Unable to use UInt in custom serializer

[msrd0]

Describe the bug

I tried to use UInt in a custom serializer. Unfortunately, it throws an exception at runtime.

To Reproduce

@Serializable(with = Foo.Serializer::class)
class Foo(val bar: UInt) {
	internal class Serializer : KSerializer<Foo> {
		override val descriptor: SerialDescriptor =
			buildClassSerialDescriptor("org.example.Foo") {
				element<UInt>("bar")
			}
		// ...
	}
}

This produces the following exception at runtime:

kotlinx.serialization.SerializationException: Serializer for class 'UInt' is not found.
Mark the class as @Serializable or provide the serializer explicitly.
	at kotlinx.serialization.internal.Platform_commonKt.serializerNotRegistered(Platform.common.kt:91)

The first line in the stacktrace pointing at my code is at the element<UInt>("bar") line.

Environment

• Kotlin version: 1.5.0
• Library version: both 1.1.0 and 1.2.1 produce this exception
• Kotlin platforms: JVM
• Gradle version: 7.0
• Java version: 11.0.11 (OpenJDK)

[sandwwraith]

As a workaround, you can use element("bar", UInt.serializer().descriptor)

[msrd0]

@sandwwraith Using Class.serializer() only seems to work for types defined in the same module with @Serializable annotation, using UInt.serializer() (or String.serializer()) produces the following compile error:

Unresolved reference. None of the following candidates is applicable because of receiver type mismatch: 
public fun <T : Any> KClass<TypeVariable(T)>.serializer(): KSerializer<TypeVariable(T)> defined in kotlinx.serialization
public inline fun <reified T> SerializersModule.serializer(): KSerializer<TypeVariable(T)> defined in kotlinx.serialization
public fun SerializersModule.serializer(type: Type): KSerializer<Any> defined in kotlinx.serialization
public fun SerializersModule.serializer(type: KType): KSerializer<Any?> defined in kotlinx.serialization

[sandwwraith]

Try to import this function:

kotlinx.serialization/core/commonMain/src/kotlinx/serialization/builtins/BuiltinSerializers.kt

Line 198 in ac54504

public fun UInt.Companion.serializer(): KSerializer<UInt> = UIntSerializer