RFR: 8292275: javac does not emit SYNTHETIC and MANDATED flags for parameters by default [v7]

[Vicente Romero]

On Thu, 23 Mar 2023 13:17:18 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 26 additional commits since the last revision:
> 
>  - Merge pull request #1 from liachmodded/methodparameters-flags
>    
>  - Update tests
>  - Parity for the parameter flag tests in javac and reflection
>  - Updated RequiredMethodParameterFlagTest, checks against Local classes as well
>  - Merge branch 'master' into methodparameters-flags
>  - Update copyright year
>  - Merge remote-tracking branch 'upstream/master' into fix/enforce-methodparam_attr-if-mandated
>  - address comments
>  - cleanup
>  - add annotation processing test
>  - ... and 16 more: https://git.openjdk.org/jdk/compare/2ad79128...5ac3a214

make/langtools/src/classes/build/tools/symbolgenerator/CreateSymbols.java line 2388:

> 2386:                 for (MethodParameters_attribute.Entry e : params.method_parameter_table) {
> 2387:                     String name = null;
> 2388:                     if (e.name_index != 0) {

could use ternary operator here, but tbh not sure why this change is necessary. The current code is supposed to fail with `ConstantPool.InvalidIndex` exception if the an index is `<= 0`, is this changing now? I mean can `name_index` be `0` now?

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PR Review Comment: https://git.openjdk.org/jdk/pull/9862#discussion_r1179595556