Removed useless as casts from compiler code

It allows compiling code with K2 and enabled `-Werror`

analysis/analysis-api-fe10/src/org/jetbrains/kotlin/analysis/api/descriptors/components/KtFe10ExpressionTypeProvider.kt

@@ -300,10 +300,9 @@ class KtFe10ExpressionTypeProvider(
     }
 
     override fun isDefinitelyNotNull(expression: KtExpression): Boolean {
-        val ktExpression = expression as? KtExpression ?: return false
+        val bindingContext = analysisContext.analyze(expression)
-        val bindingContext = analysisContext.analyze(ktExpression)
 
-        val smartCasts = bindingContext[BindingContext.SMARTCAST, ktExpression]
+        val smartCasts = bindingContext[BindingContext.SMARTCAST, expression]
 
         if (smartCasts is MultipleSmartCasts) {
             if (smartCasts.map.values.all { !it.isMarkedNullable }) {

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/symbols/pointers/KtFirMemberSymbolPointer.kt

@@ -13,7 +13,6 @@ import org.jetbrains.kotlin.analysis.api.symbols.markers.KtSymbolWithMembers
 import org.jetbrains.kotlin.analysis.api.symbols.pointers.KtSymbolPointer
 import org.jetbrains.kotlin.analysis.utils.errors.requireIsInstance
 import org.jetbrains.kotlin.fir.FirSession
-import org.jetbrains.kotlin.fir.declarations.FirClass
 import org.jetbrains.kotlin.fir.declarations.FirResolvePhase
 import org.jetbrains.kotlin.fir.scopes.FirScope
 import org.jetbrains.kotlin.fir.scopes.unsubstitutedScope
@@ -42,7 +41,7 @@ internal abstract class KtFirMemberSymbolPointer<S : KtSymbol>(
         val firSession = useSiteSession
         val scopeSession = getScopeSessionFor(firSession)
         return if (isStatic) {
-            val firClass = owner.fir as? FirClass ?: return null
+            val firClass = owner.fir
             firClass.scopeProvider.getStaticMemberScopeForCallables(firClass, firSession, scopeSession)
         } else {
             owner.unsubstitutedScope(

analysis/analysis-api-impl-base/tests/org/jetbrains/kotlin/analysis/api/impl/base/test/cases/components/symbolDeclarationRenderer/AbstractRendererTest.kt

@@ -36,8 +36,7 @@ abstract class AbstractRendererTest : AbstractAnalysisApiSingleFileTest() {
             buildString {
                 ktFile.declarations.forEach { declaration ->
                     analyseForTest(declaration) {
-                        val symbol = declaration.getSymbol() as? KtDeclarationSymbol ?: return@analyseForTest
+                        append(declaration.getSymbol().render(renderer))
-                        append(symbol.render(renderer))
                         appendLine()
                         appendLine()
                     }

analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/stubBased/deserialization/StubBasedFirTypeDeserializer.kt

@@ -108,7 +108,7 @@ internal class StubBasedFirTypeDeserializer(
         val annotations = annotationDeserializer.loadAnnotations(typeReference).toMutableList()
         val parent = (typeReference.stub ?: loadStubByElement(typeReference))?.parentStub
         if (parent is KotlinParameterStubImpl) {
-            (parent as? KotlinParameterStubImpl)?.functionTypeParameterName?.let { paramName ->
+            parent.functionTypeParameterName?.let { paramName ->
                 annotations += buildAnnotation {
                     annotationTypeRef = buildResolvedTypeRef {
                         type = StandardNames.FqNames.parameterNameClassId.toLookupTag()

compiler/backend/src/org/jetbrains/kotlin/codegen/inline/PsiInlineCodegen.kt

@@ -194,8 +194,7 @@ class PsiInlineCodegen(
     override fun reorderArgumentsIfNeeded(actualArgsWithDeclIndex: List<ArgumentAndDeclIndex>, valueParameterTypes: List<Type>) = Unit
 
     override fun isInlinedToInlineFunInKotlinRuntime(): Boolean {
-        val codegen = this.codegen as? ExpressionCodegen ?: return false
+        val caller = this.codegen.context.functionDescriptor
-        val caller = codegen.context.functionDescriptor
         if (!caller.isInline) return false
         val callerPackage = DescriptorUtils.getParentOfType(caller, PackageFragmentDescriptor::class.java) ?: return false
         return callerPackage.fqName.asString().startsWith("kotlin.")

compiler/backend/src/org/jetbrains/kotlin/codegen/range/PrimitiveNumberRangeIntrinsicRangeValue.kt

@@ -65,8 +65,7 @@ abstract class PrimitiveNumberRangeIntrinsicRangeValue(
 
         return when (comparisonGenerator.comparedType) {
             Type.DOUBLE_TYPE, Type.FLOAT_TYPE -> {
-                val rangeLiteral = getBoundedValue(codegen) as? BoundedValue
+                val rangeLiteral = getBoundedValue(codegen)
-                    ?: throw AssertionError("Floating point intrinsic range value should be a range literal")
                 InFloatingPointRangeLiteralExpressionGenerator(operatorReference, rangeLiteral, comparisonGenerator, codegen.frameMap)
             }
             else ->

