JVM IR: Create package private synthetic multi file part classes

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrUtils.kt

@@ -393,7 +393,7 @@ val IrDeclaration.isTopLevel: Boolean
     get() {
         if (parent is IrPackageFragment) return true
         val parentClass = parent as? IrClass
-        return parentClass?.origin == IrDeclarationOrigin.FILE_CLASS && parentClass.parent is IrPackageFragment
+        return parentClass?.isFileClass == true && parentClass.parent is IrPackageFragment
     }
 
 fun Scope.createTemporaryVariableWithWrappedDescriptor(

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/SingleAbstractMethodLowering.kt

@@ -65,7 +65,7 @@ abstract class SingleAbstractMethodLowering(val context: CommonBackendContext) :
     abstract fun getSuperTypeForWrapper(typeOperand: IrType): IrType
 
     override fun lower(irFile: IrFile) {
-        enclosingContainer = irFile.declarations.filterIsInstance<IrClass>().find { it.origin == IrDeclarationOrigin.FILE_CLASS }
+        enclosingContainer = irFile.declarations.filterIsInstance<IrClass>().find { it.isFileClass }
             ?: irFile
         irFile.transformChildrenVoid()
 

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/ClassCodegen.kt

@@ -266,7 +266,7 @@ open class ClassCodegen protected constructor(
                 val entry = irClass.fileParent.fileEntry
                 if (entry is MultifileFacadeFileEntry) {
                     val partInternalNames = entry.partFiles.mapNotNull { partFile ->
-                        val fileClass = partFile.declarations.singleOrNull { it.origin == IrDeclarationOrigin.FILE_CLASS } as IrClass?
+                        val fileClass = partFile.declarations.singleOrNull { it.isFileClass } as IrClass?
                         if (fileClass != null) typeMapper.mapClass(fileClass).internalName else null
                     }
                     MultifileClassCodegenImpl.writeMetadata(

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/intrinsics/IrIntrinsicMethods.kt

@@ -28,6 +28,7 @@ import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
 import org.jetbrains.kotlin.ir.types.classOrNull
 import org.jetbrains.kotlin.ir.types.classifierOrNull
 import org.jetbrains.kotlin.ir.util.fqNameWhenAvailable
+import org.jetbrains.kotlin.ir.util.isFileClass
 import org.jetbrains.kotlin.lexer.KtSingleValueToken
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.name.FqName
@@ -209,7 +210,7 @@ class IrIntrinsicMethods(val irBuiltIns: IrBuiltIns, val symbols: JvmSymbols) {
         private fun IrFunctionSymbol.toKey(): Key? {
             val parent = owner.parent
             val ownerFqName = when {
-                parent is IrClass && parent.origin == IrDeclarationOrigin.FILE_CLASS ->
+                parent is IrClass && parent.isFileClass ->
                     (parent.parent as IrPackageFragment).fqName
                 parent is IrClass -> parent.fqNameWhenAvailable ?: return null
                 parent is IrPackageFragment -> parent.fqName

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/CallableReferenceLowering.kt

@@ -374,7 +374,7 @@ internal class CallableReferenceLowering(private val context: JvmBackendContext)
             // The non-IR backend generates equally meaningless "kotlin/KotlinPackage" in this case (see KT-17151).
             val kClass = kClassReference((irContainer as? IrClass)?.defaultType ?: context.irBuiltIns.anyNType)
 
-            if ((irContainer as? IrClass)?.origin != IrDeclarationOrigin.FILE_CLASS && irContainer !is IrPackageFragment)
+            if ((irContainer as? IrClass)?.isFileClass != true && irContainer !is IrPackageFragment)
                 return kClass
 
