[IR] Make isExternal mutable and accessible via common interface

JS IR: Mark all effectively external declarations as external to access it
directly instead of computing it every time

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/lazy/AbstractFir2IrLazyFunction.kt

@@ -53,8 +53,9 @@ abstract class AbstractFir2IrLazyFunction<F : FirMemberDeclaration>(
     override val isInline: Boolean
         get() = fir.isInline
 
-    override val isExternal: Boolean
+    override var isExternal: Boolean by lazyVar {
-        get() = fir.isExternal
+        fir.isExternal
+    }
 
     override val isExpect: Boolean
         get() = fir.isExpect

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/lazy/Fir2IrLazyClass.kt

@@ -84,8 +84,11 @@ class Fir2IrLazyClass(
     override val isData: Boolean
         get() = fir.isData
 
-    override val isExternal: Boolean
+    override var isExternal: Boolean
         get() = fir.isExternal
+        set(_) {
+            error("Mutating Fir2Ir lazy elements is not possible")
+        }
 
     override val isInline: Boolean
         get() = fir.isInline

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/lazy/Fir2IrLazyConstructor.kt

@@ -50,8 +50,11 @@ class Fir2IrLazyConstructor(
     override val isInline: Boolean
         get() = fir.isInline
 
-    override val isExternal: Boolean
+    override var isExternal: Boolean
         get() = fir.isExternal
+        set(_) {
+            error("Mutating Fir2Ir lazy elements is not possible")
+        }
 
     override val isExpect: Boolean
         get() = fir.isExpect

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/lazy/Fir2IrLazyProperty.kt

@@ -63,8 +63,11 @@ class Fir2IrLazyProperty(
     override val isDelegated: Boolean
         get() = fir.delegate != null
 
-    override val isExternal: Boolean
+    override var isExternal: Boolean
         get() = fir.isExternal
+        set(_) {
+            error("Mutating Fir2Ir lazy elements is not possible")
+        }
 
     override val isExpect: Boolean
         get() = fir.isExpect

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/MoveBodilessDeclarationsToSeparatePlace.kt

@@ -48,6 +48,7 @@ private fun isBuiltInClass(declaration: IrDeclaration): Boolean =
 fun moveBodilessDeclarationsToSeparatePlace(context: JsIrBackendContext, moduleFragment: IrModuleFragment) {
     MoveBodilessDeclarationsToSeparatePlaceLowering(context).let { moveBodiless ->
         moduleFragment.files.forEach {
+            markExternalDeclarations(it)
             moveBodiless.lower(it)
         }
     }
@@ -112,3 +113,31 @@ class MoveBodilessDeclarationsToSeparatePlaceLowering(private val context: JsIrB
         }, null)
     }
 }
+
+fun markExternalDeclarations(packageFragment: IrPackageFragment) {
+    for (declaration in packageFragment.declarations) {
+        if (declaration is IrPossiblyExternalDeclaration) {
+            if (declaration.isExternal) {
+                markNestedExternalDeclarations(declaration)
+            }
+        }
+    }
+}
+
+
+fun markNestedExternalDeclarations(declaration: IrDeclaration) {
+    if (declaration is IrPossiblyExternalDeclaration) {
+        declaration.isExternal = true
+    }
+    if (declaration is IrProperty) {
+        declaration.getter?.isExternal = true
+        declaration.setter?.isExternal = true
+        declaration.backingField?.isExternal = true
+    }
+    if (declaration is IrClass) {
+        declaration.declarations.forEach {
+            markNestedExternalDeclarations(it)
+        }
+    }
+}
+

compiler/ir/ir.tree.impl/src/org/jetbrains/kotlin/ir/declarations/impl/IrClassImpl.kt

