Support mapping for inline classes based on type variables

core/descriptors.jvm/src/org/jetbrains/kotlin/load/kotlin/typeSignatureMapping.kt

@@ -19,7 +19,8 @@ import org.jetbrains.kotlin.resolve.DescriptorUtils
 import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameUnsafe
 import org.jetbrains.kotlin.resolve.jvm.JvmClassName
 import org.jetbrains.kotlin.resolve.jvm.JvmPrimitiveType
-import org.jetbrains.kotlin.resolve.underlyingRepresentation
+import org.jetbrains.kotlin.resolve.substitutedUnderlyingType
+import org.jetbrains.kotlin.resolve.unsubstitutedUnderlyingType
 import org.jetbrains.kotlin.types.*
 import org.jetbrains.kotlin.types.typeUtil.replaceArgumentsWithStarProjections
 import org.jetbrains.kotlin.utils.DO_NOTHING_3
@@ -130,15 +131,9 @@ fun <T : Any> mapType(
 
         descriptor is ClassDescriptor -> {
             if (descriptor.isInline && !mode.needInlineClassWrapping) {
-                val underlyingType = descriptor.underlyingRepresentation()?.type
-                if (underlyingType != null) {
-                    if (!kotlinType.isMarkedNullable) {
-                        return mapType(underlyingType, factory, mode, typeMappingConfiguration, descriptorTypeWriter, writeGenericType)
-                    }
-
-                    if (!underlyingType.isMarkedNullable && !KotlinBuiltIns.isPrimitiveType(underlyingType)) {
-                        return mapType(underlyingType, factory, mode, typeMappingConfiguration, descriptorTypeWriter, writeGenericType)
-                    }
+                val typeForMapping = computeUnderlyingType(kotlinType)
+                if (typeForMapping != null) {
+                    return mapType(typeForMapping, factory, mode, typeMappingConfiguration, descriptorTypeWriter, writeGenericType)
                 }
             }
 
@@ -214,6 +209,23 @@ private fun <T : Any> mapBuiltInType(type: KotlinType, typeFactory: JvmTypeFacto
     return null
 }
 
+private fun computeUnderlyingType(inlineClassType: KotlinType): KotlinType? {
+    if (!shouldUseUnderlyingType(inlineClassType)) return null
+
+    val descriptor = inlineClassType.unsubstitutedUnderlyingType()?.constructor?.declarationDescriptor ?: return null
+    return if (descriptor is TypeParameterDescriptor)
+        getRepresentativeUpperBound(descriptor)
+    else
+        inlineClassType.substitutedUnderlyingType()
+}
+
+private fun shouldUseUnderlyingType(inlineClassType: KotlinType): Boolean {
+    val underlyingType = inlineClassType.unsubstitutedUnderlyingType() ?: return false
+
+    return !inlineClassType.isMarkedNullable ||
+            !TypeUtils.isNullableType(underlyingType) && !KotlinBuiltIns.isPrimitiveType(underlyingType)
+}
+
 fun computeInternalName(
     klass: ClassDescriptor,
     typeMappingConfiguration: TypeMappingConfiguration<*> = TypeMappingConfigurationImpl

core/descriptors/src/org/jetbrains/kotlin/resolve/inlineClassesUtils.kt

@@ -8,6 +8,7 @@ package org.jetbrains.kotlin.resolve
 import org.jetbrains.kotlin.descriptors.ClassDescriptor
 import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
 import org.jetbrains.kotlin.descriptors.ValueParameterDescriptor
+import org.jetbrains.kotlin.incremental.components.NoLookupLocation
 import org.jetbrains.kotlin.types.KotlinType
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
@@ -18,8 +19,15 @@ fun ClassDescriptor.underlyingRepresentation(): ValueParameterDescriptor? {
 
 fun DeclarationDescriptor.isInlineClass() = this is ClassDescriptor && this.isInline
 
-fun KotlinType.underlyingTypeOfInlineClassType(): KotlinType? {
-    return constructor.declarationDescriptor.safeAs<ClassDescriptor>()?.underlyingRepresentation()?.type
+fun KotlinType.unsubstitutedUnderlyingParameter(): ValueParameterDescriptor? {
+    return constructor.declarationDescriptor.safeAs<ClassDescriptor>()?.underlyingRepresentation()
 }
 
-fun KotlinType.isInlineClassType(): Boolean = constructor.declarationDescriptor?.isInlineClass() ?: false
+fun KotlinType.unsubstitutedUnderlyingType(): KotlinType? = unsubstitutedUnderlyingParameter()?.type
+
+fun KotlinType.isInlineClassType(): Boolean = constructor.declarationDescriptor?.isInlineClass() ?: false
+
+fun KotlinType.substitutedUnderlyingType(): KotlinType? {
+    val parameter = unsubstitutedUnderlyingParameter() ?: return null
+    return memberScope.getContributedVariables(parameter.name, NoLookupLocation.FOR_ALREADY_TRACKED).singleOrNull()?.type
+}