diff --git a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/IrElementTransformerVoidWithContext.kt b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/IrElementTransformerVoidWithContext.kt
index bc686876b8f..5768a82c021 100644
--- a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/IrElementTransformerVoidWithContext.kt
+++ b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/IrElementTransformerVoidWithContext.kt
@@ -35,6 +35,21 @@ abstract class IrElementTransformerVoidWithContext : IrElementTransformerVoid()
     protected open fun createScope(declaration: IrSymbolOwner): ScopeWithIr =
         ScopeWithIr(Scope(declaration.symbol), declaration)
 
+    protected fun unsafeEnterScope(declaration: IrSymbolOwner) {
+        scopeStack.push(createScope(declaration))
+    }
+
+    protected fun unsafeLeaveScope() {
+        scopeStack.pop()
+    }
+
+    protected inline fun <T> withinScope(declaration: IrSymbolOwner, fn: () -> T): T {
+        unsafeEnterScope(declaration)
+        val result = fn()
+        unsafeLeaveScope()
+        return result
+    }
+
     final override fun visitFile(declaration: IrFile): IrFile {
         scopeStack.push(createScope(declaration))
         val result = visitFileNew(declaration)
diff --git a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/TailrecLowering.kt b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/TailrecLowering.kt
index 02e56b2065a..8461839f575 100644
--- a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/TailrecLowering.kt
+++ b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/TailrecLowering.kt
@@ -51,13 +51,17 @@ open class TailrecLowering(val context: BackendContext) : BodyLoweringPass {
                     element.acceptChildrenVoid(this)
                 }
 
-                override fun visitFunction(declaration: IrFunction) {
+                override fun visitSimpleFunction(declaration: IrSimpleFunction) {
                     declaration.acceptChildrenVoid(this)
-                    lowerTailRecursionCalls(declaration)
+                    if (declaration.isTailrec) {
+                        lowerTailRecursionCalls(declaration)
+                    }
                 }
             })
 
-            lowerTailRecursionCalls(container)
+            if (container is IrSimpleFunction && container.isTailrec) {
+                lowerTailRecursionCalls(container)
+            }
         }
     }
 
@@ -110,6 +114,9 @@ private fun TailrecLowering.lowerTailRecursionCalls(irFunction: IrFunction) {
             }
         }
     }.statements
+
+    // TODO BodyTransformer creates temporary variables with wrong parents in nested functions
+    oldBody.patchDeclarationParents(irFunction)
 }
 
 private class BodyTransformer(
diff --git a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/JvmLower.kt b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/JvmLower.kt
index d42c8338be9..096f349e5f3 100644
--- a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/JvmLower.kt
+++ b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/JvmLower.kt
@@ -19,20 +19,34 @@ import org.jetbrains.kotlin.descriptors.DescriptorVisibility
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.symbols.IrValueSymbol
-import org.jetbrains.kotlin.ir.util.PatchDeclarationParentsVisitor
-import org.jetbrains.kotlin.ir.util.isAnonymousObject
-import org.jetbrains.kotlin.ir.util.parentAsClass
+import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid
 import org.jetbrains.kotlin.ir.visitors.acceptChildrenVoid
 import org.jetbrains.kotlin.ir.visitors.acceptVoid
 import org.jetbrains.kotlin.load.java.JavaDescriptorVisibilities
 import org.jetbrains.kotlin.name.NameUtils
 
