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

[David Beaumont]

On Fri, 27 Feb 2026 11:37:12 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.

An example of output is, given the `Integer.java` source file:

**src/java.base/share/classes/java/lang/Integer.java**

@jdk.internal.MigratedValueClass
@jdk.internal.ValueBased
public final class Integer extends Number


**build/linux-x64/support/gensrc-valueclasses/java.base/java/lang/Integer.java**

@jdk.internal.MigratedValueClass
@jdk.internal.ValueBased
public final value class Integer extends Number

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PR Comment: https://git.openjdk.org/valhalla/pull/2180#issuecomment-3972476375