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/pipeline/compilerPipeline.kt

@@ -274,9 +274,7 @@ fun compileModuleToAnalyzedFir(
         incrementalExcludesScope
     )?.also { librariesScope -= it }
 
-    val extensionRegistrars = (projectEnvironment as? VfsBasedProjectEnvironment)
+    val extensionRegistrars = FirExtensionRegistrar.getInstances(projectEnvironment.project)
-        ?.let { FirExtensionRegistrar.getInstances(it.project) }
-        ?: emptyList()
 
     val allSources = mutableListOf<KtSourceFile>().apply {
         addAll(input.groupedSources.commonSources)

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/FirUpperBoundViolatedHelpers.kt

@@ -190,8 +190,7 @@ fun checkUpperBoundViolated(
         if (argumentType != null && argumentSource != null) {
             if (!isIgnoreTypeParameters || (argumentType.typeArguments.isEmpty() && argumentType !is ConeTypeParameterType)) {
                 val intersection =
-                    typeSystemContext.intersectTypes(typeParameters[index].resolvedBounds.map { it.coneType }) as? ConeKotlinType
+                    typeSystemContext.intersectTypes(typeParameters[index].resolvedBounds.map { it.coneType })
-                if (intersection != null) {
                 val upperBound = substitutor.substituteOrSelf(intersection)
                 if (!AbstractTypeChecker.isSubtypeOf(
                         typeSystemContext,
@@ -207,7 +206,6 @@ fun checkUpperBoundViolated(
                     reporter.reportOn(argumentSource, factory, upperBound, argumentType.type, context)
                 }
             }
-            }
 
             if (argumentType is ConeClassLikeType) {
                 checkUpperBoundViolated(argumentTypeRef, argumentType, context, reporter, isIgnoreTypeParameters)

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirTopLevelPropertiesChecker.kt

@@ -27,7 +27,6 @@ import org.jetbrains.kotlin.fir.declarations.utils.*
 import org.jetbrains.kotlin.fir.resolve.dfa.cfg.NormalPath
 import org.jetbrains.kotlin.fir.resolve.dfa.controlFlowGraph
 import org.jetbrains.kotlin.fir.resolve.diagnostics.ConeLocalVariableNoTypeOrInitializer
-import org.jetbrains.kotlin.fir.symbols.impl.FirPropertySymbol
 import org.jetbrains.kotlin.fir.types.FirErrorTypeRef
 import org.jetbrains.kotlin.lexer.KtTokens
 
@@ -58,7 +57,7 @@ object FirTopLevelPropertiesChecker : FirFileChecker() {
         }
 
         val propertySymbols = topLevelProperties.mapNotNullTo(mutableSetOf()) { declaration ->
-            (declaration.symbol as? FirPropertySymbol)?.takeIf { it.requiresInitialization(isForInitialization = true) }
+            declaration.symbol.takeIf { it.requiresInitialization(isForInitialization = true) }
         }
         if (propertySymbols.isEmpty()) return null
 

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirValueClassDeclarationChecker.kt

@@ -284,7 +284,7 @@ object FirValueClassDeclarationChecker : FirRegularClassChecker() {
 
         return lookupSuperTypes(this, lookupInterfaces = true, deep = true, session, substituteTypes = false).any { superType ->
             // Note: We check just classId here, so type substitution isn't needed   ^ (we aren't interested in type arguments)
-            (superType as? ConeClassLikeType)?.fullyExpandedType(session)?.lookupTag?.classId?.isCloneableId() == true
+            superType.fullyExpandedType(session).lookupTag.classId.isCloneableId()
         }
     }
 

compiler/fir/fir2ir/jvm-backend/src/org/jetbrains/kotlin/fir/backend/jvm/FirJvmTypeMapper.kt

@@ -136,8 +136,8 @@ class FirJvmTypeMapper(val session: FirSession) : FirSessionComponent {
             return when (val symbol = lookupTag.toSymbol(session)) {
                 is FirRegularClassSymbol -> buildPossiblyInnerType(symbol, 0)
                 is FirTypeAliasSymbol -> {
-                    val expandedType = fullyExpandedType(session) as? ConeClassLikeType
+                    val expandedType = fullyExpandedType(session)
-                    val classSymbol = expandedType?.lookupTag?.toSymbol(session) as? FirRegularClassSymbol
+                    val classSymbol = expandedType.lookupTag.toSymbol(session) as? FirRegularClassSymbol
                     classSymbol?.let { expandedType.buildPossiblyInnerType(it, 0) }
                 }
                 else -> null

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

@@ -369,13 +369,13 @@ class DelegatedMemberGenerator(private val components: Fir2IrComponents) : Fir2I
             subClassLookupTag: ConeClassLikeLookupTag,
             firField: FirField,
         ): D? {
-            val callable = this.fir as? D ?: return null
+            val callable = this.fir
 
             val delegatedWrapperData = callable.delegatedWrapperData ?: return null
             if (delegatedWrapperData.containingClass != subClassLookupTag) return null
             if (delegatedWrapperData.delegateField != firField) return null
 