-private fun makePatchParentsPhase(number: Int): NamedCompilerPhase<CommonBackendContext, IrFile> = makeIrFilePhase(
-    { PatchDeclarationParents() },
-    name = "PatchParents$number",
-    description = "Patch parent references in IrFile, pass $number",
-)
+private var patchParentPhases = 0
+
+private fun makePatchParentsPhase(): NamedCompilerPhase<CommonBackendContext, IrFile> {
+    val number = patchParentPhases++
+    return makeIrFilePhase(
+        { PatchDeclarationParents() },
+        name = "PatchParents$number",
+        description = "Patch parent references in IrFile, pass $number",
+    )
+}
+
+private var checkParentPhases = 0
+
+private fun makeCheckParentsPhase(): NamedCompilerPhase<CommonBackendContext, IrFile> {
+    val number = checkParentPhases++
+    return makeIrFilePhase(
+        { CheckDeclarationParents() },
+        name = "CheckParents$number",
+        description = "Check parent references in IrFile, pass $number",
+    )
+}
 
 private class PatchDeclarationParents : FileLoweringPass {
     override fun lower(irFile: IrFile) {
@@ -40,6 +54,39 @@ private class PatchDeclarationParents : FileLoweringPass {
     }
 }
 
+private class CheckDeclarationParents : FileLoweringPass {
+    override fun lower(irFile: IrFile) {
+        val checker = CheckDeclarationParentsVisitor()
+        irFile.acceptVoid(checker)
+        if (checker.errors.isNotEmpty()) {
+            val expectedParents = LinkedHashSet<IrDeclarationParent>()
+            throw AssertionError(
+                buildString {
+                    append("Declarations with wrong parent: ")
+                    append(checker.errors.size)
+                    append("\n")
+                    checker.errors.forEach {
+                        append("declaration: ")
+                        append(it.declaration.render())
+                        append("\n\t")
+                        append(it.declaration)
+                        append("\nexpectedParent: ")
+                        append(it.expectedParent.render())
+                        append("\nactualParent: ")
+                        append(it.actualParent?.render())
+                        append("\n")
+                        expectedParents.add(it.expectedParent)
+                    }
+                    append("\nExpected parents:\n")
+                    expectedParents.forEach {
+                        append(it.dump())
+                    }
+                }
+            )
+        }
+    }
+}
+
 private val validateIrBeforeLowering = makeCustomPhase(
     ::validateIr,
     name = "ValidateIrBeforeLowering",
@@ -291,7 +338,7 @@ private val jvmFilePhases = listOf(
     singleAbstractMethodPhase,
     jvmInlineClassPhase,
     tailrecPhase,
-    makePatchParentsPhase(1),
+    // makePatchParentsPhase(),
 
     enumWhenPhase,
     singletonReferencesPhase,
@@ -300,7 +347,7 @@ private val jvmFilePhases = listOf(
     returnableBlocksPhase,
     sharedVariablesPhase,
     localDeclarationsPhase,
-    makePatchParentsPhase(2),
+    // makePatchParentsPhase(),
 
     jvmLocalClassExtractionPhase,
     staticCallableReferencePhase,
@@ -316,6 +363,7 @@ private val jvmFilePhases = listOf(
     defaultArgumentInjectorPhase,
     defaultArgumentCleanerPhase,
 
+    // makePatchParentsPhase(),
     interfacePhase,
     inheritedDefaultMethodsOnClassesPhase,
     replaceDefaultImplsOverriddenSymbolsPhase,
@@ -331,7 +379,7 @@ private val jvmFilePhases = listOf(
     innerClassesMemberBodyPhase,
     innerClassConstructorCallsPhase,
 
-    makePatchParentsPhase(3),
+    // makePatchParentsPhase(),
 
     enumClassPhase,
     objectClassPhase,
@@ -357,7 +405,7 @@ private val jvmFilePhases = listOf(
     renameFieldsPhase,
     fakeInliningLocalVariablesLowering,
 