@@ -36,7 +36,7 @@ class IrClassImpl(
     override val isCompanion: Boolean = false,
     override val isInner: Boolean = false,
     override val isData: Boolean = false,
-    override val isExternal: Boolean = false,
+    override var isExternal: Boolean = false,
     override val isInline: Boolean = false,
     override val isExpect: Boolean = false,
     override val isFun: Boolean = false,

compiler/ir/ir.tree.impl/src/org/jetbrains/kotlin/ir/declarations/impl/IrConstructorImpl.kt

@@ -38,7 +38,7 @@ class IrConstructorImpl(
     override var visibility: DescriptorVisibility,
     returnType: IrType,
     override val isInline: Boolean,
-    override val isExternal: Boolean,
+    override var isExternal: Boolean,
     override val isPrimary: Boolean,
     override val isExpect: Boolean,
     override val containerSource: DeserializedContainerSource? = null,

compiler/ir/ir.tree.impl/src/org/jetbrains/kotlin/ir/declarations/impl/IrFieldImpl.kt

@@ -36,7 +36,7 @@ class IrFieldImpl(
     override var type: IrType,
     override var visibility: DescriptorVisibility,
     override val isFinal: Boolean,
-    override val isExternal: Boolean,
+    override var isExternal: Boolean,
     override val isStatic: Boolean,
 ) : IrField() {
     init {

compiler/ir/ir.tree.impl/src/org/jetbrains/kotlin/ir/declarations/impl/IrFunctionImpl.kt

@@ -29,7 +29,7 @@ abstract class IrFunctionCommonImpl(
     override var visibility: DescriptorVisibility,
     returnType: IrType,
     override val isInline: Boolean,
-    override val isExternal: Boolean,
+    override var isExternal: Boolean,
     override val isTailrec: Boolean,
     override val isSuspend: Boolean,
     override val isOperator: Boolean,

compiler/ir/ir.tree.impl/src/org/jetbrains/kotlin/ir/declarations/impl/IrPropertyImpl.kt

@@ -37,7 +37,7 @@ abstract class IrPropertyCommonImpl(
     override val isConst: Boolean,
     override val isLateinit: Boolean,
     override val isDelegated: Boolean,
-    override val isExternal: Boolean,
+    override var isExternal: Boolean,
     override val isExpect: Boolean,
     override val containerSource: DeserializedContainerSource?,
 ) : IrProperty() {

compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/declarations/persistent/PersistentIrClass.kt

@@ -39,7 +39,7 @@ internal class PersistentIrClass(
     override val isCompanion: Boolean = false,
     override val isInner: Boolean = false,
     override val isData: Boolean = false,
-    override val isExternal: Boolean = false,
+    isExternal: Boolean = false,
     override val isInline: Boolean = false,
     override val isExpect: Boolean = false,
     override val isFun: Boolean = false,
@@ -142,6 +142,16 @@ internal class PersistentIrClass(
             }
         }
 
+    override var isExternalField: Boolean = isExternal
+
+    override var isExternal: Boolean
+        get() = getCarrier().isExternalField
+        set(v) {
+            if (isExternal != v) {
+                setCarrier().isExternalField = v
+            }
+        }
+
     override var attributeOwnerIdField: IrAttributeContainer = this
 
     override var attributeOwnerId: IrAttributeContainer

compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/declarations/persistent/PersistentIrConstructor.kt

@@ -40,7 +40,7 @@ internal class PersistentIrConstructor(
     visibility: DescriptorVisibility,
     returnType: IrType,
     override val isInline: Boolean,
-    override val isExternal: Boolean,
+    isExternal: Boolean,
     override val isPrimary: Boolean,
     override val isExpect: Boolean,
     override val containerSource: DeserializedContainerSource?
@@ -153,6 +153,16 @@ internal class PersistentIrConstructor(
             }
         }
 
+    override var isExternalField: Boolean = isExternal
+
+    override var isExternal: Boolean
+        get() = getCarrier().isExternalField
+        set(v) {
+            if (isExternal != v) {
+                setCarrier().isExternalField = v
+            }
+        }
+
     @ObsoleteDescriptorBasedAPI
     override val descriptor: ClassConstructorDescriptor
         get() = symbol.descriptor

compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/declarations/persistent/PersistentIrField.kt

