[IR] Make IrClassifierSymbol a sealed interface

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrDeclarationStorage.kt

@@ -158,7 +158,7 @@ class Fir2IrDeclarationStorage(
                                 val irClass = irClassifierSymbol.owner
                                 firType is ConeClassLikeType && irClass.name == firType.lookupTag.name
                             }
-                            else -> {
+                            is IrScriptSymbol -> {
                                 false
                             }
                         }

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/IrTypeUtils.kt

@@ -14,6 +14,7 @@ import org.jetbrains.kotlin.ir.symbols.IrTypeParameterSymbol
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.util.fqNameWhenAvailable
 import org.jetbrains.kotlin.ir.util.isEffectivelyExternal
+import org.jetbrains.kotlin.ir.util.unexpectedSymbolKind
 import org.jetbrains.kotlin.js.backend.ast.JsNameRef
 import org.jetbrains.kotlin.types.Variance
 import org.jetbrains.kotlin.utils.addToStdlib.ifNotEmpty
@@ -44,18 +45,13 @@ private fun IrTypeArgument.asString(): String = when (this) {
 private fun IrClassifierSymbol.asString() = when (this) {
     is IrTypeParameterSymbol -> this.owner.name.asString()
     is IrClassSymbol -> this.owner.fqNameWhenAvailable!!.asString()
-    else -> error("Unexpected kind of IrClassifierSymbol: " + javaClass.typeName)
+    is IrScriptSymbol -> unexpectedSymbolKind<IrClassifierSymbol>()
 }
 
-tailrec fun erase(type: IrType): IrClass? {
+tailrec fun erase(type: IrType): IrClass? = when (val classifier = type.classifierOrFail) {
-    val classifier = type.classifierOrFail
+    is IrClassSymbol -> classifier.owner
-
+    is IrTypeParameterSymbol -> erase(classifier.owner.superTypes.first())
-    return when (classifier) {
+    is IrScriptSymbol -> null
-        is IrClassSymbol -> classifier.owner
-        is IrTypeParameterSymbol -> erase(classifier.owner.superTypes.first())
-        is IrScriptSymbol -> null
-        else -> error(classifier)
-    }
 }
 
 fun IrType.getClassRef(context: JsGenerationContext): JsNameRef =

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/ir/JvmIrTypeUtils.kt

@@ -13,6 +13,7 @@ import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.expressions.impl.IrCallImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrConstImpl
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
+import org.jetbrains.kotlin.ir.symbols.IrClassifierSymbol
 import org.jetbrains.kotlin.ir.symbols.IrScriptSymbol
 import org.jetbrains.kotlin.ir.symbols.IrTypeParameterSymbol
 import org.jetbrains.kotlin.ir.types.*
@@ -21,6 +22,7 @@ import org.jetbrains.kotlin.ir.types.impl.IrStarProjectionImpl
 import org.jetbrains.kotlin.ir.types.impl.makeTypeProjection
 import org.jetbrains.kotlin.ir.util.isLocal
 import org.jetbrains.kotlin.ir.util.render
+import org.jetbrains.kotlin.ir.util.unexpectedSymbolKind
 
 /**
  * Perform as much type erasure as is significant for JVM signature generation.
@@ -87,7 +89,7 @@ val IrType.erasedUpperBound: IrClass
             is IrClassSymbol -> classifier.owner
             is IrTypeParameterSymbol -> classifier.owner.erasedUpperBound
             is IrScriptSymbol -> classifier.owner.targetClass!!.owner
-            else -> if (this is IrErrorType) symbol.owner else error(render())
+            null -> if (this is IrErrorType) symbol.owner else error(render())
         }
 
 /**
@@ -139,7 +141,7 @@ fun IrType.eraseToScope(visibleTypeParameters: Set<IrTypeParameter>): IrType {
                 this
             else
                 upperBound.mergeNullability(this)
-        else -> error("unknown IrType classifier kind: ${classifier.owner.render()}")
+        is IrScriptSymbol -> classifier.unexpectedSymbolKind<IrClassifierSymbol>()
     }
 }
 

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

@@ -1211,7 +1211,6 @@ private fun makeKotlinType(
                 KotlinTypeFactory.EMPTY_REFINED_TYPE_FACTORY
             ).makeNullableAsSpecified(hasQuestionMark)
         }
-        else -> error("unknown classifier kind $classifier")
     }
 
 /* When IR-based descriptors are used from Psi2Ir, symbols may be unbound, thus we may need to resort to real descriptors. */

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/symbols/IrSymbol.kt

@@ -69,7 +69,7 @@ interface IrEnumEntrySymbol : IrBindableSymbol<ClassDescriptor, IrEnumEntry>
 
 interface IrFieldSymbol : IrBindableSymbol<PropertyDescriptor, IrField>
 
-interface IrClassifierSymbol : IrSymbol, TypeConstructorMarker {
+sealed interface IrClassifierSymbol : IrSymbol, TypeConstructorMarker {
     @ObsoleteDescriptorBasedAPI
     override val descriptor: ClassifierDescriptor
 }