-    makePatchParentsPhase(4)
+    // makePatchParentsPhase()
 )
 
 val jvmLoweringPhases = NamedCompilerPhase(
diff --git a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/AnonymousObjectSuperConstructorLowering.kt b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/AnonymousObjectSuperConstructorLowering.kt
index 3b0e95726e3..fa4f9698792 100644
--- a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/AnonymousObjectSuperConstructorLowering.kt
+++ b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/AnonymousObjectSuperConstructorLowering.kt
@@ -22,6 +22,7 @@ import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.IrConstructorCallImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrGetValueImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrTypeOperatorCallImpl
+import org.jetbrains.kotlin.ir.util.patchDeclarationParents
 import org.jetbrains.kotlin.ir.util.transformInPlace
 
 internal val anonymousObjectSuperConstructorPhase = makeIrFilePhase(
@@ -124,8 +125,10 @@ private class AnonymousObjectSuperConstructorLowering(val context: JvmBackendCon
                     // Avoid complex expressions between `new` and `<init>`, as the inliner gets confused if
                     // an argument to `<init>` is an anonymous object. Put them in variables instead.
                     // See KT-21781 for an example; in short, it looks like `object : S({ ... })` in an inline function.
-                    for ((i, argument) in newArguments.withIndex())
+                    for ((i, argument) in newArguments.withIndex()) {
+                        argument.patchDeclarationParents(currentDeclarationParent)
                         putValueArgument(i + objectConstructorCall.valueArgumentsCount, irGet(irTemporary(argument)))
+                    }
                 }
             }
         }
diff --git a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/AssertionLowering.kt b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/AssertionLowering.kt
index f0bd18c1b00..dea7c0a2143 100644
--- a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/AssertionLowering.kt
+++ b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/AssertionLowering.kt
@@ -17,10 +17,7 @@ import org.jetbrains.kotlin.config.JVMAssertionsMode
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.IrStatement
 import org.jetbrains.kotlin.ir.builders.*
-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.IrFunction
+import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.IrCall
 import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.expressions.impl.IrCompositeImpl
@@ -45,16 +42,25 @@ private class AssertionLowering(private val context: JvmBackendContext) :
     // assertions when compiled with -Xassertions=jvm.
     class ClassInfo(val irClass: IrClass, val topLevelClass: IrClass, var assertionsDisabledField: IrField? = null)
 
+    private val scopeOwnerStack = java.util.ArrayDeque<IrDeclaration>()
+
     override fun lower(irFile: IrFile) {
         // In legacy mode we treat assertions as inline function calls
         if (context.state.assertionsMode != JVMAssertionsMode.LEGACY)
             irFile.transformChildren(this, null)
     }
 
+    override fun visitDeclaration(declaration: IrDeclarationBase, data: ClassInfo?): IrStatement {
+        scopeOwnerStack.push(declaration)
+        val result = super.visitDeclaration(declaration, data)
+        scopeOwnerStack.pop()
+        return result
+    }
+
     override fun visitClass(declaration: IrClass, data: ClassInfo?): IrStatement {
         val info = ClassInfo(declaration, data?.topLevelClass ?: declaration)
 
-        super.visitClass(declaration, info)
+        visitDeclaration(declaration, info)
 
         // Note that it's necessary to add this member at the beginning of the class, before all user-visible
         // initializers, which may contain assertions. At the same time, assertions are supposed to be enabled
@@ -77,7 +83,7 @@ private class AssertionLowering(private val context: JvmBackendContext) :
         if (mode == JVMAssertionsMode.ALWAYS_DISABLE)
             return IrCompositeImpl(expression.startOffset, expression.endOffset, context.irBuiltIns.unitType)
 
-        context.createIrBuilder(expression.symbol).run {
+        context.createIrBuilder(scopeOwnerStack.peek().symbol).run {
             at(expression)
             val assertCondition = expression.getValueArgument(0)!!
             val lambdaArgument = if (function.valueParameters.size == 2) expression.getValueArgument(1) else null
diff --git a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/FunctionReferenceLowering.kt b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/FunctionReferenceLowering.kt
index 2b541aa4fb0..c1a3c8d12e8 100644
--- a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/FunctionReferenceLowering.kt
+++ b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/FunctionReferenceLowering.kt
@@ -1021,7 +1021,7 @@ internal class FunctionReferenceLowering(private val context: JvmBackendContext)
             inlinedAdapterBlock.statements.add(inlinedAdapterResult)
 
