Fixes for IR serialization plugin

- Do not insert typeParameters into IrConstructor;
- Set correct property symbol to IrField;

- Use upper bound as a class descriptor for type parameters.
This will allow to get upper bound's KClass in polymorphic serialization.
Fixes https://github.com/Kotlin/kotlinx.serialization/issues/490;

- Lazily add all serializer functions.
Fixes https://github.com/Kotlin/kotlinx.serialization/issues/502;

- Don't generate constructor invocation for abstract(sealed) classes deserializer.
Such code is incorrect anyway (you can't create an instance of abstract class) and causes problems in devirtualization when exporting Native libraries.

plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/backend/ir/GeneratorHelpers.kt

@@ -12,36 +12,23 @@ import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.descriptors.annotations.Annotations
 import org.jetbrains.kotlin.ir.builders.*
 import org.jetbrains.kotlin.ir.declarations.*
-import org.jetbrains.kotlin.ir.declarations.impl.IrPropertyImpl
+import org.jetbrains.kotlin.ir.declarations.impl.*
-import org.jetbrains.kotlin.ir.declarations.impl.IrTypeParameterImpl
-import org.jetbrains.kotlin.ir.declarations.impl.IrValueParameterImpl
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.*
 import org.jetbrains.kotlin.ir.symbols.*
-import org.jetbrains.kotlin.ir.types.IrType
+import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.types.impl.IrSimpleTypeImpl
 import org.jetbrains.kotlin.ir.types.impl.makeTypeProjection
-import org.jetbrains.kotlin.ir.types.makeNotNull
-import org.jetbrains.kotlin.ir.types.toKotlinType
-import org.jetbrains.kotlin.ir.types.typeWith
 import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.js.resolve.diagnostics.findPsi
-import org.jetbrains.kotlin.name.ClassId
+import org.jetbrains.kotlin.name.*
-import org.jetbrains.kotlin.name.FqName
-import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.descriptorUtil.classId
 import org.jetbrains.kotlin.resolve.descriptorUtil.module
-import org.jetbrains.kotlin.types.KotlinType
+import org.jetbrains.kotlin.types.*
-import org.jetbrains.kotlin.types.KotlinTypeFactory
-import org.jetbrains.kotlin.types.TypeProjectionImpl
-import org.jetbrains.kotlin.types.Variance
 import org.jetbrains.kotlin.types.typeUtil.isTypeParameter
 import org.jetbrains.kotlin.types.typeUtil.makeNotNullable
 import org.jetbrains.kotlinx.serialization.compiler.backend.common.findTypeSerializerOrContext
-import org.jetbrains.kotlinx.serialization.compiler.backend.jvm.contextSerializerId
+import org.jetbrains.kotlinx.serialization.compiler.backend.jvm.*
-import org.jetbrains.kotlinx.serialization.compiler.backend.jvm.enumSerializerId
-import org.jetbrains.kotlinx.serialization.compiler.backend.jvm.polymorphicSerializerId
-import org.jetbrains.kotlinx.serialization.compiler.backend.jvm.referenceArraySerializerId
 import org.jetbrains.kotlinx.serialization.compiler.resolve.*
 
 val BackendContext.externalSymbols: ReferenceSymbolTable get() = ir.symbols.externalSymbolTable
@@ -96,10 +83,11 @@ interface IrBuilderExtension {
         ) else compilerContext.externalSymbols.referenceConstructor(descriptor).owner
         c.parent = this
         c.returnType = descriptor.returnType.toIrType()
-        if (!fromStubs || overwriteValueParameters) c.createParameterDeclarations(receiver = null, overwriteValueParameters = overwriteValueParameters)
+        if (!fromStubs || overwriteValueParameters) c.createParameterDeclarations(
-        if (c.typeParameters.isEmpty()) {
+            receiver = null,
-            c.copyTypeParamsFromDescriptor()
+            overwriteValueParameters = overwriteValueParameters,
-        }
+            copyTypeParameters = false
+        )
         c.body = compilerContext.createIrBuilder(c.symbol).at(this).irBlockBody(this.startOffset, this.endOffset) { bodyGen(c) }
         this.addMember(c)
     }
@@ -247,8 +235,10 @@ interface IrBuilderExtension {
             propertyDescriptor
         )
         irProperty.parent = propertyParent
-        irProperty.backingField =
+        irProperty.backingField = generatePropertyBackingField(propertyDescriptor, irProperty).apply {
-            generatePropertyBackingField(propertyDescriptor, irProperty).apply { parent = propertyParent }
+            parent = propertyParent
+            correspondingProperty = irProperty
+        }
         val fieldSymbol = irProperty.backingField!!.symbol
         irProperty.getter = propertyDescriptor.getter?.let { generatePropertyAccessor(it, fieldSymbol) }
             ?.apply { parent = propertyParent }
@@ -356,7 +346,11 @@ interface IrBuilderExtension {
         }
     }
 