@@ -38,7 +38,7 @@ internal class PersistentIrField(
     type: IrType,
     override var visibility: DescriptorVisibility,
     override val isFinal: Boolean,
-    override val isExternal: Boolean,
+    isExternal: Boolean,
     override val isStatic: Boolean
 ) : IrField(),
     PersistentIrDeclarationBase<FieldCarrier>,
@@ -104,4 +104,14 @@ internal class PersistentIrField(
                 setCarrier().typeField = v
             }
         }
+
+    override var isExternalField: Boolean = isExternal
+
+    override var isExternal: Boolean
+        get() = getCarrier().isExternalField
+        set(v) {
+            if (isExternal != v) {
+                setCarrier().isExternalField = v
+            }
+        }
 }

compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/declarations/persistent/PersistentIrFunction.kt

@@ -31,7 +31,7 @@ internal abstract class PersistentIrFunctionCommon(
     visibility: DescriptorVisibility,
     returnType: IrType,
     override val isInline: Boolean,
-    override val isExternal: Boolean,
+    isExternal: Boolean,
     override val isTailrec: Boolean,
     override val isSuspend: Boolean,
     override val isOperator: Boolean,
@@ -173,6 +173,16 @@ internal abstract class PersistentIrFunctionCommon(
                 setCarrier().correspondingPropertySymbolField = v
             }
         }
+
+    override var isExternalField: Boolean = isExternal
+
+    override var isExternal: Boolean
+        get() = getCarrier().isExternalField
+        set(v) {
+            if (isExternal != v) {
+                setCarrier().isExternalField = v
+            }
+        }
 }
 
 internal class PersistentIrFunction(

compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/declarations/persistent/PersistentIrProperty.kt

@@ -39,7 +39,7 @@ internal abstract class PersistentIrPropertyCommon(
     override val isConst: Boolean,
     override val isLateinit: Boolean,
     override val isDelegated: Boolean,
-    override val isExternal: Boolean,
+    isExternal: Boolean,
     override val isExpect: Boolean,
     override val containerSource: DeserializedContainerSource?,
 ) : IrProperty(),
@@ -106,6 +106,16 @@ internal abstract class PersistentIrPropertyCommon(
                 setCarrier().attributeOwnerIdField = v
             }
         }
+
+    override var isExternalField: Boolean = isExternal
+
+    override var isExternal: Boolean
+        get() = getCarrier().isExternalField
+        set(v) {
+            if (isExternal != v) {
+                setCarrier().isExternalField = v
+            }
+        }
 }
 
 internal class PersistentIrProperty(

compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/declarations/persistent/carriers/ClassCarrier.kt

@@ -16,6 +16,7 @@ internal interface ClassCarrier : DeclarationCarrier {
     var metadataField: MetadataSource?
     var visibilityField: DescriptorVisibility
     var modalityField: Modality
+    var isExternalField: Boolean
     var attributeOwnerIdField: IrAttributeContainer
     var typeParametersField: List<IrTypeParameter>
     var superTypesField: List<IrType>
@@ -32,7 +33,8 @@ internal interface ClassCarrier : DeclarationCarrier {
             modalityField,
             attributeOwnerIdField,
             typeParametersField,
-            superTypesField
+            superTypesField,
+            isExternalField
         )
     }
 }
@@ -48,5 +50,6 @@ internal class ClassCarrierImpl(
     override var modalityField: Modality,
     override var attributeOwnerIdField: IrAttributeContainer,
     override var typeParametersField: List<IrTypeParameter>,
-    override var superTypesField: List<IrType>
+    override var superTypesField: List<IrType>,
+    override var isExternalField: Boolean
 ) : ClassCarrier

compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/declarations/persistent/carriers/ConstructorCarrier.kt