             callee.body = null
-            return inlinedAdapterBlock
+            return inlinedAdapterBlock.patchDeclarationParents(invokeMethod)
         }
 
         private fun buildOverride(superFunction: IrSimpleFunction, newReturnType: IrType = superFunction.returnType): IrSimpleFunction =
diff --git a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/InterfaceLowering.kt b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/InterfaceLowering.kt
index cb525af0902..69103193c36 100644
--- a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/InterfaceLowering.kt
+++ b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/InterfaceLowering.kt
@@ -184,7 +184,6 @@ internal class InterfaceLowering(val context: JvmBackendContext) : IrElementTran
             irClass.declarations.remove(field)
             defaultImplsIrClass.declarations.add(0, field)
             field.parent = defaultImplsIrClass
-            field.initializer?.patchDeclarationParents(defaultImplsIrClass)
         }
     }
 
diff --git a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/JvmInlineClassLowering.kt b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/JvmInlineClassLowering.kt
index 3379bbc0cc3..0a3d7af27d2 100644
--- a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/JvmInlineClassLowering.kt
+++ b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/JvmInlineClassLowering.kt
@@ -78,7 +78,9 @@ private class JvmInlineClassLowering(private val context: JvmBackendContext) : F
 
         declaration.transformDeclarationsFlat { memberDeclaration ->
             if (memberDeclaration is IrFunction) {
-                transformFunctionFlat(memberDeclaration)
+                withinScope(memberDeclaration) {
+                    transformFunctionFlat(memberDeclaration)
+                }
             } else {
                 memberDeclaration.accept(this, null)
                 null
@@ -134,7 +136,10 @@ private class JvmInlineClassLowering(private val context: JvmBackendContext) : F
     }
 
     private fun transformSimpleFunctionFlat(function: IrSimpleFunction, replacement: IrSimpleFunction): List<IrDeclaration> {
-        replacement.valueParameters.forEach { it.transformChildrenVoid() }
+        replacement.valueParameters.forEach {
+            it.transformChildrenVoid()
+            it.defaultValue?.patchDeclarationParents(replacement)
+        }
         allScopes.push(createScope(function))
         replacement.body = function.body?.transform(this, null)?.patchDeclarationParents(replacement)
         allScopes.pop()
diff --git a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/MainMethodGenerationLowering.kt b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/MainMethodGenerationLowering.kt
index 03a733beb6e..a2a4b9b6577 100644
--- a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/MainMethodGenerationLowering.kt
+++ b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/MainMethodGenerationLowering.kt
@@ -78,17 +78,17 @@ private class MainMethodGenerationLowering(private val context: JvmBackendContex
 
         irClass.functions.find { it.isMainMethod() }?.let { mainMethod ->
             if (mainMethod.isSuspend) {
-                irClass.generateMainMethod { args ->
-                    +irRunSuspend(mainMethod, args)
+                irClass.generateMainMethod { newMain, args ->
+                    +irRunSuspend(mainMethod, args, newMain)
                 }
             }
             return
         }
 
         irClass.functions.find { it.isParameterlessMainMethod() }?.let { parameterlessMainMethod ->
-            irClass.generateMainMethod {
+            irClass.generateMainMethod { newMain, _ ->
                 if (parameterlessMainMethod.isSuspend) {
-                    +irRunSuspend(parameterlessMainMethod, null)
+                    +irRunSuspend(parameterlessMainMethod, null, newMain)
                 } else {
                     +irCall(parameterlessMainMethod)
                 }
@@ -104,7 +104,7 @@ private class MainMethodGenerationLowering(private val context: JvmBackendContex
                 name.asString() == "main"
 
     private fun IrSimpleFunction.isMainMethod(): Boolean {
-        if (getJvmNameFromAnnotation() ?: name.asString() != "main") return false
+        if ((getJvmNameFromAnnotation() ?: name.asString()) != "main") return false
         if (!returnType.isUnit()) return false
 
         val parameter = allParameters.singleOrNull() ?: return false
@@ -119,7 +119,7 @@ private class MainMethodGenerationLowering(private val context: JvmBackendContex
         }
     }
 
