diff --git a/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrImplicitCastInserter.kt b/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrImplicitCastInserter.kt
index dc07ee5d493..ebe7c9e559f 100644
--- a/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrImplicitCastInserter.kt
+++ b/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrImplicitCastInserter.kt
@@ -274,11 +274,7 @@ class Fir2IrImplicitCastInserter(
     }
 
     override fun visitExpressionWithSmartcast(expressionWithSmartcast: FirExpressionWithSmartcast, data: IrElement): IrExpression {
-        return if (expressionWithSmartcast.smartcastStability == SmartcastStability.STABLE_VALUE) {
-            implicitCastOrExpression(data as IrExpression, expressionWithSmartcast.typeRef)
-        } else {
-            data as IrExpression
-        }
+        return implicitCastOrExpression(data as IrExpression, expressionWithSmartcast.typeRef)
     }
 
     override fun visitExpressionWithSmartcastToNull(
diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/ResolveUtils.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/ResolveUtils.kt
index 2c5e8b5ec2b..29420ee9e93 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/ResolveUtils.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/ResolveUtils.kt
@@ -36,7 +36,6 @@ import org.jetbrains.kotlin.fir.types.builder.buildResolvedTypeRef
 import org.jetbrains.kotlin.fir.types.impl.ConeClassLikeTypeImpl
 import org.jetbrains.kotlin.name.*
 import org.jetbrains.kotlin.resolve.ForbiddenNamedArgumentsTarget
-import org.jetbrains.kotlin.types.SmartcastStability
 
 fun List<FirQualifierPart>.toTypeProjections(): Array<ConeTypeProjection> =
     asReversed().flatMap { it.typeArgumentList.typeArguments.map { typeArgument -> typeArgument.toConeTypeProjection() } }.toTypedArray()
@@ -286,9 +285,8 @@ fun BodyResolveComponents.transformQualifiedAccessUsingSmartcastInfo(
     }
     return buildExpressionWithSmartcast {
         originalExpression = qualifiedAccessExpression
-        smartcastType = intersectedTypeRef
+        typeRef = intersectedTypeRef
         this.typesFromSmartCast = typesFromSmartCast
-        smartcastStability = SmartcastStability.STABLE_VALUE
     }
 }
 
diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/FirReceivers.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/FirReceivers.kt
index 295a7d69eeb..0ce7b7d1813 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/FirReceivers.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/FirReceivers.kt
@@ -27,7 +27,6 @@ import org.jetbrains.kotlin.fir.types.ConeKotlinType
 import org.jetbrains.kotlin.fir.types.builder.buildResolvedTypeRef
 import org.jetbrains.kotlin.fir.types.coneType
 import org.jetbrains.kotlin.fir.types.coneTypeSafe
-import org.jetbrains.kotlin.types.SmartcastStability
 
 interface Receiver
 
@@ -90,9 +89,8 @@ sealed class ImplicitReceiverValue<S : AbstractFirBasedSymbol<*>>(
         } else {
             buildExpressionWithSmartcast {
                 originalExpression = originalReceiverExpression
-                smartcastType = originalReceiverExpression.typeRef.resolvedTypeFromPrototype(type)
+                typeRef = originalReceiverExpression.typeRef.resolvedTypeFromPrototype(type)
                 typesFromSmartCast = listOf(type)
-                smartcastStability = SmartcastStability.STABLE_VALUE
             }
         }
         implicitScope = type.scope(useSiteSession, scopeSession, FakeOverrideTypeCalculator.DoNothing)
diff --git a/compiler/fir/tree/gen/org/jetbrains/kotlin/fir/expressions/FirExpressionWithSmartcast.kt b/compiler/fir/tree/gen/org/jetbrains/kotlin/fir/expressions/FirExpressionWithSmartcast.kt
index dded469518b..a2fbdc5dcea 100644
--- a/compiler/fir/tree/gen/org/jetbrains/kotlin/fir/expressions/FirExpressionWithSmartcast.kt
+++ b/compiler/fir/tree/gen/org/jetbrains/kotlin/fir/expressions/FirExpressionWithSmartcast.kt
@@ -11,7 +11,6 @@ import org.jetbrains.kotlin.fir.references.FirReference
 import org.jetbrains.kotlin.fir.types.ConeKotlinType
 import org.jetbrains.kotlin.fir.types.FirTypeProjection
 import org.jetbrains.kotlin.fir.types.FirTypeRef
-import org.jetbrains.kotlin.types.SmartcastStability
 import org.jetbrains.kotlin.fir.visitors.*
 import org.jetbrains.kotlin.fir.FirImplementationDetail
 