-            val wrapped = delegatedWrapperData.wrapped as? D ?: return null
+            val wrapped = delegatedWrapperData.wrapped
 
             @Suppress("UNCHECKED_CAST")
             val wrappedSymbol = wrapped.symbol as? S ?: return null

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

@@ -442,8 +442,7 @@ class FakeOverrideGenerator(
             overridden.containingClassLookupTag()?.toSymbol(session)?.fir as? FirClass ?: return emptyList()
 
         val overriddenContainingIrClass =
-            declarationStorage.classifierStorage.getOrCreateIrClass(overriddenContainingClass.symbol).symbol.owner as? IrClass
+            declarationStorage.classifierStorage.getOrCreateIrClass(overriddenContainingClass.symbol).symbol.owner
-                ?: return emptyList()
 
         return superClasses.mapNotNull { superClass ->
             if (superClass == overriddenContainingIrClass ||

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/scopes/JavaClassStaticUseSiteScope.kt

@@ -12,7 +12,6 @@ import org.jetbrains.kotlin.fir.scopes.FirContainingNamesAwareScope
 import org.jetbrains.kotlin.fir.symbols.impl.FirNamedFunctionSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirVariableSymbol
 import org.jetbrains.kotlin.name.Name
-import org.jetbrains.kotlin.utils.addIfNotNull
 
 class JavaClassStaticUseSiteScope internal constructor(
     session: FirSession,
@@ -34,7 +33,7 @@ class JavaClassStaticUseSiteScope internal constructor(
     private fun computeFunctions(name: Name): MutableList<FirNamedFunctionSymbol> {
         val superClassSymbols = mutableListOf<FirNamedFunctionSymbol>()
         superClassScope.processFunctionsByName(name) {
-            superClassSymbols.addIfNotNull(it as? FirNamedFunctionSymbol)
+            superClassSymbols.add(it)
         }
 
         val result = mutableListOf<FirNamedFunctionSymbol>()

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/Arguments.kt

@@ -22,7 +22,6 @@ import org.jetbrains.kotlin.fir.resolve.inference.model.ConeReceiverConstraintPo
 import org.jetbrains.kotlin.fir.resolve.inference.preprocessCallableReference
 import org.jetbrains.kotlin.fir.resolve.inference.preprocessLambdaArgument
 import org.jetbrains.kotlin.fir.resolve.transformers.ReturnTypeCalculator
-import org.jetbrains.kotlin.fir.resolve.transformers.body.resolve.resultType
 import org.jetbrains.kotlin.fir.resolve.transformers.ensureResolvedTypeDeclaration
 import org.jetbrains.kotlin.fir.returnExpressions
 import org.jetbrains.kotlin.fir.symbols.ConeClassLikeLookupTag
@@ -362,9 +361,7 @@ private fun checkApplicabilityForArgumentType(
                     return ConeTypeIntersector.intersectTypes(context.session.typeContext, constraintTypes)
                 }
 
-                val originalTypeParameter =
+                val originalTypeParameter = lookupTag.originalTypeParameter as? ConeTypeParameterLookupTag
-                    (lookupTag as? ConeTypeVariableTypeConstructor)?.originalTypeParameter as? ConeTypeParameterLookupTag
-
                 if (originalTypeParameter != null)
                     return ConeTypeParameterTypeImpl(originalTypeParameter, type.isNullable, type.attributes)
             } else if (type is ConeIntegerLiteralType) {

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/SuperCalls.kt

@@ -10,7 +10,6 @@ import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.descriptors.isClass
 import org.jetbrains.kotlin.fir.declarations.FirCallableDeclaration
 import org.jetbrains.kotlin.fir.declarations.FirResolvePhase
-import org.jetbrains.kotlin.fir.declarations.FirVariable
 import org.jetbrains.kotlin.fir.declarations.utils.modality
 import org.jetbrains.kotlin.fir.dispatchReceiverClassLookupTagOrNull
 import org.jetbrains.kotlin.fir.expressions.FirFunctionCall
@@ -27,7 +26,6 @@ import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.name.StandardClassIds
 import org.jetbrains.kotlin.types.AbstractTypeChecker
 import org.jetbrains.kotlin.utils.SmartList
-import org.jetbrains.kotlin.utils.addIfNotNull
 
 fun BodyResolveComponents.findTypesForSuperCandidates(
     superTypeRefs: List<FirTypeRef>,
@@ -144,7 +142,7 @@ private fun BodyResolveComponents.getPropertyMembers(type: ConeKotlinType, name:
             scopeSession = scopeSession,
             callableCopyTypeCalculator = CallableCopyTypeCalculator.DoNothing,
             requiredMembersPhase = FirResolvePhase.STATUS,
-        )?.processPropertiesByName(name) { addIfNotNull(it.fir as? FirVariable) }
+        )?.processPropertiesByName(name) { add(it.fir) }
     }
 
