IssueTracker

Fixed in 1.5.30

You need to use version 1.5.30 of the Kotlin Gradle plugin or later, which should be compatible with all recent versions of the Android Gradle Plugin. The only other thing to keep in mind is that the fix is only implemented on the IR backend, which is the default since Kotlin 1.5. If you explicitly pass -Xuse-old-backend to the compiler you will not see the fix.

I am facing this error right now. I am using kotlin version 1.5.31 and gradle version 7.0.3. The error says:

error: unexpected type
    public static final android.os.Parcelable.Creator<long> CREATOR = null;
                                                      ^

And this is the class I am trying to parcelize:

@Parcelize
@JvmInline
value class Amount(
    val value: Long = 0
) : Parcelable

You are using the old compiler backend. Since we're using the IR backend by default since Kotlin 1.5 you just have to remove the -Xuse-old-backend option and the bug will be fixed.

But I don't have that flag in my build.gradle. I even tried setting useIR = true in kotlinOptions but that too didn't work.

I've tried on AGP 7.0.3 with Kotlin 1.5.31 and 1.6.10, using IR backend, and I'm getting this compile error

org.jetbrains.kotlin.backend.common.BackendException: Backend Internal error: Exception during IR lowering
File being compiled: /Users/myuser/Documents/Source/GitHub/abc/efg/src/main/java/com/abc/efg/MyClass.kt
The root cause java.lang.NullPointerException was thrown at: org.jetbrains.kotlin.ir.util.IrUtilsKt.getTypeSubstitutionMap(IrUtils.kt:533)

here is the class

@JvmInline
@Parcelize
value class MyClass<T>(val value: String) : Parcelable

For me what seems to be causing the issue is :

apply plugin: 'kotlin-kapt'

I'm playing around with DataBinding and only after adding it and "kapt" has the error appeared. Before that it was completely fine.

Thanks a lot for the reports and especially to mirceagighi@gmail.com for pointing out the link to kapt! What's going on is that kapt is still using the old backend when generating stubs. When both kapt and parcelize are enabled this causes errors in parcelize when using features that were never implemented with the old backend.

Fortunately, the kapt implementation with the new backend is already being worked on, and you can track the progress in KT-49682. I will leave this bug open until the new kapt implementation is merged. It will likely ship with Kotlin 1.7.0.

Meanwhile you should be able to disable the parcelize plugin when generating kapt stubs. I'll try to figure out if there's an easy way to do this in gradle.

Update from https://youtrack.jetbrains.com/issue/KT-49682:

December 2022
We’ve added support for kapt in the new JVM IR backend in Kotlin 1.7.20, available via a flag. See the documentation for more information on how to enable it.

Plans
We plan to enable this behavior by default in v1.8.20 (KT-53135).

The flag to enable the JVM_IR backend for kapt in 1.7.20 is kapt.use.jvm.ir=true in gradle.properties.