-    private fun IrClass.generateMainMethod(makeBody: IrBlockBodyBuilder.(IrValueParameter) -> Unit) =
+    private fun IrClass.generateMainMethod(makeBody: IrBlockBodyBuilder.(IrSimpleFunction, IrValueParameter) -> Unit) =
         addFunction {
             name = Name.identifier("main")
             visibility = DescriptorVisibilities.PUBLIC
@@ -131,10 +131,14 @@ private class MainMethodGenerationLowering(private val context: JvmBackendContex
                 name = Name.identifier("args")
                 type = context.irBuiltIns.arrayClass.typeWith(context.irBuiltIns.stringType)
             }
-            body = context.createIrBuilder(symbol).irBlockBody { makeBody(args) }
+            body = context.createIrBuilder(symbol).irBlockBody { makeBody(this@apply, args) }
         }
 
-    private fun IrBuilderWithScope.irRunSuspend(target: IrSimpleFunction, args: IrValueParameter?): IrExpression {
+    private fun IrBuilderWithScope.irRunSuspend(
+        target: IrSimpleFunction,
+        args: IrValueParameter?,
+        newMain: IrSimpleFunction
+    ): IrExpression {
         val backendContext = this@MainMethodGenerationLowering.context
         return irBlock {
             val wrapperConstructor = backendContext.irFactory.buildClass {
@@ -152,7 +156,7 @@ private class MainMethodGenerationLowering(private val context: JvmBackendContex
 
                 wrapper.superTypes += lambdaSuperClass.defaultType
                 wrapper.superTypes += functionClass.typeWith(backendContext.irBuiltIns.anyNType)
-                wrapper.parent = target.parent
+                wrapper.parent = newMain
 
                 val stringArrayType = backendContext.irBuiltIns.arrayClass.typeWith(backendContext.irBuiltIns.stringType)
                 val argsField = args?.let {
diff --git a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/MappedEnumWhenLowering.kt b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/MappedEnumWhenLowering.kt
index bbbc402ea92..0290b7fa631 100644
--- a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/MappedEnumWhenLowering.kt
+++ b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/MappedEnumWhenLowering.kt
@@ -127,7 +127,6 @@ private class MappedEnumWhenLowering(context: JvmBackendContext) : EnumWhenLower
         super.visitClassNew(declaration)
 
         for ((enum, mapping) in mappingState.mappings) {
-            val builder = context.createIrBuilder(mappingState.mappingsClass.symbol)
             val enumValues = enum.functions.single {
                 it.name.toString() == "values"
                         && it.dispatchReceiverParameter == null
@@ -136,6 +135,7 @@ private class MappedEnumWhenLowering(context: JvmBackendContext) : EnumWhenLower
                         && it.returnType.isBoxedArray
                         && it.returnType.getArrayElementType(context.irBuiltIns).classOrNull == enum.symbol
             }
+            val builder = context.createIrBuilder(mapping.field.symbol)
             mapping.field.initializer = builder.irExprBody(builder.irBlock {
                 val enumSize = irCall(refArraySize).apply { dispatchReceiver = irCall(enumValues) }
                 val result = irTemporary(irCall(intArrayConstructor).apply { putValueArgument(0, enumSize) })
diff --git a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/PropertyReferenceLowering.kt b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/PropertyReferenceLowering.kt
index 5685fc8fdc1..04b31bfde5f 100644
--- a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/PropertyReferenceLowering.kt
+++ b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/PropertyReferenceLowering.kt
@@ -238,7 +238,7 @@ internal class PropertyReferenceLowering(val context: JvmBackendContext) : IrEle
         if (data.kProperties.isNotEmpty()) {
             declaration.declarations.add(0, data.kPropertiesField.apply {
                 parent = declaration
-                initializer = context.createJvmIrBuilder(declaration.symbol).run {
+                initializer = context.createJvmIrBuilder(data.kPropertiesField.symbol).run {
                     val initializers = data.kProperties.values.sortedBy { it.index }.map { it.initializer }
                     irExprBody(irArrayOf(kPropertiesFieldType, initializers))
                 }
diff --git a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/ScriptLowering.kt b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/ScriptLowering.kt
index d3690e35720..16a685da26a 100644
--- a/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/ScriptLowering.kt
+++ b/compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/ScriptLowering.kt
@@ -76,6 +76,8 @@ private class ScriptsToClassesLowering(val context: JvmBackendContext, val inner
 