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/types/IrTypeUtils.kt

@@ -14,7 +14,7 @@ import org.jetbrains.kotlin.types.AbstractTypeChecker
 fun IrClassifierSymbol.superTypes(): List<IrType> = when (this) {
     is IrClassSymbol -> owner.superTypes
     is IrTypeParameterSymbol -> owner.superTypes
-    else -> emptyList()
+    is IrScriptSymbol -> emptyList()
 }
 
 fun IrClassifierSymbol.isSubtypeOfClass(superClass: IrClassSymbol): Boolean =
@@ -44,7 +44,6 @@ fun IrType.isNullable(): Boolean =
                 SimpleTypeNullability.DEFINITELY_NOT_NULL -> false
             }
             is IrScriptSymbol -> nullability == SimpleTypeNullability.MARKED_NULLABLE
-            else -> error("Unsupported classifier: $classifier")
         }
         is IrDynamicType -> true
         is IrErrorType -> this.isMarkedNullable

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/types/irTypes.kt

@@ -163,7 +163,7 @@ val IrClassifierSymbol.defaultType: IrType
     get() = when (this) {
         is IrClassSymbol -> owner.defaultType
         is IrTypeParameterSymbol -> owner.defaultType
-        else -> error("Unexpected classifier symbol type $this")
+        is IrScriptSymbol -> unexpectedSymbolKind<IrClassifierSymbol>()
     }
 
 val IrTypeParameter.defaultType: IrType

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

@@ -231,7 +231,6 @@ open class DeepCopySymbolRemapper(
             is IrClassSymbol -> classes.getReferenced(symbol)
             is IrScriptSymbol -> scripts.getReferenced(symbol)
             is IrTypeParameterSymbol -> typeParameters.getReferenced(symbol)
-            else -> throw IllegalArgumentException("Unexpected symbol $symbol")
         }
 
     override fun getReferencedTypeAlias(symbol: IrTypeAliasSymbol): IrTypeAliasSymbol = typeAliases.getReferenced(symbol)

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

@@ -1422,3 +1422,7 @@ fun IrAttributeContainer.extractRelatedDeclaration(): IrDeclaration? {
         else -> null
     }
 }
+
+inline fun <reified Symbol : IrSymbol> IrSymbol.unexpectedSymbolKind(): Nothing {
+    throw IllegalArgumentException("Unexpected kind of ${Symbol::class.java.typeName}: $this")
+}

compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/mangle/ir/IrMangleComputer.kt

@@ -10,6 +10,7 @@ import org.jetbrains.kotlin.ir.IrBuiltIns
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
+import org.jetbrains.kotlin.ir.symbols.IrScriptSymbol
 import org.jetbrains.kotlin.ir.symbols.IrTypeParameterSymbol
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.util.*
@@ -133,6 +134,7 @@ open class IrMangleComputer(
                 when (val classifier = type.classifier) {
                     is IrClassSymbol -> with(copy(MangleMode.FQNAME)) { classifier.owner.visit() }
                     is IrTypeParameterSymbol -> tBuilder.mangleTypeParameterReference(classifier)
+                    is IrScriptSymbol -> {}
                 }
 
                 mangleTypeArguments(tBuilder, type, null)

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/InlineClasses.kt

@@ -16,6 +16,8 @@ import org.jetbrains.kotlin.ir.declarations.IrProperty
 import org.jetbrains.kotlin.ir.declarations.inlineClassRepresentation
 import org.jetbrains.kotlin.ir.declarations.isSingleFieldValueClass
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
+import org.jetbrains.kotlin.ir.symbols.IrClassifierSymbol
+import org.jetbrains.kotlin.ir.symbols.IrScriptSymbol
 import org.jetbrains.kotlin.ir.symbols.IrTypeParameterSymbol
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.classifierOrFail
@@ -284,13 +286,10 @@ internal object IrTypeInlineClassesSupport : InlineClassesSupport<IrClass, IrTyp
         }
     }
 
-    override fun computeFullErasure(type: IrType): Sequence<IrClass> {
+    override fun computeFullErasure(type: IrType): Sequence<IrClass> = when (val classifier = type.classifierOrFail) {
-        val classifier = type.classifierOrFail
+        is IrClassSymbol -> sequenceOf(classifier.owner)
-        return when (classifier) {
+        is IrTypeParameterSymbol -> classifier.owner.superTypes.asSequence().flatMap { computeFullErasure(it) }
-            is IrClassSymbol -> sequenceOf(classifier.owner)
+        is IrScriptSymbol -> classifier.unexpectedSymbolKind<IrClassifierSymbol>()
-            is IrTypeParameterSymbol -> classifier.owner.superTypes.asSequence().flatMap { computeFullErasure(it) }
-            else -> error(classifier)
-        }
     }
 
     override fun hasInlineModifier(clazz: IrClass): Boolean = clazz.isSingleFieldValueClass

