Kotlin serialization issue

[mipastgt]

I am trying to convert some Kotlin code, which was written for the JVM and uses some Java libraries, to JavaScript (and if that works later to Wasm and C too). This code also uses Kotlin serialization (JSON) which I thought would be no problem because Kotlin serialization does not use reflection. But it turns out that this does not work because some standard Java methods are missing.

These are:

java.lang.Class.isAnonymousClass()Z
java.lang.Class.getEnclosingMethod()Ljava/lang/reflect/Method
java.lang.Class.getEnclosingConstructor()Ljava/lang/reflect/Constructor

Is there any chance that these three missing methods could be implemented?

The full error output is:

Executing 'build'…

> Task :copyWasmGCRuntime
> Task :checkKotlinGradlePluginConfigurationErrors SKIPPED
> Task :processResources NO-SOURCE
> Task :processTeavmResources NO-SOURCE
> Task :processTestResources NO-SOURCE
> Task :compileKotlin
> Task :compileJava NO-SOURCE
> Task :classes UP-TO-DATE
> Task :compileTeavmKotlin NO-SOURCE
> Task :compileTeavmJava NO-SOURCE
> Task :teavmClasses UP-TO-DATE

> Task :generateWasmGC FAILED

[Incubating] Problems report is available at: file:///Users/mpaus/Projects/tmp/TeaVMTestGradle/build/reports/problems/problems-report.html

Deprecated Gradle features were used in this build, making it incompatible with Gradle 9.0.

You can use '--warning-mode all' to show the individual deprecation warnings and determine if they come from your own scripts or plugins.

For more on this, please refer to https://docs.gradle.org/8.12/userguide/command_line_interface.html#sec:command_line_warnings in the Gradle documentation.
3 actionable tasks: 3 executed
Method java.lang.Class.isAnonymousClass()Z was not found
    at kotlin.jvm.internal.ClassReference$Companion.getClassSimpleName(ClassReference.kt:166)
    at kotlin.jvm.internal.ClassReference.getSimpleName(ClassReference.kt:12)
    at kotlinx.serialization.internal.AbstractPolymorphicSerializerKt.throwSubtypeNotRegistered(AbstractPolymorphicSerializer.kt:114)
    at kotlinx.serialization.PolymorphicSerializerKt.findPolymorphicSerializer(PolymorphicSerializer.kt:109)
    at kotlinx.serialization.json.internal.StreamingJsonEncoder.encodeSerializableValue(StreamingJsonEncoder.kt:250)
    at kotlinx.serialization.json.internal.JsonStreamsKt.encodeByWriter(JsonStreams.kt:99)
    at kotlinx.serialization.json.Json.encodeToString(Json.kt:125)
    at de.mpmediasoft.teavmtest.Client$Companion.dispatch(Client.kt:68)
    at de.mpmediasoft.teavmtest.Client.dispatch(-1)
    at de.mpmediasoft.teavmtest.Client.dispatch$exported$1
Method java.lang.Class.getEnclosingMethod()Ljava/lang/reflect/Method; was not found
    at kotlin.jvm.internal.ClassReference$Companion.getClassSimpleName(ClassReference.kt:169)
    at kotlin.jvm.internal.ClassReference.getSimpleName(ClassReference.kt:12)
    at kotlinx.serialization.internal.AbstractPolymorphicSerializerKt.throwSubtypeNotRegistered(AbstractPolymorphicSerializer.kt:114)
    at kotlinx.serialization.PolymorphicSerializerKt.findPolymorphicSerializer(PolymorphicSerializer.kt:109)
    at kotlinx.serialization.json.internal.StreamingJsonEncoder.encodeSerializableValue(StreamingJsonEncoder.kt:250)
    at kotlinx.serialization.json.internal.JsonStreamsKt.encodeByWriter(JsonStreams.kt:99)
    at kotlinx.serialization.json.Json.encodeToString(Json.kt:125)
    at de.mpmediasoft.teavmtest.Client$Companion.dispatch(Client.kt:68)
    at de.mpmediasoft.teavmtest.Client.dispatch(-1)
    at de.mpmediasoft.teavmtest.Client.dispatch$exported$1
Method java.lang.Class.getEnclosingConstructor()Ljava/lang/reflect/Constructor; was not found
    at kotlin.jvm.internal.ClassReference$Companion.getClassSimpleName(ClassReference.kt:170)
    at kotlin.jvm.internal.ClassReference.getSimpleName(ClassReference.kt:12)
    at kotlinx.serialization.internal.AbstractPolymorphicSerializerKt.throwSubtypeNotRegistered(AbstractPolymorphicSerializer.kt:114)
    at kotlinx.serialization.PolymorphicSerializerKt.findPolymorphicSerializer(PolymorphicSerializer.kt:109)
    at kotlinx.serialization.json.internal.StreamingJsonEncoder.encodeSerializableValue(StreamingJsonEncoder.kt:250)
    at kotlinx.serialization.json.internal.JsonStreamsKt.encodeByWriter(JsonStreams.kt:99)
    at kotlinx.serialization.json.Json.encodeToString(Json.kt:125)
    at de.mpmediasoft.teavmtest.Client$Companion.dispatch(Client.kt:68)
    at de.mpmediasoft.teavmtest.Client.dispatch(-1)
    at de.mpmediasoft.teavmtest.Client.dispatch$exported$1

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':generateWasmGC'.
> Errors occurred during TeaVM build

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
> Get more help at https://help.gradle.org.

BUILD FAILED in 3s
11:50:34: Execution finished 'build'.

[konsoletyper]

Although technically it's possible to implement such methods, practically this does not makes sense and makes life for everyone just worse. Instead, I usually just patch Kotlin runtime bytecode to avoid such calls. In the example all three missing methods are called from AbstractPolymorphicSerializerKt.throwSubtypeNotRegistered, so I'd patch this method instead.