-    fun IrFunction.createParameterDeclarations(receiver: IrValueParameter?, overwriteValueParameters: Boolean = false) {
+    fun IrFunction.createParameterDeclarations(
+        receiver: IrValueParameter?,
+        overwriteValueParameters: Boolean = false,
+        copyTypeParameters: Boolean = true
+    ) {
         fun ParameterDescriptor.irValueParameter() = IrValueParameterImpl(
             this@createParameterDeclarations.startOffset, this@createParameterDeclarations.endOffset,
             SERIALIZABLE_PLUGIN_ORIGIN,
@@ -377,7 +371,7 @@ interface IrBuilderExtension {
         valueParameters.addAll(descriptor.valueParameters.map { it.irValueParameter() })
 
         assert(typeParameters.isEmpty())
-        copyTypeParamsFromDescriptor()
+        if (copyTypeParameters) copyTypeParamsFromDescriptor()
     }
 
     fun IrFunction.copyTypeParamsFromDescriptor() {

plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/backend/ir/SerializerIrGenerator.kt

@@ -9,10 +9,7 @@ import org.jetbrains.kotlin.backend.common.BackendContext
 import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
 import org.jetbrains.kotlin.backend.common.lower.irIfThen
 import org.jetbrains.kotlin.backend.common.lower.irThrow
-import org.jetbrains.kotlin.descriptors.ClassConstructorDescriptor
+import org.jetbrains.kotlin.descriptors.*
-import org.jetbrains.kotlin.descriptors.ClassDescriptor
-import org.jetbrains.kotlin.descriptors.FunctionDescriptor
-import org.jetbrains.kotlin.descriptors.PropertyDescriptor
 import org.jetbrains.kotlin.ir.builders.*
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
@@ -30,7 +27,6 @@ import org.jetbrains.kotlinx.serialization.compiler.backend.common.getSerialType
 import org.jetbrains.kotlinx.serialization.compiler.resolve.*
 import org.jetbrains.kotlinx.serialization.compiler.resolve.SerialEntityNames.DECODER_CLASS
 import org.jetbrains.kotlinx.serialization.compiler.resolve.SerialEntityNames.ENCODER_CLASS
-import org.jetbrains.kotlinx.serialization.compiler.resolve.SerialEntityNames.KSERIALIZER_NAME
 import org.jetbrains.kotlinx.serialization.compiler.resolve.SerialEntityNames.SERIAL_DESCRIPTOR_CLASS_IMPL
 import org.jetbrains.kotlinx.serialization.compiler.resolve.SerialEntityNames.STRUCTURE_DECODER_CLASS
 import org.jetbrains.kotlinx.serialization.compiler.resolve.SerialEntityNames.STRUCTURE_ENCODER_CLASS
@@ -153,7 +149,7 @@ class SerializerIrGenerator(val irClass: IrClass, override val compilerContext:
                 compilerContext.irBuiltIns.unitType,
                 primaryCtor.symbol
             ).apply {
-                ctor.typeParameters.forEachIndexed { index, irTypeParameter ->
+                irClass.typeParameters.forEachIndexed { index, irTypeParameter ->
                     putTypeArgument(index, irTypeParameter.defaultType)
                 }
             }
@@ -171,7 +167,7 @@ class SerializerIrGenerator(val irClass: IrClass, override val compilerContext:
 
