[lworld] RFR: 8377101: [lworld] Automatically generate value class sources based on source annotations [v2]

[Roger Riggs]

On Fri, 27 Feb 2026 12:53:13 GMT, David Beaumont <duke at openjdk.org> wrote:

>> Adds a new AnnotationProcessor to read the @MigratedValueClass on prospective value classes and generate the equivalent source file with the 'value' keyword at each annotated class declaration.
>> 
>> This adds new PROCESSOR_PATH variable to the compilation macro and use it for annotation processing.
>> This also requires moving the plugin discovery path to the new variable (was in classpath before) because the addition of a '--processor-path' flag disables using the classpath for plugin discovery.
>> 
>> For now this is all limited to `java.base` but that's expandable later easily. There was an issue just enabling it for all modules however (esp. `jdk.incubator` which might be special).
>> 
>> While there is currently no specific unit test for this code, if it were to fail to generate the correct value classes, a lot of other downstream tests would fail.
>
> David Beaumont has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove unused file

make/jdk/src/classes/build/tools/valueclasses/GenValueClasses.java line 1:

> 1: /*

OpenJDK has been moving away from `getXXXX` style names to just XXX, consider doing that here in new code.

make/jdk/src/classes/build/tools/valueclasses/GenValueClasses.java line 100:

> 98:                             + " for annotation processor: " + GenValueClasses.class.getName());
> 99:         }
> 100:         this.outDir = Path.of(outDir.replace('/', File.separatorChar));

Separator replacement is not necessary, windows supports both.

-------------

PR Review Comment: https://git.openjdk.org/valhalla/pull/2180#discussion_r2864584707
PR Review Comment: https://git.openjdk.org/valhalla/pull/2180#discussion_r2864564321