 

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/inference/ConstraintSystemCompleter.kt

@@ -421,7 +421,7 @@ class ConstraintSystemCompleter(components: BodyResolveComponents, private val c
                     processBlocks = true
                 ) { candidate ->
                     candidate.postponedAtoms.forEach { atom ->
-                        notAnalyzedArguments.addIfNotNull((atom as? PostponedResolvedAtom)?.takeUnless { it.analyzed })
+                        notAnalyzedArguments.addIfNotNull(atom.takeUnless { it.analyzed })
                     }
                 }
             }

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/body/resolve/FirExpressionsResolveTransformer.kt

@@ -1027,7 +1027,7 @@ open class FirExpressionsResolveTransformer(transformer: FirAbstractBodyResolveT
             ),
         )
 
-        (result as? FirVariableAssignment)?.let { dataFlowAnalyzer.exitVariableAssignment(it) }
+        dataFlowAnalyzer.exitVariableAssignment(result)
 
         return result
     }

compiler/fir/semantics/src/org/jetbrains/kotlin/fir/declarations/ImplicitReceiverUtils.kt

@@ -22,10 +22,8 @@ import org.jetbrains.kotlin.fir.types.ConeErrorType
 import org.jetbrains.kotlin.fir.types.ConeKotlinType
 import org.jetbrains.kotlin.fir.types.ConeStubType
 import org.jetbrains.kotlin.fir.types.coneType
-import org.jetbrains.kotlin.fir.utils.exceptions.withConeTypeEntry
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.utils.addIfNotNull
-import org.jetbrains.kotlin.utils.exceptions.errorWithAttachment
 
 fun SessionHolder.collectImplicitReceivers(
     type: ConeKotlinType?,
@@ -87,7 +85,7 @@ fun SessionHolder.collectTowerDataElementsForClass(owner: FirClass, defaultType:
             ?.asTowerDataElementForStaticScope(staticScopeOwnerSymbol = superClass.symbol)
             ?.let(superClassesStaticsAndCompanionReceivers::add)
 
-        (superClass as? FirRegularClass)?.companionObjectSymbol?.let {
+        superClass.companionObjectSymbol?.let {
             val superCompanionReceiver = ImplicitDispatchReceiverValue(
                 it, session, scopeSession
             )

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/checkers/NullableVarargArgumentCallChecker.kt

@@ -15,7 +15,6 @@ import org.jetbrains.kotlin.resolve.calls.model.ResolvedCall
 import org.jetbrains.kotlin.resolve.calls.model.VariableAsFunctionResolvedCall
 import org.jetbrains.kotlin.resolve.calls.tower.NewResolvedCallImpl
 import org.jetbrains.kotlin.resolve.calls.tower.SimplePSIKotlinCallArgument
-import org.jetbrains.kotlin.resolve.scopes.receivers.ReceiverValueWithSmartCastInfo
 import org.jetbrains.kotlin.types.FlexibleType
 import org.jetbrains.kotlin.types.TypeUtils
 
@@ -32,7 +31,7 @@ object NullableVarargArgumentCallChecker : CallChecker {
                 if (!arg.isSpread || arg !is SimplePSIKotlinCallArgument) continue
 
                 val spreadElement = arg.valueArgument.getSpreadElement() ?: continue
-                val receiver = (arg.receiver as? ReceiverValueWithSmartCastInfo) ?: continue
+                val receiver = arg.receiver
 
                 val type = if (receiver.stableType.constructor is TypeVariableTypeConstructor) {
                     context.trace.bindingContext[EXPRESSION_TYPE_INFO, arg.valueArgument.getArgumentExpression()]?.type

compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ValueClassDeclarationChecker.kt

@@ -5,7 +5,6 @@
 
 package org.jetbrains.kotlin.resolve.checkers
 
-import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.builtins.StandardNames
 import org.jetbrains.kotlin.config.LanguageFeature
 import org.jetbrains.kotlin.descriptors.*
@@ -89,7 +88,7 @@ object ValueClassDeclarationChecker : DeclarationChecker {
         }
 
         var baseParametersOk = true
-        val baseParameterTypes = (descriptor as? ClassDescriptor)?.defaultType?.substitutedUnderlyingTypes() ?: emptyList()
+        val baseParameterTypes = descriptor.defaultType.substitutedUnderlyingTypes()
 
         for ((baseParameter, baseParameterType) in primaryConstructor.valueParameters zip baseParameterTypes) {
             if (!isParameterAcceptableForInlineClass(baseParameter)) {

compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/IncrementalFirJvmCompilerRunner.kt

@@ -282,8 +282,7 @@ open class IncrementalFirJvmCompilerRunner(
                 allowNonCachedDeclarations = false,
                 useIrFakeOverrideBuilder = configuration.getBoolean(CommonConfigurationKeys.USE_IR_FAKE_OVERRIDE_BUILDER),
             )
-            val irGenerationExtensions =
+            val irGenerationExtensions = projectEnvironment.project.let { IrGenerationExtension.getInstances(it) }
-                (projectEnvironment as? VfsBasedProjectEnvironment)?.project?.let { IrGenerationExtension.getInstances(it) }.orEmpty()
             val (irModuleFragment, components, pluginContext, irActualizedResult) = cycleResult.convertToIrAndActualizeForJvm(
                 extensions, fir2IrConfiguration, irGenerationExtensions,
             )