@@ -25,7 +25,8 @@ internal interface ConstructorCarrier : FunctionBaseCarrier {
             metadataField,
             visibilityField,
             typeParametersField,
-            valueParametersField
+            valueParametersField,
+            isExternalField,
         )
     }
 }
@@ -42,5 +43,6 @@ internal class ConstructorCarrierImpl(
     override var metadataField: MetadataSource?,
     override var visibilityField: DescriptorVisibility,
     override var typeParametersField: List<IrTypeParameter>,
-    override var valueParametersField: List<IrValueParameter>
+    override var valueParametersField: List<IrValueParameter>,
+    override var isExternalField: Boolean,
 ) : ConstructorCarrier

compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/declarations/persistent/carriers/FieldCarrier.kt

@@ -18,6 +18,7 @@ internal interface FieldCarrier : DeclarationCarrier {
     var initializerField: IrExpressionBody?
     var correspondingPropertySymbolField: IrPropertySymbol?
     var metadataField: MetadataSource?
+    var isExternalField: Boolean
 
     override fun clone(): FieldCarrier {
         return FieldCarrierImpl(
@@ -28,7 +29,8 @@ internal interface FieldCarrier : DeclarationCarrier {
             typeField,
             initializerField,
             correspondingPropertySymbolField,
-            metadataField
+            metadataField,
+            isExternalField,
         )
     }
 }
@@ -41,5 +43,6 @@ internal class FieldCarrierImpl(
     override var typeField: IrType,
     override var initializerField: IrExpressionBody?,
     override var correspondingPropertySymbolField: IrPropertySymbol?,
-    override var metadataField: MetadataSource?
+    override var metadataField: MetadataSource?,
+    override var isExternalField: Boolean
 ) : FieldCarrier

compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/declarations/persistent/carriers/FunctionBaseCarrier.kt

@@ -21,4 +21,5 @@ internal interface FunctionBaseCarrier : DeclarationCarrier {
     var visibilityField: DescriptorVisibility
     var typeParametersField: List<IrTypeParameter>
     var valueParametersField: List<IrValueParameter>
+    var isExternalField: Boolean
 }

compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/declarations/persistent/carriers/FunctionCarrier.kt

@@ -34,7 +34,8 @@ internal interface FunctionCarrier : FunctionBaseCarrier {
             valueParametersField,
             correspondingPropertySymbolField,
             overriddenSymbolsField,
-            attributeOwnerIdField
+            attributeOwnerIdField,
+            isExternalField,
         )
     }
 }
@@ -54,5 +55,6 @@ internal class FunctionCarrierImpl(
     override var valueParametersField: List<IrValueParameter>,
     override var correspondingPropertySymbolField: IrPropertySymbol?,
     override var overriddenSymbolsField: List<IrSimpleFunctionSymbol>,
-    override var attributeOwnerIdField: IrAttributeContainer
+    override var attributeOwnerIdField: IrAttributeContainer,
+    override var isExternalField: Boolean,
 ) : FunctionCarrier

compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/declarations/persistent/carriers/PropertyCarrier.kt

@@ -14,6 +14,7 @@ internal interface PropertyCarrier : DeclarationCarrier {
     var setterField: IrSimpleFunction?
     var metadataField: MetadataSource?
     var attributeOwnerIdField: IrAttributeContainer
+    var isExternalField: Boolean
 
     override fun clone(): PropertyCarrier {
         return PropertyCarrierImpl(
@@ -26,6 +27,7 @@ internal interface PropertyCarrier : DeclarationCarrier {
             setterField,
             metadataField,
             attributeOwnerIdField,
+            isExternalField,
         )
     }
 }
@@ -39,5 +41,6 @@ internal class PropertyCarrierImpl(
     override var getterField: IrSimpleFunction?,
     override var setterField: IrSimpleFunction?,
     override var metadataField: MetadataSource?,
-    override var attributeOwnerIdField: IrAttributeContainer
+    override var attributeOwnerIdField: IrAttributeContainer,
+    override var isExternalField: Boolean
 ) : PropertyCarrier

