Bad class file when compiling Micronaut 4.8.1 project

[goeh]

Expected Behavior

The project should compile without errors

Actual Behaviour

I tried to upgrade a project from Micronaut 4.8.0 to 4.8.1 but it fails to compile.

error: cannot access MyAuthenticationClient$Intercepted
  bad class file: .../micronaut/issues/bad-class-file/build/classes/java/main/com/example/MyAuthenticationClient$Intercepted.class
    undeclared type variable: T
    Please remove or make sure it appears in the correct subdirectory of the classpath.
1 error

I see the same problem in multiple projects.

Steps To Reproduce

1. See simple reproducer project
2. Try to compile with ./gradlew build
3. See error

Environment Information

• MacOS 15.3.2
• JDK 21.0.2

Example Application

https://github.com/goeh/bad-class-file

Version

4.8.1

[altro3]

@graemerocher @dstepanov Confirm this bug. Micronaut-core 4.8.10 is broken. I have same error when I tried to update to micronaut-platform 4.8.1.

Looks like the bug with return types with generics, like Mono<SimpleModel>.

From micronaut-openapi:

1. Generated controller interface:

@Generated("io.micronaut.openapi.generator.JavaMicronautServerCodegen")
@Controller
public interface RequestBodyApi {

    /**
     * A method to send a simple model in body
     *
     * @param simpleModel (optional)
     * @return Success (status code 200)
     *         or An unexpected error has occurred (status code default)
     */
    @Post("/sendSimpleModel")
    Mono<@Valid SimpleModel> sendSimpleModel(
        @Body @Nullable(inherited = true) @Valid SimpleModel simpleModel
    );

....
}

2. Introspection with micronaut-core 4.8.9:

@Generated
class $RequestBodyController$Definition$Intercepted extends RequestBodyController implements Intercepted {
    private final Interceptor[][] $interceptors;
    private final ExecutableMethod[] $proxyMethods;
    private final RequestBodyController $target;

    public Mono $$access$$sendSimpleModel(SimpleModel simpleModel) {
        return super.sendSimpleModel(simpleModel);
    }

    public Mono sendSimpleModel(SimpleModel simpleModel) {
        return (Mono)(new MethodInterceptorChain(this.$interceptors[0], this, this.$proxyMethods[0], new Object[]{simpleModel})).proceed();
    }

....
}

3. Introspection with micronaut-core 4.8.10:

// $FF: synthetic class
@Generated
class $RequestBodyController$Definition$Intercepted extends RequestBodyController implements Intercepted {
    private final Interceptor[][] $interceptors;
    private final ExecutableMethod[] $proxyMethods;
    private final RequestBodyController $target;

    public Mono<T> $$access$$sendSimpleModel(SimpleModel simpleModel) {
        return super.sendSimpleModel(simpleModel);
    }

    public Mono<T> sendSimpleModel(SimpleModel simpleModel) {
        return (Mono)(new MethodInterceptorChain(this.$interceptors[0], this, this.$proxyMethods[0], new Object[]{simpleModel})).proceed();
    }

....
}

As you see, with micronaut-core 4.8.10 generated $RequestBodyController$Definition$Intercepted class has wrong return types - Mono<T>, but must be Mono as with micronaut-core 4.8.9

[etremblay]

It may be related. We have a similar error since 4.8.1

import io.micronaut.context.annotation.ConfigurationProperties
import io.micronaut.core.bind.annotation.Bindable

@ConfigurationProperties("application.split-io")
interface SplitIoConfiguration {
    @get:Bindable(defaultValue = "false")
    val enabled: Boolean

    val apiKey: String

    @get:Bindable(defaultValue = "10000")
    val blockUntilReadyTimeout: Int
}

error: cannot access SplitIoConfiguration$Intercepted
  bad class file: /home/edtremblay/kronos/projects/kotlin-lib/feature-splitio-micronaut/build/tmp/kapt3/classes/main/com/equisoft/feature/splitio/micronaut/context/SplitIoConfiguration$Intercepted.class
    undeclared type variable: E
    Please remove or make sure it appears in the correct subdirectory of the classpath.

Similar interfaces do not produce de same problem.

Generate code is

// $FF: synthetic class
@Generated
class SplitIoConfiguration$Intercepted implements SplitIoConfiguration, Introduced {
    private final Interceptor[][] $interceptors;
    private final ExecutableMethod[] $proxyMethods;

    public int getBlockUntilReadyTimeout() {
        return ((Number)(new MethodInterceptorChain(this.$interceptors[0], this, this.$proxyMethods[0])).proceed()).intValue();
    }

    public String getApiKey() {
        return (String)(new MethodInterceptorChain(this.$interceptors[1], this, this.$proxyMethods[1])).proceed();
    }

    public boolean getEnabled() {
        return (Boolean)(new MethodInterceptorChain(this.$interceptors[2], this, this.$proxyMethods[2])).proceed();
    }

    SplitIoConfiguration$Intercepted(BeanResolutionContext arg1, BeanContext arg2, Qualifier arg3, List<E> arg4, InterceptorRegistry arg5) {
        .SplitIoConfiguration.Intercepted.Definition.Exec executableMethods = new .SplitIoConfiguration.Intercepted.Definition.Exec();
        this.$proxyMethods = new ExecutableMethod[]{executableMethods.getExecutableMethodByIndex(0), executableMethods.getExecutableMethodByIndex(1), executableMethods.getExecutableMethodByIndex(2)};
        this.$interceptors = new Interceptor[][]{InterceptorChain.resolveIntroductionInterceptors(arg5, this.$proxyMethods[0], arg4), InterceptorChain.resolveIntroductionInterceptors(arg5, this.$proxyMethods[1], arg4), InterceptorChain.resolveIntroductionInterceptors(arg5, this.$proxyMethods[2], arg4)};
    }
}

[graemerocher]

@dstepanov can you take a look?

[etremblay]

For us, it is fixed in 4.8.2

[altro3]

Confirmed: all works fine with micronaut platform 4.8.2

[goeh]

Same here, 4.8.2 seems to works fine. Thanks for the fast response!