         }
 
-    override fun generateChildSerializersGetter(function: FunctionDescriptor) = irClass.contributeFunction(function) { irFun ->
+    override fun generateChildSerializersGetter(function: FunctionDescriptor) = irClass.contributeFunction(function, fromStubs = true) { irFun ->
         val allSerializers = serializableProperties.map { requireNotNull(
                 serializerTower(this@SerializerIrGenerator, irFun.dispatchReceiverParameter!!, it)) { "Property ${it.name} must have a serializer" }
         }
@@ -188,7 +184,7 @@ class SerializerIrGenerator(val irClass: IrClass, override val compilerContext:
     fun ClassDescriptor.referenceMethod(methodName: String) =
         getFuncDesc(methodName).single().let { compilerContext.externalSymbols.referenceFunction(it) }
 
-    override fun generateSave(function: FunctionDescriptor) = irClass.contributeFunction(function) { saveFunc ->
+    override fun generateSave(function: FunctionDescriptor) = irClass.contributeFunction(function, fromStubs = true) { saveFunc ->
 
         val fieldInitializer: (SerializableProperty) -> IrExpression? =
             buildInitializersRemapping(serializableIrClass).run { { invoke(it.irField) } }
@@ -306,7 +302,7 @@ class SerializerIrGenerator(val irClass: IrClass, override val compilerContext:
             defaultPrimitive to kType
     }
 
-    override fun generateLoad(function: FunctionDescriptor) = irClass.contributeFunction(function) { loadFunc ->
+    override fun generateLoad(function: FunctionDescriptor) = irClass.contributeFunction(function, fromStubs = true) { loadFunc ->
         fun irThis(): IrExpression =
             IrGetValueImpl(startOffset, endOffset, loadFunc.dispatchReceiverParameter!!.symbol)
 
@@ -436,7 +432,12 @@ class SerializerIrGenerator(val irClass: IrClass, override val compilerContext:
             compilerContext.externalSymbols.referenceConstructor(serializableDescriptor.unsubstitutedPrimaryConstructor!!)
         }
 
-        +irReturn(irInvoke(null, ctor, typeArgs, args))
+        // todo: throw UnsupportedOperationException when feature branch with `open SerializerGenerator` (enums) will be merged
+        if (serializableDescriptor.modality != Modality.ABSTRACT && serializableDescriptor.modality != Modality.SEALED) {
+            +irReturn(irInvoke(null, ctor, typeArgs, args))
+        } else {
+            +irThrowNpe()
+        }
     }
 
     companion object {

plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/backend/jvm/JVMCodegenUtil.kt

@@ -29,10 +29,7 @@ import org.jetbrains.kotlin.resolve.jvm.diagnostics.OtherOrigin
 import org.jetbrains.kotlin.resolve.jvm.jvmSignature.JvmMethodSignature
 import org.jetbrains.kotlin.types.KotlinType
 import org.jetbrains.kotlin.types.typeUtil.isTypeParameter
-import org.jetbrains.kotlinx.serialization.compiler.backend.common.AbstractSerialGenerator
+import org.jetbrains.kotlinx.serialization.compiler.backend.common.*
-import org.jetbrains.kotlinx.serialization.compiler.backend.common.SerialTypeInfo
-import org.jetbrains.kotlinx.serialization.compiler.backend.common.findAddOnSerializer
-import org.jetbrains.kotlinx.serialization.compiler.backend.common.findTypeSerializerOrContext
 import org.jetbrains.kotlinx.serialization.compiler.resolve.*
 import org.jetbrains.kotlinx.serialization.compiler.resolve.SerialEntityNames.DECODER_CLASS
 import org.jetbrains.kotlinx.serialization.compiler.resolve.SerialEntityNames.ENCODER_CLASS
@@ -220,7 +217,7 @@ internal fun InstructionAdapter.stackValueSerializerInstanceFromSerializer(codeg
 // use iv == null to check only (do not emit serializer onto stack)
 internal fun AbstractSerialGenerator.stackValueSerializerInstance(codegen: ClassBodyCodegen, module: ModuleDescriptor, kType: KotlinType, maybeSerializer: ClassDescriptor?,
                                           iv: InstructionAdapter?, genericIndex: Int? = null, genericSerializerFieldGetter: (InstructionAdapter.(Int) -> Unit)? = null): Boolean {
-    if (genericIndex != null) {
+    if (maybeSerializer == null && genericIndex != null) {
         // get field from serializer object
         iv?.run { genericSerializerFieldGetter?.invoke(this, genericIndex) }
         return true

plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/resolve/KSerializationUtil.kt

