Bug report: Annotation Processor NPE

[sdelamo]

Discussed in https://github.com/micronaut-projects/micronaut-security/discussions/1604

^{Originally posted by **ethanhere** February 21, 2024} Micronaut 4 annotation processor NullPointerException We have an application based on Micronaut 3. It builds and runs fun. Recent we upgrade it with micronaut 4 and we got java.lang.NullPointerException when compiling the project. The maven build message is: [ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.12.1:compile (default-compile) on project service-idm-dao-aws: Compilation failure [ERROR] java.lang.NullPointerException: Cannot invoke "javax.lang.model.element.TypeElement.getKind()" because "type" is null [ERROR] at io.micronaut.annotation.processing.visitor.JavaElementFactory.newSourceClassElement(JavaElementFactory.java:92) [ERROR] at io.micronaut.annotation.processing.TypeElementVisitorProcessor.lambda$process$6(TypeElementVisitorProcessor.java:255) [ERROR] at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197) [ERROR] at java.base/java.util.Iterator.forEachRemaining(Iterator.java:133) [ERROR] at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1939) [ERROR] at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509) [ERROR] at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499) [ERROR] at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:575) [ERROR] at java.base/java.util.stream.AbstractPipeline.evaluateToArrayNode(AbstractPipeline.java:260) [ERROR] at java.base/java.util.stream.ReferencePipeline.toArray(ReferencePipeline.java:616) [ERROR] at java.base/java.util.stream.ReferencePipeline.toArray(ReferencePipeline.java:622) [ERROR] at java.base/java.util.stream.ReferencePipeline.toList(ReferencePipeline.java:627) [ERROR] at io.micronaut.annotation.processing.TypeElementVisitorProcessor.process(TypeElementVisitorProcessor.java:256) [ERROR] at jdk.compiler/com.sun.tools.javac.processing.JavacProcessingEnvironment.callProcessor(JavacProcessingEnvironment.java:1021) [ERROR] at jdk.compiler/com.sun.tools.javac.processing.JavacProcessingEnvironment.discoverAndRunProcs(JavacProcessingEnvironment.java:937) [ERROR] at jdk.compiler/com.sun.tools.javac.processing.JavacProcessingEnvironment$Round.run(JavacProcessingEnvironment.java:1265) [ERROR] at jdk.compiler/com.sun.tools.javac.processing.JavacProcessingEnvironment.doProcessing(JavacProcessingEnvironment.java:1380) [ERROR] at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.processAnnotations(JavaCompiler.java:1272) [ERROR] at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:946) [ERROR] at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:319) [ERROR] at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:178) [ERROR] at jdk.compiler/com.sun.tools.javac.Main.compile(Main.java:64) [ERROR] at jdk.compiler/com.sun.tools.javac.Main.main(Main.java:50) I found a workaround to get the project built by delete an @Facotory annotated class: " package factories; import com.amazonaws.services.kms.AWSKMS; import com.amazonaws.services.kms.AWSKMSClientBuilder; import io.micronaut.context.annotation.Factory; import jakarta.inject.Singleton; @Factory public class AmazonKmsFactory { @Singleton public AWSKMS kms() { return AWSKMSClientBuilder.standard().build(); } } " After analyzing https://github.com/micronaut-projects/micronaut-core/blob/e3f5fdb2726af5fdcab6906ad0db5165cbbb2a24/inject-java/src/main/java/io/micronaut/annotation/processing/TypeElementVisitorProcessor.java#L255 around line 255, I believe there is a bug here: The stack trace I quoted says at io.micronaut.annotation.processing.TypeElementVisitorProcessor.lambda$process$6(TypeElementVisitorProcessor.java:255), it calls JavaElementFactory.newSourceClassElement and within newSourceClassElement method, NullPointerException was thrown. In https://github.com/micronaut-projects/micronaut-core/blob/e3f5fdb2726af5fdcab6906ad0db5165cbbb2a24/inject-java/src/main/java/io/micronaut/annotation/processing/visitor/JavaElementFactory.java#L92 line 92, NPE was thrown because parameter type was null. parameter type was passed from TypeElementVisitorProcessor.java:255 as typeElement if (!elements.isEmpty()) { JavaElementFactory elementFactory = javaVisitorContext.getElementFactory(); JavaElementAnnotationMetadataFactory elementAnnotationMetadataFactory = javaVisitorContext.getElementAnnotationMetadataFactory(); // The visitor X with a higher priority should process elements of A before // the visitor Y which is processing elements of B but also using elements A // Micronaut Data use-case: EntityMapper with a higher priority needs to process entities first // before RepositoryMapper is going to process repositories and read entities List javaClassElements = elements.stream() .map(typeElement -> elementFactory.newSourceClassElement(typeElement, elementAnnotationMetadataFactory)) .toList(); } typeElement is an element in collection named elements. At line 243, it checks elements is not empty, but it doesn't check each element inside not null. In fact a null element should not have been added to this collection. Can someone take a look and fix it?

[ethanhere]

I submitted a issue report in micronaut-core project : https://github.com/micronaut-projects/micronaut-core/issues/10528 Please close this topic.