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

@@ -120,9 +120,7 @@ class FlattenStringConcatenationLowering(val context: CommonBackendContext) : Fi
                 if (superQualifierSymbol != null)
                     return false
 
-                val function = symbol.owner as? IrSimpleFunction
+                val function = symbol.owner
-                    ?: return false
-
                 return function.isToString || function.isNullableToString
             }
 

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/jsAstUtils.kt

@@ -137,7 +137,7 @@ fun translateFunction(declaration: IrFunction, name: JsName?, context: JsGenerat
 
 private fun isFunctionTypeInvoke(receiver: JsExpression?, call: IrCall): Boolean {
     if (receiver == null || receiver is JsThisRef) return false
-    val simpleFunction = call.symbol.owner as? IrSimpleFunction ?: return false
+    val simpleFunction = call.symbol.owner
     val receiverType = simpleFunction.dispatchReceiverParameter?.type ?: return false
 
     if (call.origin === JsStatementOrigins.EXPLICIT_INVOKE) return false

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

@@ -22,7 +22,6 @@ import org.jetbrains.kotlin.ir.builders.irExprBody
 import org.jetbrains.kotlin.ir.declarations.IrClass
 import org.jetbrains.kotlin.ir.declarations.IrField
 import org.jetbrains.kotlin.ir.declarations.IrFile
-import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.expressions.IrCall
 import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.expressions.impl.IrGetFieldImpl
@@ -101,8 +100,8 @@ class EnumExternalEntriesLowering(private val context: JvmBackendContext) : File
     }
 
     override fun visitCall(expression: IrCall): IrExpression {
-        val owner = expression.symbol.owner as? IrSimpleFunction
+        val owner = expression.symbol.owner
-        val parentClass = owner?.parent as? IrClass ?: return super.visitCall(expression)
+        val parentClass = owner.parent as? IrClass ?: return super.visitCall(expression)
         val shouldBeLowered = owner.name == SpecialNames.ENUM_GET_ENTRIES && parentClass.isEnumClassWhichRequiresExternalEntries()
         if (!shouldBeLowered) return super.visitCall(expression)
         val field = state!!.getEntriesFieldForEnum(parentClass)

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

@@ -114,7 +114,7 @@ class JvmOptimizationLowering(val context: JvmBackendContext) : FileLoweringPass
         }
 
         private fun optimizePropertyAccess(expression: IrCall, data: IrDeclaration?): IrExpression {
-            val accessor = expression.symbol.owner as? IrSimpleFunction ?: return expression
+            val accessor = expression.symbol.owner
             if (accessor.modality != Modality.FINAL || accessor.isExternal) return expression
             val property = accessor.correspondingPropertySymbol?.owner ?: return expression
             if (property.isLateinit) return expression
@@ -357,9 +357,8 @@ class JvmOptimizationLowering(val context: JvmBackendContext) : FileLoweringPass
             when (statement) {
                 is IrDoWhileLoop -> {
                     // Expecting counter loop
-                    val doWhileLoop = statement as? IrDoWhileLoop ?: return null
+                    if (statement.origin != JvmLoweredStatementOrigin.DO_WHILE_COUNTER_LOOP) return null
-                    if (doWhileLoop.origin != JvmLoweredStatementOrigin.DO_WHILE_COUNTER_LOOP) return null
+                    val doWhileLoopBody = statement.body as? IrComposite ?: return null
-                    val doWhileLoopBody = doWhileLoop.body as? IrComposite ?: return null
                     if (doWhileLoopBody.origin != IrStatementOrigin.FOR_LOOP_INNER_WHILE) return null
                     val iterationInitialization = doWhileLoopBody.statements[0] as? IrComposite ?: return null
                     val loopVariableIndex = iterationInitialization.statements.indexOfFirst { it.isLoopVariable() }

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

@@ -51,7 +51,7 @@ class JvmPropertiesLowering(private val backendContext: JvmBackendContext) : IrE
     }
 
     override fun visitCall(expression: IrCall): IrExpression {
-        val simpleFunction = (expression.symbol.owner as? IrSimpleFunction) ?: return super.visitCall(expression)
+        val simpleFunction = expression.symbol.owner
         val property = simpleFunction.correspondingPropertySymbol?.owner ?: return super.visitCall(expression)
         expression.transformChildrenVoid()
 