@@ -28,10 +28,9 @@ import org.jetbrains.kotlin.resolve.descriptorUtil.module
 import org.jetbrains.kotlin.resolve.lazy.descriptors.LazyAnnotationDescriptor
 import org.jetbrains.kotlin.resolve.scopes.getDescriptorsFiltered
 import org.jetbrains.kotlin.types.*
-import org.jetbrains.kotlin.types.typeUtil.isSubtypeOf
+import org.jetbrains.kotlin.types.typeUtil.*
-import org.jetbrains.kotlinx.serialization.compiler.backend.jvm.contextSerializerId
+import org.jetbrains.kotlinx.serialization.compiler.backend.jvm.*
-import org.jetbrains.kotlinx.serialization.compiler.backend.jvm.enumSerializerId
+import org.jetbrains.kotlinx.serialization.compiler.resolve.SerialEntityNames.KSERIALIZER_CLASS
-import org.jetbrains.kotlinx.serialization.compiler.backend.jvm.polymorphicSerializerId
 import org.jetbrains.kotlinx.serialization.compiler.resolve.SerializationAnnotations.serialInfoFqName
 
 internal fun isAllowedToHaveAutoGeneratedSerializerMethods(
@@ -97,7 +96,13 @@ internal val Annotations.serialTransient: Boolean
 
 val KotlinType?.toClassDescriptor: ClassDescriptor?
     @JvmName("toClassDescriptor")
-    get() = this?.constructor?.declarationDescriptor as? ClassDescriptor
+    get() = this?.constructor?.declarationDescriptor?.let { descriptor ->
+        when(descriptor) {
+            is ClassDescriptor -> descriptor
+            is TypeParameterDescriptor -> descriptor.representativeUpperBound.toClassDescriptor
+            else -> null
+        }
+    }
 
 internal val ClassDescriptor.shouldHaveGeneratedMethodsInCompanion: Boolean
     get() = this.kind == ClassKind.CLASS && annotations.hasAnnotation(SerializationAnnotations.serializableAnnotationFqName)

plugins/kotlin-serialization/kotlin-serialization-compiler/testData/codegen/Basic.ir.txt

@@ -188,10 +188,8 @@ public final class ListOfUsers$$serializer : java/lang/Object, kotlinx/serializa
           ALOAD (4)
           ALOAD (3)
           INVOKEINTERFACE (kotlinx/serialization/CompositeEncoder, endStructure, (Lkotlinx/serialization/SerialDescriptor;)V)
-        LABEL (L2)
-        LINENUMBER (13)
           RETURN
-        LABEL (L3)
+        LABEL (L2)
     }
 
     public void serialize(kotlinx.serialization.Encoder encoder, java.lang.Object obj) {
@@ -493,10 +491,8 @@ public final class OptionalUser$$serializer : java/lang/Object, kotlinx/serializ
           ALOAD (4)
           ALOAD (3)
           INVOKEINTERFACE (kotlinx/serialization/CompositeEncoder, endStructure, (Lkotlinx/serialization/SerialDescriptor;)V)
-        LABEL (L7)
-        LINENUMBER (10)
           RETURN
-        LABEL (L8)
+        LABEL (L7)
     }
 
     public void serialize(kotlinx.serialization.Encoder encoder, java.lang.Object obj) {
@@ -840,10 +836,8 @@ public final class User$$serializer : java/lang/Object, kotlinx/serialization/in
           ALOAD (4)
           ALOAD (3)
           INVOKEINTERFACE (kotlinx/serialization/CompositeEncoder, endStructure, (Lkotlinx/serialization/SerialDescriptor;)V)
-        LABEL (L2)
-        LINENUMBER (7)
           RETURN
-        LABEL (L3)
+        LABEL (L2)
     }
 
     public void serialize(kotlinx.serialization.Encoder encoder, java.lang.Object obj) {