RFR: 8292275: javac does not emit SYNTHETIC and MANDATED flags for parameters by default [v6]

[Hannes Greule]

On Mon, 9 Jan 2023 07:34:41 GMT, Hannes Greule <duke at openjdk.org> wrote:

>> With this change, javac emits the MethodParameters attribute in cases where the JLS requires the information about synthetic and mandated parameters to be stored (see issue).
>> Parameter names are *not* emitted unless the `-parameter` flag is set.
>> 
>> The relevant changes are in `ClassWriter`, where we go through the params to see if we need the attribute if the `-parameter` flag is not set (if it is set, both names and flags will be emitted).
>> For records, the mandated flag wasn't set at all, this is solved by the one line fix in `JavacParser`.
>> 
>> The changes to `CreateSymbols` and `ClassReader` are needed as they weren't able to deal with missing names in the attribute.
>> I also had to update some tests as they got a new constant pool entry.
>> 
>> Only the mandated flag is covered by tests at the moment, as the occurrences are well-specified in the JLS.
>> Please let me know if you want tests for specific appearances of synthetic parameters.
>
> Hannes Greule 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 21 additional commits since the last revision:
> 
>  - Update copyright year
>  - Merge remote-tracking branch 'upstream/master' into fix/enforce-methodparam_attr-if-mandated
>  - address comments
>  - cleanup
>  - add annotation processing test
>  - fix line breaks
>  - add access flag based test
>  - remove spaces from empty lines in text block
>  - add bug number to test
>  - copyright
>  - ... and 11 more: https://git.openjdk.org/jdk/compare/5cb21f18...43780935

Sorry for the late response.

> Our current implementation applies the change of behavior to all `--release/-target` versions. And as far as I see, `MethodParameters` attribute has been properly supported by the Reflection API to filter out synthetic and mandated parameters since [1c54a00](https://github.com/openjdk/jdk/commit/1c54a00f752a54a7a68b09d3df5d3a6081f4fcc8) (Java 8, when `MethodParameters` is introduced). So I suggest to move along by specifying that this change applies to all release/target versions, which will fix the reflection issue on all versions.

I agree with this, I'd be happy if you could update the CSR accordingly.

I will try to address your review comment as soon as possible.

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PR Comment: https://git.openjdk.org/jdk/pull/9862#issuecomment-1479009716