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

@@ -39,7 +39,7 @@ class ResolveInlineCalls(val context: JvmBackendContext) : IrElementVisitorVoid,
         expression.acceptChildren(this, null)
 
         if (!expression.symbol.owner.isInlineFunctionCall(context)) return
-        val maybeFakeOverrideOfMultiFileBridge = expression.symbol.owner as? IrSimpleFunction ?: return
+        val maybeFakeOverrideOfMultiFileBridge = expression.symbol.owner
         val resolved =
             maybeFakeOverrideOfMultiFileBridge.resolveMultiFileFacadeMember() ?: maybeFakeOverrideOfMultiFileBridge.resolveFakeOverride()
             ?: return

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/GenericReturnTypeLowering.kt

@@ -8,20 +8,17 @@ package org.jetbrains.kotlin.backend.wasm.lower
 import org.jetbrains.kotlin.backend.common.FileLoweringPass
 import org.jetbrains.kotlin.backend.common.IrElementTransformerVoidWithContext
 import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
-import org.jetbrains.kotlin.backend.common.lower.irComposite
 import org.jetbrains.kotlin.backend.wasm.WasmBackendContext
 import org.jetbrains.kotlin.ir.backend.js.utils.erasedUpperBound
 import org.jetbrains.kotlin.ir.backend.js.utils.realOverrideTarget
 import org.jetbrains.kotlin.ir.builders.irImplicitCast
 import org.jetbrains.kotlin.ir.declarations.IrFile
-import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.expressions.IrCall
 import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.symbols.IrSymbol
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.util.defaultType
 import org.jetbrains.kotlin.ir.util.irCall
-import org.jetbrains.kotlin.ir.util.isTypeParameter
 import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
 
 /**
@@ -48,8 +45,7 @@ class GenericReturnTypeLowering(val context: WasmBackendContext) : FileLoweringP
     }
 
     private fun transformGenericCall(call: IrCall, scopeOwnerSymbol: IrSymbol): IrExpression {
-        val function: IrSimpleFunction =
+        val function = call.symbol.owner
-            call.symbol.owner as? IrSimpleFunction ?: return call
 
         val erasedReturnType: IrType =
             function.realOverrideTarget.returnType.eraseUpperBoundType()

compiler/ir/ir.interpreter/src/org/jetbrains/kotlin/ir/interpreter/preprocessor/IrInterpreterConstGetterPreprocessor.kt

@@ -11,7 +11,6 @@ import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.declarations.IrDeclarationOrigin
 import org.jetbrains.kotlin.ir.declarations.IrField
 import org.jetbrains.kotlin.ir.declarations.IrFunction
-import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.IrCompositeImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrGetObjectValueImpl
@@ -25,8 +24,7 @@ class IrInterpreterConstGetterPreprocessor : IrInterpreterPreprocessor {
     }
 
     override fun visitCall(expression: IrCall, data: IrInterpreterPreprocessorData): IrElement {
-        val function = (expression.symbol.owner as? IrSimpleFunction) ?: return super.visitCall(expression, data)
+        val field = expression.symbol.owner.correspondingPropertySymbol?.owner?.backingField ?: return super.visitCall(expression, data)
-        val field = function.correspondingPropertySymbol?.owner?.backingField ?: return super.visitCall(expression, data)
         return expression.lowerConstRead(field, data) ?: super.visitCall(expression, data)
     }
 

compiler/ir/ir.interpreter/src/org/jetbrains/kotlin/ir/interpreter/transformer/IrConstOnlyNecessaryTransformer.kt

@@ -11,7 +11,6 @@ import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.IrStatement
 import org.jetbrains.kotlin.ir.declarations.IrField
 import org.jetbrains.kotlin.ir.declarations.IrFile
-import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.interpreter.IrInterpreter
 import org.jetbrains.kotlin.ir.interpreter.checker.EvaluationMode
@@ -35,7 +34,7 @@ internal class IrConstOnlyNecessaryTransformer(
     interpreter, irFile, mode, checker, evaluatedConstTracker, inlineConstTracker, onWarning, onError, suppressExceptions
 ) {
     override fun visitCall(expression: IrCall, data: Data): IrElement {
-        val isConstGetter = (expression.symbol.owner as? IrSimpleFunction)?.correspondingPropertySymbol?.owner?.isConst == true
+        val isConstGetter = expression.symbol.owner.correspondingPropertySymbol?.owner?.isConst == true
         if (!data.inAnnotation && !isConstGetter) {
             expression.transformChildren(this, data)
             return expression

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

@@ -17,9 +17,9 @@ import org.jetbrains.kotlin.ir.builders.irImplicitCast
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.*
-import org.jetbrains.kotlin.ir.overrides.IrUnimplementedOverridesStrategy
 import org.jetbrains.kotlin.ir.overrides.FakeOverrideBuilderStrategy
 import org.jetbrains.kotlin.ir.overrides.IrFakeOverrideBuilder
+import org.jetbrains.kotlin.ir.overrides.IrUnimplementedOverridesStrategy
 import org.jetbrains.kotlin.ir.symbols.*
 import org.jetbrains.kotlin.ir.symbols.impl.IrPropertySymbolImpl
 import org.jetbrains.kotlin.ir.symbols.impl.IrSimpleFunctionSymbolImpl
@@ -28,11 +28,7 @@ import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.types.impl.IrSimpleTypeImpl
 import org.jetbrains.kotlin.ir.types.impl.makeTypeProjection
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
-import org.jetbrains.kotlin.name.ClassId
+import org.jetbrains.kotlin.name.*
-import org.jetbrains.kotlin.name.FqName
-import org.jetbrains.kotlin.name.Name
-import org.jetbrains.kotlin.name.SpecialNames
-import org.jetbrains.kotlin.name.StandardClassIds
 import org.jetbrains.kotlin.util.OperatorNameConventions
 import org.jetbrains.kotlin.utils.*
 import java.io.StringWriter
@@ -842,7 +838,7 @@ fun IrClass.addSimpleDelegatingConstructor(
         )
     }
 