@@ -32,8 +31,6 @@ abstract class FirExpressionWithSmartcast : FirQualifiedAccessExpression() {
     abstract val originalExpression: FirQualifiedAccessExpression
     abstract val typesFromSmartCast: Collection<ConeKotlinType>
     abstract val originalType: FirTypeRef
-    abstract val smartcastType: FirTypeRef
-    abstract val smartcastStability: SmartcastStability
 
     override fun <R, D> accept(visitor: FirVisitor<R, D>, data: D): R = visitor.visitExpressionWithSmartcast(this, data)
 
diff --git a/compiler/fir/tree/gen/org/jetbrains/kotlin/fir/expressions/FirExpressionWithSmartcastToNull.kt b/compiler/fir/tree/gen/org/jetbrains/kotlin/fir/expressions/FirExpressionWithSmartcastToNull.kt
index 9181ab521fb..3e643586063 100644
--- a/compiler/fir/tree/gen/org/jetbrains/kotlin/fir/expressions/FirExpressionWithSmartcastToNull.kt
+++ b/compiler/fir/tree/gen/org/jetbrains/kotlin/fir/expressions/FirExpressionWithSmartcastToNull.kt
@@ -11,7 +11,6 @@ import org.jetbrains.kotlin.fir.references.FirReference
 import org.jetbrains.kotlin.fir.types.ConeKotlinType
 import org.jetbrains.kotlin.fir.types.FirTypeProjection
 import org.jetbrains.kotlin.fir.types.FirTypeRef
-import org.jetbrains.kotlin.types.SmartcastStability
 import org.jetbrains.kotlin.fir.visitors.*
 import org.jetbrains.kotlin.fir.FirImplementationDetail
 
@@ -32,8 +31,6 @@ abstract class FirExpressionWithSmartcastToNull : FirExpressionWithSmartcast() {
     abstract override val originalExpression: FirQualifiedAccessExpression
     abstract override val typesFromSmartCast: Collection<ConeKotlinType>
     abstract override val originalType: FirTypeRef
-    abstract override val smartcastType: FirTypeRef
-    abstract override val smartcastStability: SmartcastStability
 
     override fun <R, D> accept(visitor: FirVisitor<R, D>, data: D): R = visitor.visitExpressionWithSmartcastToNull(this, data)
 
diff --git a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/builder/FirExpressionWithSmartcastBuilder.kt b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/builder/FirExpressionWithSmartcastBuilder.kt
index faa0b3f8c65..48d595c654d 100644
--- a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/builder/FirExpressionWithSmartcastBuilder.kt
+++ b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/builder/FirExpressionWithSmartcastBuilder.kt
@@ -10,16 +10,14 @@ import org.jetbrains.kotlin.fir.expressions.FirQualifiedAccessExpression
 import org.jetbrains.kotlin.fir.expressions.impl.FirExpressionWithSmartcastImpl
 import org.jetbrains.kotlin.fir.types.ConeKotlinType
 import org.jetbrains.kotlin.fir.types.FirTypeRef
-import org.jetbrains.kotlin.types.SmartcastStability
 
 class FirExpressionWithSmartcastBuilder {
     lateinit var originalExpression: FirQualifiedAccessExpression
-    lateinit var smartcastType: FirTypeRef
+    lateinit var typeRef: FirTypeRef
     lateinit var typesFromSmartCast: Collection<ConeKotlinType>
-    lateinit var smartcastStability: SmartcastStability
 
     fun build(): FirExpressionWithSmartcast {
-        return FirExpressionWithSmartcastImpl(originalExpression, smartcastType, typesFromSmartCast, smartcastStability)
+        return FirExpressionWithSmartcastImpl(originalExpression, typeRef, typesFromSmartCast)
     }
 }
 
diff --git a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/builder/FirExpressionWithSmartcastToNullBuilder.kt b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/builder/FirExpressionWithSmartcastToNullBuilder.kt
index 4d3df9a28b6..b639f24c92d 100644
--- a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/builder/FirExpressionWithSmartcastToNullBuilder.kt
+++ b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/builder/FirExpressionWithSmartcastToNullBuilder.kt
@@ -10,16 +10,14 @@ import org.jetbrains.kotlin.fir.expressions.FirQualifiedAccessExpression
 import org.jetbrains.kotlin.fir.expressions.impl.FirExpressionWithSmartcastToNullImpl
 import org.jetbrains.kotlin.fir.types.ConeKotlinType
 import org.jetbrains.kotlin.fir.types.FirTypeRef
-import org.jetbrains.kotlin.types.SmartcastStability
 
 class FirExpressionWithSmartcastToNullBuilder {
     lateinit var originalExpression: FirQualifiedAccessExpression
-    lateinit var smartcastType: FirTypeRef
+    lateinit var typeRef: FirTypeRef
     lateinit var typesFromSmartCast: Collection<ConeKotlinType>
-    lateinit var smartcastStability: SmartcastStability
 
