sealing is legacy. Remi suggests to take out this api note which sounds good to me.
The API note in Package::isSealed has made this clear which has no relationship with sealed class or interface.
src/java.base/share/classes/java/lang/Class.java line 4415:
> 4413: * array.
> 4414: *
> 4415: * @return an array of class objects of the permitted subclasses of this class or interface
Nit: s/class objects/{@code Class} objects/
-------------
PR: https://git.openjdk.java.net/jdk/pull/1483
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