Compile failure with AP and explicit record accessor for type parameter

[Vicente Romero]

Hi Arnold,

Thanks a lot for the detailed bug report. I have created [1] to track it,

Vicente

[1] https://bugs.openjdk.org/browse/JDK-8288130

On 6/9/22 11:46, Arnold Alejo Nunag wrote:
>
> Hello,
>
> Our team at Minecraft Forge (a modding platform for Minecraft: Java 
> Edition) recently found a compiler bug regarding records, type 
> parameters, and explicit types while trying to implement a new 
> feature. I'm led to believe that this is the appropriate place to at 
> least publicize and discuss this compiler-related issue. If not, 
> please point me in the appropriate place to report this, thank you.
>
> In summary, an explicitly declared accessor method for a record 
> component whose type is a type parameter of the record fails to 
> compile /only/ when an annotation processor is present during 
> compilation. Removal of the explicit accessor or the annotation 
> processor(s) makes the class compile as expected.
>
> We've assembled a small reproducible case for this issue:
>
> import javax.annotation.processing.AbstractProcessor;
> import javax.annotation.processing.RoundEnvironment;
> import javax.lang.model.element.TypeElement;
> import java.util.Set;
>
> public class EmptyProcessor extends AbstractProcessor {
>     @Override
>     public boolean process(Set<? extends TypeElement> annotations, 
> RoundEnvironment roundEnv) {
>         return false;
>     }
> }
>
> public record TestRecord<T>(T someValue) {
>     public T someValue() {
>         return this.someValue;
>     }
> }
>
> Put each snippet into the source files `EmptyProcessor.java` and 
> `TestRecord.java` respectively, compile the AP class using `javac 
> EmptyProcessor.java`, and try to compile the record class with the AP 
> present using `javac -processor EmptyProcessor TestRecord.java`. The 
> warnings about the processor's lack of source version and supported 
> annotations can be safely ignored (we used them to confirm that the 
> annotation processor is present). Here is the output from running the 
> above on Java 17:
>
> D:\Dev\Sandbox\javacbug> javac -processor EmptyProcessor TestRecord.java
> warning: No SupportedSourceVersion annotation found on EmptyProcessor, 
> returning RELEASE_6.
> warning: Supported source version 'RELEASE_6' from annotation 
> processor 'EmptyProcessor' less than -source '17'
> warning: No SupportedAnnotationTypes annotation found on 
> EmptyProcessor, returning an empty set.
> TestRecord.java:3: error: invalid accessor method in record TestRecord
>     public T someValue() {
>              ^
>   (return type of accessor method someValue() must match the type of 
> record component someValue)
>   where T is a type-variable:
>     T extends Object declared in record TestRecord
> 1 error
> 3 warnings
>
> We've tested this on Windows against Java 16, 17, 18, as well as the 
> 19 EA (build 25, 2022/6/2), all reference implementations from 
> jdk.java.net, as well as the latest Java 17 for Eclipse Temurin 
> (17.0.3_7) and the test case fails on all those versions. We've also 
> tested this against the Eclipse Compiler for Java, and it compiles 
> successfully both with and without the presence of the AP.
>
> Regards,
> Arnold (@sciwhiz12)
>
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