     fun build(): FirExpressionWithSmartcastToNull {
-        return FirExpressionWithSmartcastToNullImpl(originalExpression, smartcastType, typesFromSmartCast, smartcastStability)
+        return FirExpressionWithSmartcastToNullImpl(originalExpression, typeRef, typesFromSmartCast)
     }
 }
 
diff --git a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/impl/FirExpressionWithSmartcastImpl.kt b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/impl/FirExpressionWithSmartcastImpl.kt
index 792c18878d5..19b1cac569c 100644
--- a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/impl/FirExpressionWithSmartcastImpl.kt
+++ b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/impl/FirExpressionWithSmartcastImpl.kt
@@ -19,13 +19,11 @@ import org.jetbrains.kotlin.fir.types.FirTypeRef
 import org.jetbrains.kotlin.fir.visitors.FirTransformer
 import org.jetbrains.kotlin.fir.visitors.FirVisitor
 import org.jetbrains.kotlin.fir.visitors.transformSingle
-import org.jetbrains.kotlin.types.SmartcastStability
 
 internal class FirExpressionWithSmartcastImpl(
     override var originalExpression: FirQualifiedAccessExpression,
-    override val smartcastType: FirTypeRef,
-    override val typesFromSmartCast: Collection<ConeKotlinType>,
-    override val smartcastStability: SmartcastStability
+    override val typeRef: FirTypeRef,
+    override val typesFromSmartCast: Collection<ConeKotlinType>
 ) : FirExpressionWithSmartcast() {
     init {
         assert(originalExpression.typeRef is FirResolvedTypeRef)
@@ -39,10 +37,6 @@ internal class FirExpressionWithSmartcastImpl(
     override val extensionReceiver: FirExpression get() = originalExpression.extensionReceiver
     override val calleeReference: FirReference get() = originalExpression.calleeReference
     override val originalType: FirTypeRef get() = originalExpression.typeRef
-    // A FirExpressionWithSmartcast is only an effective smartcast if `smartcastStability == SmartcastStability.STABLE_VALUE`. Otherwise,
-    // it's the same as the `originalExpression` under the hood. The reason we still create such a smartcast expression is for diagnostics
-    // purpose only.
-    override val typeRef: FirTypeRef get() = if (smartcastStability == SmartcastStability.STABLE_VALUE) smartcastType else originalType
 
     override fun <D> transformChildren(transformer: FirTransformer<D>, data: D): FirExpressionWithSmartcast {
         originalExpression = originalExpression.transformSingle(transformer, data)
diff --git a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/impl/FirExpressionWithSmartcastToNullImpl.kt b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/impl/FirExpressionWithSmartcastToNullImpl.kt
index f9fe37f7e30..117b4c8702b 100644
--- a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/impl/FirExpressionWithSmartcastToNullImpl.kt
+++ b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/impl/FirExpressionWithSmartcastToNullImpl.kt
@@ -16,13 +16,11 @@ import org.jetbrains.kotlin.fir.types.FirTypeRef
 import org.jetbrains.kotlin.fir.visitors.FirTransformer
 import org.jetbrains.kotlin.fir.visitors.FirVisitor
 import org.jetbrains.kotlin.fir.visitors.transformSingle
-import org.jetbrains.kotlin.types.SmartcastStability
 
 class FirExpressionWithSmartcastToNullImpl(
     override var originalExpression: FirQualifiedAccessExpression,
-    override val smartcastType: FirTypeRef,
-    override val typesFromSmartCast: Collection<ConeKotlinType>,
-    override val smartcastStability: SmartcastStability
+    override val typeRef: FirTypeRef,
+    override val typesFromSmartCast: Collection<ConeKotlinType>
 ) : FirExpressionWithSmartcastToNull() {
     init {
         assert(originalExpression.typeRef is FirResolvedTypeRef)
@@ -36,10 +34,6 @@ class FirExpressionWithSmartcastToNullImpl(
     override val extensionReceiver: FirExpression get() = originalExpression.extensionReceiver
     override val calleeReference: FirReference get() = originalExpression.calleeReference
     override val originalType: FirTypeRef get() = originalExpression.typeRef
-    // A FirExpressionWithSmartcast is only an effective smartcast if `smartcastStability == SmartcastStability.STABLE_VALUE`. Otherwise,
-    // it's the same as the `originalExpression` under the hood. The reason we still create such a smartcast expression is for diagnostics
-    // purpose only.
-    override val typeRef: FirTypeRef get() = if (smartcastStability == SmartcastStability.STABLE_VALUE) smartcastType else originalType
 
     override fun <D> transformChildren(transformer: FirTransformer<D>, data: D): FirExpressionWithSmartcastToNull {
         originalExpression = originalExpression.transformSingle(transformer, data)
diff --git a/compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/FieldSets.kt b/compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/FieldSets.kt
index 77eae4678df..64f13f0dde8 100644
--- a/compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/FieldSets.kt
+++ b/compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/FieldSets.kt
@@ -83,6 +83,4 @@ object FieldSets {
     val modality = field(modalityType, nullable = true)
 
