Do not create additional module for built-ins in reflection

core/descriptors.runtime/src/kotlin/reflect/jvm/internal/components/ReflectKotlinClassFinder.kt

@@ -16,11 +16,13 @@
 
 package kotlin.reflect.jvm.internal.components
 
+import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.load.java.structure.JavaClass
 import org.jetbrains.kotlin.load.kotlin.KotlinClassFinder
 import org.jetbrains.kotlin.load.kotlin.KotlinClassFinder.Result.KotlinClass
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.serialization.deserialization.builtins.BuiltInSerializerProtocol
 import java.io.InputStream
 
 class ReflectKotlinClassFinder(private val classLoader: ClassLoader) : KotlinClassFinder {
@@ -41,8 +43,11 @@ class ReflectKotlinClassFinder(private val classLoader: ClassLoader) : KotlinCla
     // TODO
     override fun hasMetadataPackage(fqName: FqName): Boolean = false
 
-    // TODO: load built-ins from classLoader
-    override fun findBuiltInsData(packageFqName: FqName): InputStream? = null
+    override fun findBuiltInsData(packageFqName: FqName): InputStream? {
+        if (!packageFqName.startsWith(KotlinBuiltIns.BUILT_INS_PACKAGE_NAME)) return null
+
+        return classLoader.getResourceAsStream(BuiltInSerializerProtocol.getBuiltInsFilePath(packageFqName))
+    }
 }
 
 private fun ClassId.toRuntimeFqName(): String {

core/descriptors.runtime/src/kotlin/reflect/jvm/internal/components/RuntimeModuleData.kt

@@ -18,9 +18,11 @@ package kotlin.reflect.jvm.internal.components
 
 import org.jetbrains.kotlin.builtins.ReflectionTypes
 import org.jetbrains.kotlin.builtins.jvm.JvmBuiltIns
+import org.jetbrains.kotlin.builtins.jvm.JvmBuiltInsPackageFragmentProvider
 import org.jetbrains.kotlin.descriptors.ModuleDescriptor
 import org.jetbrains.kotlin.descriptors.NotFoundClasses
 import org.jetbrains.kotlin.descriptors.SupertypeLoopChecker
+import org.jetbrains.kotlin.descriptors.impl.CompositePackageFragmentProvider
 import org.jetbrains.kotlin.descriptors.impl.ModuleDescriptorImpl
 import org.jetbrains.kotlin.incremental.components.LookupTracker
 import org.jetbrains.kotlin.load.java.AnnotationTypeQualifierResolver
@@ -55,8 +57,9 @@ class RuntimeModuleData private constructor(
     companion object {
         fun create(classLoader: ClassLoader): RuntimeModuleData {
             val storageManager = LockBasedStorageManager("RuntimeModuleData")
-            val builtIns = JvmBuiltIns(storageManager)
+            val builtIns = JvmBuiltIns(storageManager, false)
             val module = ModuleDescriptorImpl(Name.special("<runtime module for $classLoader>"), storageManager, builtIns)
+            builtIns.builtInsModule = module
 
             val reflectKotlinClassFinder = ReflectKotlinClassFinder(classLoader)
             val deserializedDescriptorResolver = DeserializedDescriptorResolver()
@@ -89,12 +92,16 @@ class RuntimeModuleData private constructor(
                 binaryClassAnnotationAndConstantLoader, lazyJavaPackageFragmentProvider, notFoundClasses,
                 RuntimeErrorReporter, LookupTracker.DO_NOTHING, ContractDeserializer.DEFAULT
             )
+            val builtinsProvider = JvmBuiltInsPackageFragmentProvider(
+                    storageManager, reflectKotlinClassFinder, module, notFoundClasses, builtIns.settings, builtIns.settings,
+                    DeserializationConfiguration.Default
+            )
 
             singleModuleClassResolver.resolver = javaDescriptorResolver
             deserializedDescriptorResolver.setComponents(deserializationComponentsForJava)
 
-            module.setDependencies(module, builtIns.builtInsModule)
-            module.initialize(javaDescriptorResolver.packageFragmentProvider)
+            module.setDependencies(module)
+            module.initialize(CompositePackageFragmentProvider(listOf(javaDescriptorResolver.packageFragmentProvider, builtinsProvider)))
 
             return RuntimeModuleData(deserializationComponentsForJava.components, runtimePackagePartProvider)
         }