KSP2: Exception when using Moshi KSP and @ JsonQualifier

[Jean-Daniel]

Note: This issue was originally reported on Moshi, but was determined to be a KSP issue from Moshi devs.

When trying to generate Adapter for classes using a @JsonQualifier, KSP fails with the error:

> Task :app:kspDebugKotlin FAILED
e: [ksp] Error preparing ApiUserItem: jdk.proxy5/jdk.proxy5.$Proxy154.value(Unknown Source)
com.squareup.moshi.kotlin.codegen.ksp.MoshiApiUtilKt.generator(MoshiApiUtil.kt:77)
com.squareup.moshi.kotlin.codegen.ksp.JsonClassSymbolProcessor.adapterGenerator(JsonClassSymbolProcessorProvider.kt:122)
com.squareup.moshi.kotlin.codegen.ksp.JsonClassSymbolProcessor.process(JsonClassSymbolProcessorProvider.kt:92)
com.google.devtools.ksp.impl.KotlinSymbolProcessing.execute(KotlinSymbolProcessing.kt:538)
com.google.devtools.ksp.impl.KSPLoader$Companion.loadAndRunKSP(KSPLoader.kt:36)
com.google.devtools.ksp.impl.KSPLoader.loadAndRunKSP(KSPLoader.kt)
…

The class being compiled is simply:

@Retention(AnnotationRetention.RUNTIME)
@JsonQualifier
annotation class ISO8061

@JsonClass(generateAdapter = true)
open class ApiUserItem(
  @field:Json(name = "slug") val slug: String,
  @field:Json(name = "date_added") @field:ISO8061 val date: Long,
)

You can use this reduced test case to reproduce the bug.

git clone https://github.com/Jean-Daniel/moshiksp2
cd moshiksp2
./gradlew :app:assembleDebug
> Task :app:kspDebugKotlin FAILED
…

[ting-yuan]

This is caused by a breaking change in KSP2, where enums in annotations are modeled as KSClassDeclaration, instead of KSType in KSP1. It should be easy for moshi to delete the proxy implementation and simply use KSP's.