-val IrCall.isSuspend get() = (symbol.owner as? IrSimpleFunction)?.isSuspend == true
+val IrCall.isSuspend get() = symbol.owner.isSuspend
 val IrFunctionReference.isSuspend get() = (symbol.owner as? IrSimpleFunction)?.isSuspend == true
 
 val IrFunction.isOverridable get() = this is IrSimpleFunction && this.isOverridable

compiler/light-classes/src/org/jetbrains/kotlin/asJava/classes/ultraLightField.kt

@@ -193,7 +193,7 @@ internal open class KtUltraLightFieldImpl protected constructor(
     override val lightMemberOrigin = LightMemberOriginForDeclaration(declaration, JvmDeclarationOriginKind.OTHER)
 
     override fun setName(@NonNls name: String): PsiElement {
-        (kotlinOrigin as? KtNamedDeclaration)?.setName(name)
+        kotlinOrigin.setName(name)
         return this
     }
 

core/descriptors.jvm/src/org/jetbrains/kotlin/load/java/lazy/types/RawSubstitution.kt

@@ -75,7 +75,7 @@ internal class RawSubstitution(typeParameterUpperBoundEraser: TypeParameterUpper
             },
             type.isMarkedNullable, memberScope
         ) factory@{ kotlinTypeRefiner ->
-            val classId = (declaration as? ClassDescriptor)?.classId ?: return@factory null
+            val classId = declaration.classId ?: return@factory null
 
             @OptIn(TypeRefinement::class)
             val refinedClassDescriptor = kotlinTypeRefiner.findClassAcrossModuleDependencies(classId) ?: return@factory null

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

@@ -7,23 +7,24 @@ package org.jetbrains.kotlin.backend.konan.descriptors
 
 import llvm.LLVMABIAlignmentOfType
 import llvm.LLVMABISizeOfType
-import llvm.LLVMPreferredAlignmentOfType
 import llvm.LLVMStoreSizeOfType
 import org.jetbrains.kotlin.backend.common.lower.coroutines.getOrCreateFunctionWithContinuationStub
 import org.jetbrains.kotlin.backend.konan.*
-import org.jetbrains.kotlin.backend.konan.ir.*
+import org.jetbrains.kotlin.backend.konan.ir.getSuperClassNotAny
+import org.jetbrains.kotlin.backend.konan.ir.isSpecialClassWithNoSupertypes
 import org.jetbrains.kotlin.backend.konan.llvm.CodegenLlvmHelpers
 import org.jetbrains.kotlin.backend.konan.llvm.computeFunctionName
-import org.jetbrains.kotlin.backend.konan.llvm.toLLVMType
 import org.jetbrains.kotlin.backend.konan.llvm.localHash
+import org.jetbrains.kotlin.backend.konan.llvm.toLLVMType
 import org.jetbrains.kotlin.backend.konan.lower.bridgeTarget
-import org.jetbrains.kotlin.backend.konan.serialization.KonanIrLinker
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.IrClassReference
 import org.jetbrains.kotlin.ir.expressions.IrConst
-import org.jetbrains.kotlin.ir.objcinterop.*
+import org.jetbrains.kotlin.ir.objcinterop.canObjCClassMethodBeCalledVirtually
+import org.jetbrains.kotlin.ir.objcinterop.isKotlinObjCClass
+import org.jetbrains.kotlin.ir.objcinterop.isObjCClassMethod
 import org.jetbrains.kotlin.ir.symbols.IrFieldSymbol
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.util.*
@@ -470,8 +471,7 @@ internal class ClassLayoutBuilder(val irClass: IrClass, val context: Context) {
         irClass.annotations.forEach {
             val irFile = irClass.fileOrNull
 
-            val annotationClass = (it.symbol.owner as? IrConstructor)?.constructedClass
+            val annotationClass = it.symbol.owner.constructedClass
-                    ?: error(irFile, it, "unexpected annotation")
 
             if (annotationClass.hasAnnotation(RuntimeNames.associatedObjectKey)) {
                 val argument = it.getValueArgument(0)

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

@@ -51,8 +51,6 @@ import org.jetbrains.kotlin.konan.library.KonanLibrary
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.native.interop.ObjCMethodInfo
-import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameUnsafe
-import org.jetbrains.kotlin.resolve.descriptorUtil.module
 
 internal class InteropLowering(generationState: NativeGenerationState) : FileLoweringPass {
     // TODO: merge these lowerings.
@@ -1034,11 +1032,7 @@ private class InteropTransformer(
         if (!function.isFromInteropLibrary()) return null
         if (!function.isGetter) return null
 
