Remove @Serializer support

core/commonMain/src/kotlinx/serialization/Annotations.kt

@@ -105,22 +105,6 @@ public annotation class Serializable(
  * serializer.descriptor.annotations.filterIsInstance<MySerializable>().first().data // <- returns "some_data"
  * ```
  *
- * Additionally, the user-defined serializer can be specified using parameter
- * annotated with [MetaSerializable.Serializer]:
- * ```
- * @MetaSerializable
- * @Target(AnnotationTarget.CLASS)
- * annotation class MySerializable(
- *   @MetaSerializable.Serializer val serializer: KClass<out KSerializer<*>>,
- *   val data: String
- * )
- *
- * @MetaSerializable(serializer = MyDataCustomSerializer::class, data = "some_data")
- * class MyData(...)
- *
- * MyData.serializer() // <- returns MyDataCustomSerializer
- * ```
- *
  * @see Serializable
  * @see SerialInfo
  * @see UseSerializers
@@ -129,10 +113,7 @@ public annotation class Serializable(
 @Target(AnnotationTarget.ANNOTATION_CLASS)
 //@Retention(AnnotationRetention.RUNTIME) // Runtime is the default retention, also see KT-41082
 @ExperimentalSerializationApi
-public annotation class MetaSerializable {
-    @Target(AnnotationTarget.PROPERTY)
-    public annotation class Serializer
-}
+public annotation class MetaSerializable
 
 /**
  * Instructs the serialization plugin to turn this class into serializer for specified class [forClass].

core/commonTest/src/kotlinx/serialization/MetaSerializableTest.kt

@@ -1,57 +1,58 @@
 package kotlinx.serialization
 
-import kotlinx.serialization.descriptors.SerialDescriptor
-import kotlinx.serialization.encoding.Decoder
-import kotlinx.serialization.encoding.Encoder
 import kotlin.reflect.KClass
 import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertNotNull
 
 // TODO: for this test to work, kotlin dependency should be updated
 // to serialization plugin with @MetaSerializable support
 class MetaSerializableTest {
 
     @MetaSerializable
-    @Target(AnnotationTarget.CLASS)
-    annotation class MySerializableWithCustomSerializer(@MetaSerializable.Serializer val with: KClass<out KSerializer<*>> = KSerializer::class)
+    @Target(AnnotationTarget.CLASS, AnnotationTarget.PROPERTY)
+    annotation class MySerializable
 
     @MetaSerializable
-    @Target(AnnotationTarget.CLASS)
-    annotation class MySerializableWithInfo(val value: Int, val klass: KClass<*>)
+    @Target(AnnotationTarget.CLASS, AnnotationTarget.PROPERTY)
+    annotation class MySerializableWithInfo(
+        val value: Int,
+        val kclass: KClass<*>
+    )
 
-    @MySerializableWithCustomSerializer(MySerializer::class)
+    @MySerializable
     class Project1(val name: String, val language: String)
 
-    @MySerializableWithCustomSerializer
+    @MySerializableWithInfo(123, String::class)
     class Project2(val name: String, val language: String)
 
-    @MySerializableWithInfo(value = 123, String::class)
+    @MySerializableWithInfo(123, String::class)
+    @Serializable
     class Project3(val name: String, val language: String)
 
-    object MySerializer : KSerializer<Project1> {
-        override val descriptor: SerialDescriptor
-            get() = throw NotImplementedError()
-
-        override fun serialize(encoder: Encoder, value: Project1) = throw NotImplementedError()
-        override fun deserialize(decoder: Decoder): Project1 = throw NotImplementedError()
-    }
+    @Serializable
+    class Wrapper(
+        @MySerializableWithInfo(234, Int::class) val project: Project3
+    )
 
     @Test
-    fun testCustomSerializer() {
-//        val serializer = serializer<Project1>()
-//        assertEquals(serializer, MySerializer)
+    fun testMetaSerializable() {
+        val serializer = serializer<Project1>()
+        assertNotNull(serializer)
     }
 
     @Test
-    fun testDefaultSerializer() {
-//        val serializer = serializer<Project2>()
-//        assertNotNull(serializer)
+    fun testMetaSerializableWithInfo() {
+        val info = serializer<Project2>().descriptor.annotations.filterIsInstance<MySerializableWithInfo>().first()
+        assertEquals(123, info.value)
+        assertEquals(String::class, info.kclass)
     }
 
     @Test
-    fun testDefaultSerialInfo() {
-//        val descriptor = serializer<Project3>().descriptor
-//        val annotation = descriptor.annotations.filterIsInstance<MySerializableWithInfo>().first()
-//        assertEquals(123, annotation.value)
-//        assertEquals(String::class, annotation.klass)
+    fun testMetaSerializableOnProperty() {
+        val info = serializer<Wrapper>().descriptor
+            .getElementAnnotations(0).filterIsInstance<MySerializableWithInfo>().first()
+        assertEquals(234, info.value)
+        assertEquals(Int::class, info.kclass)
     }
 }