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/ExpectDeclarationsRemoving.kt

@@ -119,7 +119,7 @@ internal class ExpectToActualDefaultValueCopier(private val irModule: IrModuleFr
             override fun getReferencedClassifier(symbol: IrClassifierSymbol): IrClassifierSymbol = when (symbol) {
                 is IrClassSymbol -> getReferencedClass(symbol)
                 is IrTypeParameterSymbol -> remapExpectTypeParameter(symbol).symbol
-                else -> error("Unexpected symbol $symbol ${symbol.descriptor}")
+                is IrScriptSymbol -> symbol.unexpectedSymbolKind<IrClassifierSymbol>()
             }
 
             override fun getReferencedConstructor(symbol: IrConstructorSymbol) =

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/ReflectionSupport.kt

@@ -15,6 +15,8 @@ import org.jetbrains.kotlin.ir.builders.*
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
+import org.jetbrains.kotlin.ir.symbols.IrClassifierSymbol
+import org.jetbrains.kotlin.ir.symbols.IrScriptSymbol
 import org.jetbrains.kotlin.ir.symbols.IrTypeParameterSymbol
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.util.*
@@ -65,7 +67,7 @@ internal class KTypeGenerator(
                     // Leave upper bounds of non-reified type parameters as is, even if they are reified themselves.
                     irKTypeParameter(classifier.owner, leaveReifiedForLater = false, seenTypeParameters = seenTypeParameters)
                 }
-                else -> TODO("Unexpected classifier: $classifier")
+                is IrScriptSymbol -> classifier.unexpectedSymbolKind<IrClassifierSymbol>()
             }
 
             return irKTypeImpl(

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/TypeOperatorLowering.kt

@@ -14,6 +14,8 @@ import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.expressions.IrTypeOperator
 import org.jetbrains.kotlin.ir.expressions.IrTypeOperatorCall
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
+import org.jetbrains.kotlin.ir.symbols.IrClassifierSymbol
+import org.jetbrains.kotlin.ir.symbols.IrScriptSymbol
 import org.jetbrains.kotlin.ir.symbols.IrTypeParameterSymbol
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.util.*
@@ -36,7 +38,7 @@ internal fun IrType.erasure(): IrType {
             // In the second case, there is only a single supertype.
             classifier.owner.superTypes.first().erasure()
         }
-        else -> TODO(classifier.toString())
+        is IrScriptSymbol -> classifier.unexpectedSymbolKind<IrClassifierSymbol>()
     }
 
     return upperBound.mergeNullability(this)

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/ir/util/IrUtils2.kt

@@ -27,10 +27,7 @@ import org.jetbrains.kotlin.ir.declarations.impl.IrValueParameterImpl
 import org.jetbrains.kotlin.ir.declarations.impl.IrVariableImpl
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.*
-import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
+import org.jetbrains.kotlin.ir.symbols.*
-import org.jetbrains.kotlin.ir.symbols.IrFunctionSymbol
-import org.jetbrains.kotlin.ir.symbols.IrSymbol
-import org.jetbrains.kotlin.ir.symbols.IrTypeParameterSymbol
 import org.jetbrains.kotlin.ir.symbols.impl.IrFieldSymbolImpl
 import org.jetbrains.kotlin.ir.symbols.impl.IrValueParameterSymbolImpl
 import org.jetbrains.kotlin.ir.symbols.impl.IrVariableSymbolImpl
@@ -172,8 +169,7 @@ fun IrFunctionAccessExpression.addArguments(args: Map<IrValueParameter, IrExpres
 fun IrType.substitute(map: Map<IrTypeParameterSymbol, IrType>): IrType {
     if (this !is IrSimpleType) return this
 
-    val classifier = this.classifier
+    return when (val classifier = this.classifier) {
-    return when (classifier) {
         is IrTypeParameterSymbol ->
             map[classifier]?.mergeNullability(this) ?: this
         is IrClassSymbol -> if (this.arguments.isEmpty()) {
@@ -187,7 +183,7 @@ fun IrType.substitute(map: Map<IrTypeParameterSymbol, IrType>): IrType {
             }
             IrSimpleTypeImpl(classifier, nullability, newArguments, annotations)
         }
-        else -> error(classifier)
+        is IrScriptSymbol -> classifier.unexpectedSymbolKind<IrClassifierSymbol>()
     }
 
 }

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

@@ -248,11 +248,11 @@ fun findSerializerConstructorForTypeArgumentsSerializers(serializer: IrClass): I
     }?.symbol
 }
 
-fun IrType.classOrUpperBound(): IrClassSymbol? = when(val cls = classifierOrNull) {
+fun IrType.classOrUpperBound(): IrClassSymbol? = when (val cls = classifierOrNull) {
     is IrClassSymbol -> cls
     is IrScriptSymbol -> cls.owner.targetClass
     is IrTypeParameterSymbol -> cls.owner.representativeUpperBound.classOrUpperBound()
-    else -> null
+    null -> null
 }
 
 /**