@file:UseContextualSerialization doesn't work on Kotlin 2.0.20-RC2

[vladimirfx]

Describe the bug

@file:UseContextualSerialization annotation simply doesn't work starting from Kotlin 2.0.0 up to 2.0.20-RC2. Compilation fails with:

Serializer has not been found for type 'java.util.UUID'. To use context serializer as fallback, explicitly annotate type or property with @Contextual

To Reproduce

@file:UseContextualSerialization(
    forClasses = [
        UUID::class,
    ]
)

package reproducer

import kotlinx.serialization.Serializable
import kotlinx.serialization.UseContextualSerialization
import java.util.UUID

@Serializable
data class ContextualSerializer(val uuid: UUID)

Reproducer project:
use-contextual-serializer-bug.zip

Expected behavior

The code above should compile normally.

Environment

• Kotlin version: 2.0.0 - 2.0.20-RC2
• Library version: 1.7.1
• Kotlin platforms: JVM
• Gradle version: 8.10
• Java: 21

[sandwwraith]

Thanks for the report. Apparently @file:UseContextualSerialization(UUID::class) or @file:UseContextualSerialization(UUID::class, Date::class) work as expected but @file:UseContextualSerialization(forClasses = [UUID::class]) does not. That is... not what I expected from compiler plugin API.