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

@@ -29,7 +29,7 @@ import org.jetbrains.kotlin.ir.visitors.IrElementTransformer
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
 
 abstract class IrClass :
-    IrDeclarationBase(), IrDeclarationWithName, IrDeclarationWithVisibility,
+    IrDeclarationBase(), IrPossiblyExternalDeclaration, IrDeclarationWithVisibility,
     IrDeclarationContainer, IrTypeParametersContainer, IrAttributeContainer, IrMetadataSourceOwner {
 
     @ObsoleteDescriptorBasedAPI
@@ -41,7 +41,6 @@ abstract class IrClass :
     abstract val isCompanion: Boolean
     abstract val isInner: Boolean
     abstract val isData: Boolean
-    abstract val isExternal: Boolean
     abstract val isInline: Boolean
     abstract val isExpect: Boolean
     abstract val isFun: Boolean

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

@@ -17,8 +17,8 @@
 package org.jetbrains.kotlin.ir.declarations
 
 import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
-import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.descriptors.DescriptorVisibility
+import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.IrElementBase
 import org.jetbrains.kotlin.ir.IrStatement
@@ -60,6 +60,10 @@ interface IrDeclarationWithName : IrDeclaration {
     val name: Name
 }
 
+interface IrPossiblyExternalDeclaration : IrDeclarationWithName {
+    var isExternal: Boolean
+}
+
 interface IrOverridableMember : IrDeclarationWithVisibility, IrDeclarationWithName, IrSymbolOwner {
     val modality: Modality
 }

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

@@ -16,7 +16,7 @@ import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
 
 abstract class IrField :
     IrDeclarationBase(),
-    IrDeclarationWithName, IrDeclarationWithVisibility, IrDeclarationParent, IrMetadataSourceOwner {
+    IrPossiblyExternalDeclaration, IrDeclarationWithVisibility, IrDeclarationParent, IrMetadataSourceOwner {
 
     @ObsoleteDescriptorBasedAPI
     abstract override val descriptor: PropertyDescriptor
@@ -24,7 +24,6 @@ abstract class IrField :
 
     abstract var type: IrType
     abstract val isFinal: Boolean
-    abstract val isExternal: Boolean
     abstract val isStatic: Boolean
 
     abstract var initializer: IrExpressionBody?

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

@@ -29,7 +29,7 @@ import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
 
 abstract class IrFunction :
     IrDeclarationBase(),
-    IrDeclarationWithName, IrDeclarationWithVisibility, IrTypeParametersContainer, IrSymbolOwner, IrDeclarationParent, IrReturnTarget,
+    IrPossiblyExternalDeclaration, IrDeclarationWithVisibility, IrTypeParametersContainer, IrSymbolOwner, IrDeclarationParent, IrReturnTarget,
     IrMemberWithContainerSource,
     IrMetadataSourceOwner {
 
@@ -38,7 +38,6 @@ abstract class IrFunction :
     abstract override val symbol: IrFunctionSymbol
 
     abstract val isInline: Boolean // NB: there's an inline constructor for Array and each primitive array class
-    abstract val isExternal: Boolean
     abstract val isExpect: Boolean
 
     abstract var returnType: IrType

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

@@ -21,10 +21,9 @@ import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.symbols.IrPropertySymbol
 import org.jetbrains.kotlin.ir.visitors.IrElementTransformer
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
-import org.jetbrains.kotlin.serialization.deserialization.descriptors.DeserializedContainerSource
 
 abstract class IrProperty :
-    IrDeclarationBase(), IrOverridableMember, IrMetadataSourceOwner, IrAttributeContainer, IrMemberWithContainerSource {
+    IrDeclarationBase(), IrPossiblyExternalDeclaration, IrOverridableMember, IrMetadataSourceOwner, IrAttributeContainer, IrMemberWithContainerSource {
     @ObsoleteDescriptorBasedAPI
     abstract override val descriptor: PropertyDescriptor
     abstract override val symbol: IrPropertySymbol
@@ -33,7 +32,6 @@ abstract class IrProperty :
     abstract val isConst: Boolean
     abstract val isLateinit: Boolean
     abstract val isDelegated: Boolean
-    abstract val isExternal: Boolean
     abstract val isExpect: Boolean
     abstract val isFakeOverride: Boolean
 