     val scopeProvider = field("scopeProvider", firScopeProviderType)
-
-    val smartcastStability = field(smartcastStabilityType)
 }
diff --git a/compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/NodeConfigurator.kt b/compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/NodeConfigurator.kt
index 0e1db276ab2..03bf0c8fbd7 100644
--- a/compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/NodeConfigurator.kt
+++ b/compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/NodeConfigurator.kt
@@ -19,7 +19,6 @@ import org.jetbrains.kotlin.fir.tree.generator.FieldSets.name
 import org.jetbrains.kotlin.fir.tree.generator.FieldSets.receivers
 import org.jetbrains.kotlin.fir.tree.generator.FieldSets.returnTypeRef
 import org.jetbrains.kotlin.fir.tree.generator.FieldSets.scopeProvider
-import org.jetbrains.kotlin.fir.tree.generator.FieldSets.smartcastStability
 import org.jetbrains.kotlin.fir.tree.generator.FieldSets.status
 import org.jetbrains.kotlin.fir.tree.generator.FieldSets.superTypeRefs
 import org.jetbrains.kotlin.fir.tree.generator.FieldSets.symbol
@@ -459,8 +458,6 @@ object NodeConfigurator : AbstractFieldConfigurator<FirTreeBuilder>(FirTreeBuild
             +field("originalExpression", qualifiedAccessExpression)
             +field("typesFromSmartCast", "Collection<ConeKotlinType>", null, customType = coneKotlinTypeType)
             +field("originalType", typeRef)
-            +field("smartcastType", typeRef)
-            +smartcastStability
         }
 
         expressionWithSmartcastToNull.configure {
diff --git a/compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/Types.kt b/compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/Types.kt
index 51ae3c6889f..807b29ee159 100644
--- a/compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/Types.kt
+++ b/compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/Types.kt
@@ -17,7 +17,6 @@ import org.jetbrains.kotlin.fir.types.ConeKotlinType
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
-import org.jetbrains.kotlin.types.SmartcastStability
 import org.jetbrains.kotlin.types.Variance
 
 val sourceElementType = type("fir", "FirSourceElement")
@@ -32,7 +31,6 @@ val nameType = type(Name::class)
 val visibilityType = type(Visibility::class)
 val effectiveVisibilityType = type("descriptors", "EffectiveVisibility")
 val modalityType = type(Modality::class)
-val smartcastStabilityType = type(SmartcastStability::class)
 val fqNameType = type(FqName::class)
 val classIdType = type(ClassId::class)
 val annotationUseSiteTargetType = type(AnnotationUseSiteTarget::class)
diff --git a/core/compiler.common/src/org/jetbrains/kotlin/types/SmartcastStability.kt b/core/compiler.common/src/org/jetbrains/kotlin/types/SmartcastStability.kt
deleted file mode 100644
index a7ba64f1806..00000000000
--- a/core/compiler.common/src/org/jetbrains/kotlin/types/SmartcastStability.kt
+++ /dev/null
@@ -1,39 +0,0 @@
-/*
- * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
- * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
- */
-
-package org.jetbrains.kotlin.types
-
-/**
- * See https://kotlinlang.org/spec/type-inference.html#smart-cast-sink-stability for explanation on smartcast stability. The "mutable value
- * capturing" and "concurrent writes" categories in the spec are covered by [CAPTURED_VARIABLE] and [MUTABLE_PROPERTY] together.
- * Specifically, we only do capture analysis on local mutable properties. Non-local ones are considered to be always unstable (assuming
- * some concurrent writes are always present).
- */
-enum class SmartcastStability(private val str: String, val description: String = str) {
-    // Local value, or parameter, or private / internal member value without open / custom getter,
-    // or protected / public member value from the same module without open / custom getter
-    // Smart casts are completely safe
-    STABLE_VALUE("stable val"),
-
-    // Member value with open / custom getter
-    // Smart casts are not safe
-    PROPERTY_WITH_GETTER("custom getter", "property that has open or custom getter"),
-
-    // Protected / public member value from another module
-    // Smart casts are not safe
-    ALIEN_PUBLIC_PROPERTY("alien public", "public API property declared in different module"),
-
-    // Local variable already captured by a changing closure
-    // Smart casts are not safe
-    CAPTURED_VARIABLE("captured var", "local variable that is captured by a changing closure"),
-
-    // Member variable regardless of its visibility
-    // Smart casts are not safe
-    MUTABLE_PROPERTY("member", "mutable property that could have been changed by this time"),
-
-    // A delegated property.
-    // Smart casts are not safe
-    DELEGATED_PROPERTY("delegate", "delegated property that could have been changed by this time"),
-}