-        val constantProperty = (function as? IrSimpleFunction)
+        val constantProperty = function.correspondingPropertySymbol?.owner?.takeIf { it.isConst } ?: return null
-                ?.correspondingPropertySymbol
-                ?.owner
-                ?.takeIf { it.isConst }
-                ?: return null
 
         val initializer = constantProperty.backingField?.initializer?.expression
         require(initializer is IrConst<*>) { renderCompilerError(expression) }
@@ -1088,9 +1082,7 @@ private class InteropTransformer(
         builder.at(expression)
         val function = expression.symbol.owner
 
-        if ((function as? IrSimpleFunction)?.resolveFakeOverrideMaybeAbstract()?.symbol
+        if (function.resolveFakeOverrideMaybeAbstract()?.symbol == symbols.interopNativePointedRawPtrGetter) {
-                == symbols.interopNativePointedRawPtrGetter) {
-
             // Replace by the intrinsic call to be handled by code generator:
             return builder.irCall(symbols.interopNativePointedGetRawPointer).apply {
                 extensionReceiver = expression.dispatchReceiver

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

@@ -23,7 +23,6 @@ import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.objcinterop.*
 import org.jetbrains.kotlin.ir.util.*
-import org.jetbrains.kotlin.ir.util.irCall
 
 internal fun Context.getObjectClassInstanceFunction(clazz: IrClass) = mapping.objectInstanceGetter.getOrPut(clazz) {
     when {
@@ -159,8 +158,7 @@ internal class ObjectClassLowering(val generationState: NativeGenerationState) :
         val statements = this.body?.statements ?: return false
         if (statements.isEmpty()) return false
         val constructorCall = statements[0] as? IrDelegatingConstructorCall ?: return false
-        val constructor = constructorCall.symbol.owner as? IrConstructor ?: return false
+        if (!constructorCall.symbol.owner.constructedClass.isAny()) return false
-        if (!constructor.constructedClass.isAny()) return false
         return statements.asSequence().drop(1).all {
             it is IrBlock && it.origin == IrStatementOrigin.INITIALIZE_FIELD
         }

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

@@ -6,7 +6,6 @@
 package org.jetbrains.kotlin.backend.konan.lower
 
 import org.jetbrains.kotlin.backend.common.BodyLoweringPass
-import org.jetbrains.kotlin.backend.common.ir.Symbols
 import org.jetbrains.kotlin.backend.common.lower.at
 import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
 import org.jetbrains.kotlin.backend.konan.Context
@@ -83,7 +82,7 @@ internal class PostInlineLowering(val context: Context) : BodyLoweringPass {
                     val builder = StringBuilder()
                     args.elements.forEach {
                         require(it is IrConst<*>) { renderCompilerError(irFile, it, "expected const") }
-                        val value = (it as? IrConst<*>)?.value
+                        val value = it.value
                         require(value is Short && value >= 0 && value <= 0xff) {
                             renderCompilerError(irFile, it, "incorrect value for binary data: $value")
                         }

kotlin-native/utilities/cli-runner/src/main/kotlin/org/jetbrains/kotlin/cli/utilities/InteropCompiler.kt

@@ -31,8 +31,8 @@ fun invokeInterop(flavor: String, args: Array<String>, runFromDaemon: Boolean):
     val purgeUserLibs = arguments.purgeUserLibs
     val nopack = arguments.nopack
     val temporaryFilesDir = arguments.tempDir
-    val moduleName = (arguments as? CInteropArguments)?.moduleName
+    val moduleName = arguments.moduleName
-    val shortModuleName = (arguments as? CInteropArguments)?.shortModuleName
+    val shortModuleName = arguments.shortModuleName
 
     val buildDir = File("$outputFileName-build")
     val generatedDir = File(buildDir, "kotlin")

plugins/kapt3/kapt3-compiler/src/org/jetbrains/kotlin/kapt3/stubs/ClassFileToSourceStubConverter.kt

@@ -339,8 +339,16 @@ class ClassFileToSourceStubConverter(val kaptContext: KaptContextForStubGenerati
         if (!checkIfValidTypeName(clazz, Type.getObjectType(clazz.name))) return null
 
         val descriptor = kaptContext.origins[clazz]?.descriptor ?: return null
-        val isNested = (descriptor as? ClassDescriptor)?.isNested ?: false
+
-        val isInner = isNested && (descriptor as? ClassDescriptor)?.isInner ?: false
+        val isNested: Boolean
+        val isInner: Boolean
+        if (descriptor is ClassDescriptor) {
+            isNested = descriptor.isNested
+            isInner = isNested && descriptor.isInner
+        } else {
+            isNested = false
+            isInner = false
+        }
 
         val flags = getClassAccessFlags(clazz, descriptor, isInner, isNested)