I'm upgrading to Kotlin 2.0.0 and serialization 1.7.0-RC. I have an issue when using `@file:UseConte...

# serialization

[Robert Jaros]

I'm upgrading to Kotlin 2.0.0 and serialization 1.7.0-RC. I have an issue when using @file:UseContextualSerialization with expect/actual typealias. More in thread.

[Robert Jaros]

I'm using a serializable type, which is declared using expect in common module and implemented as actual typealias on jvm target.

[Robert Jaros]

common:

expect class LocalDateTime

jvm:

actual typealias LocalDateTime = java.time.LocalDateTime

[Robert Jaros]

The type is serlializable with a custom serializer registered in my app.

[Robert Jaros]

With Kotlin 1.9, I've been using @file:UseContextualSerialization to define serializable classes in common code using my type, e.g.:

@file:UseContextualSerialization(LocalDateTime::class)

package com.example

import kotlinx.serialization.Serializable
import kotlinx.serialization.UseContextualSerialization
import io.kvision.types.LocalDateTime

@Serializable
data class Address(
    val id: Int? = 0,
    val firstName: String? = null,
    val lastName: String? = null,
    val createdAt: LocalDateTime? = null,
)

[Robert Jaros]

But with Kotlin 2.0.0 it doesn't work anymore.

[Robert Jaros]

The compiler somehow resolves my common type to a platform type and fails with an error:

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

[Robert Jaros]

It still works correctly when using @Contextual annotation directly on the property:

@Serializable
data class Address(
    val id: Int? = 0,
    val firstName: String? = null,
    val lastName: String? = null,
    @Contextual val createdAt: LocalDateTime? = null,
)

but it's a problem when I have many classes with many fields.

[Robert Jaros]

Is this a known issue?

[Robert Jaros]

Should I fill a bug report?

[Robert Jaros]

https://github.com/Kotlin/kotlinx.serialization/issues/2704