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/lazy/IrLazyClass.kt

@@ -32,7 +32,7 @@ class IrLazyClass(
     override val isCompanion: Boolean,
     override val isInner: Boolean,
     override val isData: Boolean,
-    override val isExternal: Boolean,
+    override var isExternal: Boolean,
     override val isInline: Boolean,
     override val isExpect: Boolean,
     override val isFun: Boolean,

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/lazy/IrLazyConstructor.kt

@@ -30,7 +30,7 @@ class IrLazyConstructor(
     override val name: Name,
     override var visibility: DescriptorVisibility,
     override val isInline: Boolean,
-    override val isExternal: Boolean,
+    override var isExternal: Boolean,
     override val isPrimary: Boolean,
     override val isExpect: Boolean,
     override val stubGenerator: DeclarationStubGenerator,

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/lazy/IrLazyField.kt

@@ -32,7 +32,7 @@ class IrLazyField(
     override val name: Name,
     override var visibility: DescriptorVisibility,
     override val isFinal: Boolean,
-    override val isExternal: Boolean,
+    override var isExternal: Boolean,
     override val isStatic: Boolean,
     override val stubGenerator: DeclarationStubGenerator,
     override val typeTranslator: TypeTranslator,

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/lazy/IrLazyFunction.kt

@@ -34,7 +34,7 @@ class IrLazyFunction(
     override var visibility: DescriptorVisibility,
     override val modality: Modality,
     override val isInline: Boolean,
-    override val isExternal: Boolean,
+    override var isExternal: Boolean,
     override val isTailrec: Boolean,
     override val isSuspend: Boolean,
     override val isExpect: Boolean,

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/lazy/IrLazyProperty.kt

@@ -34,7 +34,7 @@ class IrLazyProperty(
     override val isConst: Boolean,
     override val isLateinit: Boolean,
     override val isDelegated: Boolean,
-    override val isExternal: Boolean,
+    override var isExternal: Boolean,
     override val isExpect: Boolean,
     override val isFakeOverride: Boolean,
     override val stubGenerator: DeclarationStubGenerator,

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

@@ -313,23 +313,12 @@ fun IrCall.isSuperToAny() = superQualifierSymbol?.let { this.symbol.owner.isFake
 fun IrDeclaration.hasInterfaceParent() =
     parent.safeAs<IrClass>()?.isInterface == true
 
-fun IrDeclaration.isEffectivelyExternal(): Boolean {
 
-    fun IrFunction.effectiveParentDeclaration(): IrDeclaration? =
+fun IrPossiblyExternalDeclaration.isEffectivelyExternal(): Boolean =
-        when (this) {
+    this.isExternal
-            is IrSimpleFunction -> correspondingPropertySymbol?.owner ?: parent as? IrDeclaration
-            else -> parent as? IrDeclaration
-        }
 
-    val parent = parent
+fun IrDeclaration.isEffectivelyExternal(): Boolean =
-    return when (this) {
+    this is IrPossiblyExternalDeclaration && this.isExternal
-        is IrFunction -> isExternal || (effectiveParentDeclaration()?.isEffectivelyExternal() ?: false)
-        is IrField -> isExternal || parent is IrDeclaration && parent.isEffectivelyExternal()
-        is IrProperty -> isExternal || parent is IrDeclaration && parent.isEffectivelyExternal()
-        is IrClass -> isExternal || parent is IrDeclaration && parent.isEffectivelyExternal()
-        else -> false
-    }
-}
 
 fun IrFunction.isExternalOrInheritedFromExternal(): Boolean {
     fun isExternalOrInheritedFromExternalImpl(f: IrSimpleFunction): Boolean =