             return irCall(context.ir.symbols.getOrCreateKotlinPackage).apply {

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/FileClassLowering.kt

@@ -28,6 +28,7 @@ import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.fileClasses.JvmFileClassInfo
 import org.jetbrains.kotlin.fileClasses.JvmFileClassUtil
 import org.jetbrains.kotlin.fileClasses.JvmSimpleFileClassInfo
+import org.jetbrains.kotlin.ir.builders.declarations.buildClass
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.declarations.impl.IrClassImpl
 import org.jetbrains.kotlin.ir.descriptors.WrappedClassDescriptor
@@ -96,11 +97,11 @@ private class FileClassLowering(val context: JvmBackendContext) : FileLoweringPa
         }
         return IrClassImpl(
             0, fileEntry.maxOffset,
-            IrDeclarationOrigin.FILE_CLASS,
+            if (!fileClassInfo.withJvmMultifileClass) IrDeclarationOrigin.FILE_CLASS else IrDeclarationOrigin.MULTIFILE_PART_CLASS,
             symbol = IrClassSymbolImpl(descriptor),
             name = fileClassInfo.fileClassFqName.shortName(),
             kind = ClassKind.CLASS,
-            visibility = Visibilities.PUBLIC,
+            visibility = if (!fileClassInfo.withJvmMultifileClass) Visibilities.PUBLIC else Visibilities.PRIVATE,
             modality = Modality.FINAL,
             isCompanion = false,
             isInner = false,

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/MainMethodGenerationLowering.kt

@@ -26,6 +26,7 @@ import org.jetbrains.kotlin.ir.declarations.IrDeclarationOrigin
 import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.util.functions
+import org.jetbrains.kotlin.ir.util.isFileClass
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.types.Variance
 
@@ -40,7 +41,7 @@ internal class MainMethodGenerationLowering(val context: JvmBackendContext) : Cl
 
     override fun lower(irClass: IrClass) {
         if (!context.configuration.languageVersionSettings.supportsFeature(LanguageFeature.ExtendedMainConvention)) return
-        if (irClass.origin != IrDeclarationOrigin.FILE_CLASS) return
+        if (!irClass.isFileClass) return
 
         val parameterlessMain = irClass.functions.find { it.isParameterlessMainMethod() } ?: return
 

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/IrDeclarationOrigin.kt

@@ -37,6 +37,7 @@ interface IrDeclarationOrigin {
     object MOVED_EXTENSION_RECEIVER : IrDeclarationOriginImpl("MOVED_EXTENSION_RECEIVER")
 
     object FILE_CLASS : IrDeclarationOriginImpl("FILE_CLASS")
+    object MULTIFILE_PART_CLASS : IrDeclarationOriginImpl("MULTIFILE_PART_CLASS", isSynthetic = true)
     object GENERATED_DATA_CLASS_MEMBER : IrDeclarationOriginImpl("GENERATED_DATA_CLASS_MEMBER")
     object GENERATED_INLINE_CLASS_MEMBER : IrDeclarationOriginImpl("GENERATED_INLINE_CLASS_MEMBER")
     object LOCAL_FUNCTION_FOR_LAMBDA : IrDeclarationOriginImpl("LOCAL_FUNCTION_FOR_LAMBDA")

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/descriptors/WrappedDescriptors.kt

@@ -1069,7 +1069,7 @@ open class WrappedFieldDescriptor(
 private fun getContainingDeclaration(declaration: IrDeclarationWithName): DeclarationDescriptor {
     val parent = declaration.parent
     val parentDescriptor = (parent as IrSymbolOwner).symbol.descriptor
-    return if (parent is IrClass && parent.origin == IrDeclarationOrigin.FILE_CLASS) {
+    return if (parent is IrClass && parent.isFileClass) {
         // JVM IR adds facade classes for IR of functions/properties loaded both from sources and dependencies. However, these shouldn't
         // exist in the descriptor hierarchy, since this is what the old backend (dealing with descriptors) expects.
         parentDescriptor.containingDeclaration!!

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/IrUtils.kt

@@ -670,3 +670,6 @@ fun SymbolTable.findOrDeclareExternalPackageFragment(descriptor: PackageFragment
             declareExternalPackageFragment(descriptor)
         }
     }.owner
+
+val IrDeclaration.isFileClass: Boolean
+    get() = origin == IrDeclarationOrigin.FILE_CLASS || origin == IrDeclarationOrigin.MULTIFILE_PART_CLASS

compiler/testData/codegen/bytecodeText/superFlagInMultiFileFacade.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 @file:kotlin.jvm.JvmMultifileClass
 @file:kotlin.jvm.JvmName("Test")