         for ((irScript, irScriptClass) in scriptsToClasses) {
             finalizeScriptClass(irScriptClass, irScript, symbolRemapper)
+            // TODO fix parents in script classes
+            irScriptClass.patchDeclarationParents(irScript.parent)
         }
     }
 
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/PatchDeclarationParents.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/PatchDeclarationParents.kt
index 4bfa8916e3e..520d87d136a 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/PatchDeclarationParents.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/PatchDeclarationParents.kt
@@ -6,14 +6,12 @@
 package org.jetbrains.kotlin.ir.util
 
 import org.jetbrains.kotlin.ir.IrElement
-import org.jetbrains.kotlin.ir.declarations.IrDeclaration
-import org.jetbrains.kotlin.ir.declarations.IrDeclarationParent
-import org.jetbrains.kotlin.ir.declarations.IrPackageFragment
-import org.jetbrains.kotlin.ir.declarations.IrDeclarationBase
+import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid
 import org.jetbrains.kotlin.ir.visitors.acceptChildrenVoid
 import org.jetbrains.kotlin.ir.visitors.acceptVoid
 import java.util.*
+import kotlin.collections.ArrayList
 
 fun <T : IrElement> T.patchDeclarationParents(initialParent: IrDeclarationParent? = null) =
     apply {
@@ -57,3 +55,54 @@ class PatchDeclarationParentsVisitor() : IrElementVisitorVoid {
         declaration.parent = declarationParentsStack.peekFirst()
     }
 }
+
+
+class CheckDeclarationParentsVisitor() : IrElementVisitorVoid {
+
+    constructor(containingDeclaration: IrDeclarationParent) : this() {
+        declarationParentsStack.push(containingDeclaration)
+    }
+
+    private val declarationParentsStack = ArrayDeque<IrDeclarationParent>()
+
+    class Data(val declaration: IrDeclaration, val expectedParent: IrDeclarationParent, val actualParent: IrDeclarationParent?)
+
+    val errors = ArrayList<Data>()
+
+    override fun visitElement(element: IrElement) {
+        element.acceptChildrenVoid(this)
+    }
+
+    override fun visitPackageFragment(declaration: IrPackageFragment) {
+        declarationParentsStack.push(declaration)
+        super.visitPackageFragment(declaration)
+        declarationParentsStack.pop()
+    }
+
+    override fun visitDeclaration(declaration: IrDeclarationBase) {
+        checkParent(declaration)
+
+        if (declaration is IrDeclarationParent) {
+            declarationParentsStack.push(declaration)
+        }
+
+        super.visitDeclaration(declaration)
+
+        if (declaration is IrDeclarationParent) {
+            declarationParentsStack.pop()
+        }
+    }
+
+    private fun checkParent(declaration: IrDeclaration) {
+        val expectedParent = declarationParentsStack.peekFirst()
+        try {
+            val actualParent = declaration.parent
+            if (actualParent != expectedParent) {
+                errors.add(Data(declaration, expectedParent, actualParent))
+            }
+        } catch (e: Exception) {
+            errors.add(Data(declaration, expectedParent, null))
+        }
+
+    }
+}