On Wed, 25 May 2022 00:35:24 GMT, Joe Darcy <da...@openjdk.org> wrote:

>> This is an early review of changes to better model JVM access flags, that is 
>> "modifiers" like public, protected, etc. but explicitly at a VM level.
>> Language level modifiers and JVM level access flags are closely related, but 
>> distinct. There are concepts that overlap in the two domains (public, 
>> private, etc.), others that only have a language-level modifier (sealed), 
>> and still others that only have an access flag (synthetic).
>> The existing java.lang.reflect.Modifier class is inadequate to model these 
>> subtleties. For example, the bit positions used by access flags on different 
>> kinds of elements overlap (such as "volatile" for fields and "bridge" for 
>> methods. Just having a raw integer does not provide sufficient context to 
>> decode the corresponding language-level string. Methods like 
>> Modifier.methodModifiers() were introduced to cope with this situation.
>> With additional modifiers and flags on the horizon with projects like 
>> Valhalla, addressing the existent modeling deficiency now ahead of time is 
>> reasonable before further strain is introduced.
>> This PR in its current form is meant to give the overall shape of the API. 
>> It is missing implementations to map from, say, method modifiers to access 
>> flags, taking into account overlaps in bit positions.
>> The CSR https://bugs.openjdk.java.net/browse/JDK-8281660 will be filled in 
>> once the API is further along.
> Joe Darcy has updated the pull request with a new target base due to a merge 
> or a rebase. The incremental webrev excludes the unrelated changes brought in 
> by the merge/rebase. The pull request contains 32 additional commits since 
> the last revision:
>  - Target JDK 20 rather than 19.
>  - Merge branch 'master' into JDK-8266670
>  - Add mask values to constants' javadoc.
>  - Implement review feedback from mlchung.
>  - Fix type in @throws tag.
>  - Merge branch 'master' into JDK-8266670
>  - Respond to review feedback.
>  - Merge branch 'master' into JDK-8266670
>  - Make workding changes suggested in review feedback.
>  - Merge branch 'master' into JDK-8266670
>  - ... and 22 more: 
> https://git.openjdk.java.net/jdk/compare/43363358...05cf2d8b

With the `AccessFlag` API, what is the role of the `Modifier` API going 
forward?   [Value Objects JEP](https://openjdk.java.net/jeps/8277163) defines 
the new `identity` and `value` modifiers.  [PR 
#698](https://github.com/openjdk/valhalla/pull/698) proposes to add 
`Modifier.IDENTITY` and `Modifier.VALUE` constants as  the `identity` and 
`value` modifiers are encoded in a class file using the `ACC_IDENTITY` and 
`ACC_VALUE` flags.  However, with the new improved `AccessFlag` API, the new 
flags will be defined in the `AccessFlag` API.  I think we should avoid adding 
the new flags in `Modifier` and leave it for the existing usage.  Use 
`AccessFlag` for new features.


PR: https://git.openjdk.java.net/jdk/pull/7445

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