Keep on getting this error which is reproducible: ...

# coroutines

[napperley]

Keep on getting this error which is reproducible:

Exception in thread "main" java.lang.NoSuchMethodError: org.digieng.kmqtt.client.MqttClient.connect$default(Lorg/digieng/kmqtt/client/MqttClient;Lorg/digieng/kmqtt/client/MqttConnectionOptions;Lkotlin/coroutines/Continuation;ILjava/lang/Object;)Ljava/lang/Object;
	at org.example.mqtt_test.MainKt$main$1.invokeSuspend(main.kt:11)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
	at kotlinx.coroutines.DispatchedTask.run(Dispatched.kt:241)
	at kotlinx.coroutines.EventLoopImplBase.processNextEvent(EventLoop.common.kt:270)
	at kotlinx.coroutines.BlockingCoroutine.joinBlocking(Builders.kt:79)
	at kotlinx.coroutines.BuildersKt__BuildersKt.runBlocking(Builders.kt:54)
	at kotlinx.coroutines.BuildersKt.runBlocking(Unknown Source)
	at kotlinx.coroutines.BuildersKt__BuildersKt.runBlocking$default(Builders.kt:36)
	at kotlinx.coroutines.BuildersKt.runBlocking$default(Unknown Source)
	at org.example.mqtt_test.MainKt.main(main.kt:8)
	at org.example.mqtt_test.MainKt.main(main.kt)

Which Issue Tracker should I use for creating the issue (Kotlin or KotlinX Coroutines)?

[louiscad]

kotl.in/issue because it seems to be related to how default interface methods are compiled regarding JDK8.

[napperley]

The class that is used (MqttClient) doesn't implement any interface, unless Kotlin does something in behind the hood that I should be aware of.

[napperley]

If it is something to do with default interface methods in Kotlin would the next Kotlin version (1.4?) fix the issue?

[Vsevolod Tolstopyatov [JB]]

it actually looks like an incompatible change in MqttClient libary

[napperley]

Won't be a incompatible change since the KMQTT Client library ( https://gitlab.com/napperley/kmqtt-client ) doesn't use reflection, although the library's JVM module does depend on the Paho MQTT Client library ( https://www.eclipse.org/paho/clients/java/ ) which does use reflection.

[napperley]

Seems as though the issue might be related to KT-24461 ( https://youtrack.jetbrains.com/issue/KT-24461 ) and/or KT-28752 ( https://youtrack.jetbrains.com/issue/KT-28752 ). Below is the definition for the MqttClient.connect function in the Common module ( https://gitlab.com/napperley/kmqtt-client/blob/master/src/jvmMain/kotlin/org/digieng/kmqtt/client/MqttClient.kt#L88 )

suspend fun connect(connOptions: MqttConnectionOptions = MqttConnectionOptions()): MqttError?

[napperley]

Which KT issue should I add a comment on?

[louiscad]

@napperley You can have incompatible changes even without using reflection. That's why most serious JVM libraries strive to keep binary compatibility as much as possible. Check dependencies using that library, they might rely on version different than the one ending in your executable. You might want to align the versions in a way or another.

[napperley]

There are no dependency conflicts between the program and the library. Have even gone so far as to remove all library artifacts, republish the library, do a clean build of the program followed by a Gradle refresh, and run the program again which has the same result as before.

[napperley]

I have created a issue ( https://youtrack.jetbrains.com/issue/KT-34471 ) in the Kotlin Issue Tracker.

[napperley]

@louiscad - If there were compatibility issues then it would be the MPP part ( https://kotlinlang.org/docs/reference/evolution/components-stability.html )