RFR: 8271623: Omit enclosing instance fields from inner classes that don't use it [v4]

[Liam Miller-Cushon]

On Mon, 22 Nov 2021 21:14:39 GMT, Vicente Romero <vromero at openjdk.org> wrote:

>> Liam Miller-Cushon has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains four commits:
>> 
>>  - Don't remove enclosing instance fields from serializable classes without serialVersionUIDs
>>  - Enable enclosing instance optimization for --release 18 and newer
>>  - Add a test case with nested inner classes
>>  - 8271623: Omit enclosing instance fields from inner classes that don't use it
>
> src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/Target.java line 210:
> 
>> 208:      * instance state.
>> 209:      */
>> 210:     public boolean omitUnusedPrivateSyntheticEnclosingInstanceFields() {
> 
> nit: what about a shorter name for this one?

SGTM, maybe `optimizeOuterThis`? I'm open to suggestions :)

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PR: https://git.openjdk.java.net/jdk/pull/4966