[IR] Make IrFunctionSymbol a sealed interface

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/generators/AdapterGenerator.kt

@@ -308,8 +308,6 @@ internal class AdapterGenerator(
                     origin = null,
                     superQualifierSymbol = null
                 )
-            else ->
-                error("unknown callee kind: ${adapteeFunction.render()}")
         }
 
         var adapterParameterIndex = 0

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

@@ -13,6 +13,7 @@ import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.*
 import org.jetbrains.kotlin.ir.symbols.IrConstructorSymbol
+import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
 import org.jetbrains.kotlin.ir.symbols.IrValueParameterSymbol
 import org.jetbrains.kotlin.ir.symbols.IrValueSymbol
 import org.jetbrains.kotlin.ir.types.classOrNull
@@ -261,10 +262,9 @@ class InnerClassConstructorCallsLowering(val context: BackendContext, val innerC
 
                 val newCallee = innerClassesSupport.getInnerClassConstructorWithOuterThisParameter(callee.owner)
                 val newReflectionTarget = expression.reflectionTarget?.let { reflectionTarget ->
-                    if (reflectionTarget is IrConstructorSymbol) {
+                    when (reflectionTarget) {
-                        innerClassesSupport.getInnerClassConstructorWithOuterThisParameter(reflectionTarget.owner)
+                        is IrConstructorSymbol -> innerClassesSupport.getInnerClassConstructorWithOuterThisParameter(reflectionTarget.owner)
-                    } else {
+                        is IrSimpleFunctionSymbol -> null
-                        null
                     }
                 }
 

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

@@ -115,7 +115,6 @@ class CachedSyntheticDeclarations(private val context: JvmBackendContext) {
                     symbol.owner.makeConstructorAccessor().symbol
                 is IrSimpleFunctionSymbol ->
                     symbol.owner.makeSimpleFunctionAccessor(superQualifierSymbol, dispatchReceiverType, parent, scopes).symbol
-                else -> error("Unknown subclass of IrFunctionSymbol")
             }
         }
     }

compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/ReflectionReferencesGenerator.kt

@@ -313,7 +313,6 @@ internal class ReflectionReferencesGenerator(statementGenerator: StatementGenera
                 IrConstructorCallImpl.fromSymbolDescriptor(startOffset, endOffset, irType, adapteeSymbol)
             is IrSimpleFunctionSymbol ->
                 IrCallImpl.fromSymbolDescriptor(startOffset, endOffset, irType, adapteeSymbol)
-            else -> error("Unknown symbol kind $adapteeSymbol")
         }
 
         val hasBoundDispatchReceiver = resolvedCall.dispatchReceiver != null && resolvedCall.dispatchReceiver !is TransientReceiver

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/ExpressionHelpers.kt

@@ -272,7 +272,6 @@ fun IrBuilderWithScope.irCall(callee: IrFunctionSymbol, type: IrType): IrFunctio
     when (callee) {
         is IrConstructorSymbol -> irCall(callee, type)
         is IrSimpleFunctionSymbol -> irCall(callee, type)
-        else -> throw AssertionError("Unexpected callee: $callee")
     }
 
 fun IrBuilderWithScope.irCall(callee: IrSimpleFunctionSymbol): IrCall =

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

@@ -98,7 +98,7 @@ interface IrReturnTargetSymbol : IrSymbol {
     override val owner: IrReturnTarget
 }
 
-interface IrFunctionSymbol : IrReturnTargetSymbol {
+sealed interface IrFunctionSymbol : IrReturnTargetSymbol {
     override val owner: IrFunction
 }
 

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

@@ -219,7 +219,6 @@ open class DeepCopySymbolRemapper(
         when (symbol) {
             is IrSimpleFunctionSymbol -> functions.getReferenced(symbol)
             is IrConstructorSymbol -> constructors.getReferenced(symbol)
-            else -> throw IllegalArgumentException("Unexpected symbol $symbol")
         }
 
     override fun getReferencedReturnableBlock(symbol: IrReturnableBlockSymbol): IrReturnableBlockSymbol =

compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/linkage/partial/PartiallyLinkedIrTreePatcher.kt

@@ -708,7 +708,6 @@ internal class PartiallyLinkedIrTreePatcher(
                     val expectedDispatchReceiverClassifier: IrClassSymbol = when (symbol) {
                         is IrSimpleFunctionSymbol -> function.parent as? IrClass
                         is IrConstructorSymbol -> (function.parent as? IrClass)?.takeIf { it.isInner }?.parent as? IrClass
-                        else -> null
                     }?.symbol ?: return@run false
 
                     val referenceType: IrSimpleType = type as? IrSimpleType ?: return@run false

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

@@ -130,7 +130,6 @@ internal class ExpectToActualDefaultValueCopier(private val irModule: IrModuleFr
             override fun getReferencedFunction(symbol: IrFunctionSymbol): IrFunctionSymbol = when (symbol) {
                 is IrSimpleFunctionSymbol -> getReferencedSimpleFunction(symbol)
                 is IrConstructorSymbol -> getReferencedConstructor(symbol)
-                else -> error("Unexpected symbol $symbol ${symbol.descriptor}")
             }
 
             override fun getReferencedSimpleFunction(symbol: IrSimpleFunctionSymbol) = when {