From 1535426a11fcf52025cb05bfa261cd9b17ab1cd4 Mon Sep 17 00:00:00 2001
From: Leonid Startsev <leonid.startsev@jetbrains.com>
Date: Thu, 8 Nov 2018 17:43:30 +0300
Subject: [PATCH] Don't add GeneratedSerializer as a supertype for user-defined
 serializers

---
 .../compiler/resolve/KSerializationUtil.kt        |  8 +++++---
 .../resolve/KSerializerDescriptorResolver.kt      | 15 ++++++++++-----
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/resolve/KSerializationUtil.kt b/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/resolve/KSerializationUtil.kt
index 7456b9f1075..1079d76cc02 100644
--- a/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/resolve/KSerializationUtil.kt
+++ b/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/resolve/KSerializationUtil.kt
@@ -41,14 +41,16 @@ fun isKSerializer(type: KotlinType?): Boolean =
 fun isGeneratedKSerializer(type: KotlinType?): Boolean =
     type != null && KotlinBuiltIns.isConstructedFromGivenClass(type, SerialEntityNames.GENERATED_SERIALIZER_FQ)
 
-fun ClassDescriptor.getKSerializerDescriptor(): ClassDescriptor =
+fun ClassDescriptor.getGeneratedSerializerDescriptor(): ClassDescriptor =
     module.getClassFromInternalSerializationPackage(SerialEntityNames.GENERATED_SERIALIZER_CLASS.identifier)
 
 
-fun ClassDescriptor.createGeneratedSerializerTypeFor(argument: SimpleType): SimpleType {
+fun ClassDescriptor.createSerializerTypeFor(argument: SimpleType, baseSerializerInterface: FqName): SimpleType {
     val projectionType = Variance.INVARIANT
     val types = listOf(TypeProjectionImpl(projectionType, argument))
-    return KotlinTypeFactory.simpleNotNullType(Annotations.EMPTY, getKSerializerDescriptor(), types)
+    val descriptor = module.findClassAcrossModuleDependencies(ClassId.topLevel(baseSerializerInterface))
+        ?: throw IllegalArgumentException("Can't locate $baseSerializerInterface")
+    return KotlinTypeFactory.simpleNotNullType(Annotations.EMPTY, descriptor, types)
 }
 
 internal fun extractKSerializerArgumentFromImplementation(implementationClass: ClassDescriptor): KotlinType? {
diff --git a/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/resolve/KSerializerDescriptorResolver.kt b/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/resolve/KSerializerDescriptorResolver.kt
index b4750861453..bb60f6d1f5f 100644
--- a/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/resolve/KSerializerDescriptorResolver.kt
+++ b/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/resolve/KSerializerDescriptorResolver.kt
@@ -57,9 +57,14 @@ object KSerializerDescriptorResolver {
 
     fun addSerializerSupertypes(classDescriptor: ClassDescriptor, supertypes: MutableList<KotlinType>) {
         val serializableClassDescriptor = getSerializableClassDescriptorBySerializer(classDescriptor) ?: return
-        if (supertypes.none(::isKSerializer)) {
-            supertypes.add(classDescriptor.createGeneratedSerializerTypeFor(serializableClassDescriptor.defaultType))
-        }
+        if (supertypes.any(::isKSerializer)) return
+
+        // Add GeneratedSerializer as superinterface for generated $serializer class, and KSerializer to all others
+        val fqName = if (classDescriptor.name == SerialEntityNames.SERIALIZER_CLASS_NAME)
+            SerialEntityNames.GENERATED_SERIALIZER_FQ
+        else
+            SerialEntityNames.KSERIALIZER_NAME_FQ
+        supertypes.add(classDescriptor.createSerializerTypeFor(serializableClassDescriptor.defaultType, fqName))
     }
 
     fun addSerialInfoImplClass(
@@ -196,7 +201,7 @@ object KSerializerDescriptorResolver {
         name: Name
     ): PropertyDescriptor {
         val typeParam = listOf(createProjection(classDescriptor.defaultType, Variance.INVARIANT, null))
-        val propertyFromSerializer = companionDescriptor.getKSerializerDescriptor().getMemberScope(typeParam)
+        val propertyFromSerializer = companionDescriptor.getGeneratedSerializerDescriptor().getMemberScope(typeParam)
             .getContributedVariables(name, NoLookupLocation.FROM_BUILTINS).single()
 
         val propertyDescriptor = PropertyDescriptorImpl.create(
@@ -236,7 +241,7 @@ object KSerializerDescriptorResolver {
             ?: throw AssertionError("Serializer does not implement ${SerialEntityNames.KSERIALIZER_CLASS}??")
 
         val typeParam = listOf(createProjection(serializableClassOnImplSite, Variance.INVARIANT, null))
-        val functionFromSerializer = companionDescriptor.getKSerializerDescriptor().getMemberScope(typeParam)
+        val functionFromSerializer = companionDescriptor.getGeneratedSerializerDescriptor().getMemberScope(typeParam)
             .getContributedFunctions(name, NoLookupLocation.FROM_BUILTINS).single()
 
         functionDescriptor.initialize(