diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirEqualityCompatibilityChecker.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirEqualityCompatibilityChecker.kt
index 120096616fa..2c4949004f2 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirEqualityCompatibilityChecker.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirEqualityCompatibilityChecker.kt
@@ -25,7 +25,6 @@ import org.jetbrains.kotlin.fir.expressions.*
 import org.jetbrains.kotlin.fir.isPrimitiveType
 import org.jetbrains.kotlin.fir.resolve.fullyExpandedType
 import org.jetbrains.kotlin.fir.symbols.impl.FirClassSymbol
-import org.jetbrains.kotlin.fir.symbols.impl.FirRegularClassSymbol
 import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.fir.types.impl.ConeClassLikeTypeImpl
 import org.jetbrains.kotlin.name.StandardClassIds
@@ -101,15 +100,11 @@ object FirEqualityCompatibilityChecker : FirEqualityOperatorCallChecker(MppCheck
     }
 
     private fun checkIdentityApplicability(l: TypeInfo, r: TypeInfo, context: CheckerContext): Applicability {
-        // The compiler should only check comparisons
-        // when identity-less types or builtins are involved.
-
-        val oneIsBuiltin = l.isBuiltin || r.isBuiltin
         val oneIsNotNull = !l.type.isNullable || !r.type.isNullable
 
         return when {
             l.isIdentityLess || r.isIdentityLess -> Applicability.INAPPLICABLE_AS_IDENTITY_LESS
-            oneIsBuiltin && oneIsNotNull && shouldReportAsPerRules1(l, r, context) -> getInapplicabilityFor(l, r)
+            oneIsNotNull && shouldReportAsPerRules1(l, r, context) -> getInapplicabilityFor(l, r)
             else -> Applicability.APPLICABLE
         }
     }
@@ -126,13 +121,12 @@ object FirEqualityCompatibilityChecker : FirEqualityOperatorCallChecker(MppCheck
     }
 
     private fun shouldReportAsPerRules1(l: TypeInfo, r: TypeInfo, context: CheckerContext): Boolean {
-        // Builtins are always final classes, so
-        // we only need to check if one is related
-        // to the other
+        val oneIsFinal = l.isFinal || r.isFinal
 
         return when {
             l.type.isNothingOrNullableNothing || r.type.isNothingOrNullableNothing -> false
-            else -> !l.isSubtypeOf(r, context) && !r.isSubtypeOf(l, context)
+            oneIsFinal -> !l.isSubtypeOf(r, context) && !r.isSubtypeOf(l, context)
+            else -> false
         }
     }
 
@@ -302,6 +296,7 @@ private class TypeInfo(
     val isPrimitive: Boolean,
     val isBuiltin: Boolean,
     val isValueClass: Boolean,
+    val isFinal: Boolean,
     val canHaveSubtypesAccordingToK1: Boolean,
 ) {
     override fun toString() = "$type"
@@ -309,20 +304,6 @@ private class TypeInfo(
 
 private val FirClassSymbol<*>.isBuiltin get() = isPrimitiveType() || classId == StandardClassIds.String || isEnumClass
 
-// This property is used to replicate K1 behavior, and it
-// tries to match the `TypeUtils.canHaveSubtypes(typeChecker, type)`
-// check in the K1 intersector.
-// In K2 enum classes are final, though enum entries are their subclasses.
-private fun ConeKotlinType.canHaveSubtypesAccordingToK1(session: FirSession): Boolean {
-    val symbol = toSymbol(session)
-
-    return when {
-        symbol is FirRegularClassSymbol && symbol.isEnumClass -> true
-        symbol is FirClassSymbol<*> && symbol.isFinalClass -> false
-        else -> true
-    }
-}
-
 private val TypeInfo.isNullableEnum get() = isEnumClass && type.isNullable
 
 private val TypeInfo.isIdentityLess get() = isPrimitive || isValueClass
@@ -350,7 +331,9 @@ private fun ConeKotlinType.toTypeInfo(session: FirSession): TypeInfo {
         isPrimitive = bounds.any { it.isPrimitiveOrNullablePrimitive },
         isBuiltin = bounds.any { it.toClassSymbol(session)?.isBuiltin == true },
         isValueClass = bounds.any { it.toClassSymbol(session)?.isInline == true },
-        canHaveSubtypesAccordingToK1(session),
+        isFinal = bounds.any { it.toClassSymbol(session)?.isFinalClass == true },
+        // In K1's intersector, `canHaveSubtypes()` is called for `nullabilityStripped`.
+        withNullability(ConeNullability.NOT_NULL, session.typeContext).canHaveSubtypes(session),
     )
 }
 
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirPrivateToThisAccessChecker.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirPrivateToThisAccessChecker.kt
index 1929335ee98..0d3c331fa99 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirPrivateToThisAccessChecker.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirPrivateToThisAccessChecker.kt
@@ -38,7 +38,8 @@ object FirPrivateToThisAccessChecker : FirQualifiedAccessExpressionChecker(MppCh
             // If there was a visibility diagnostic, no need to report another one about visibility
             when (reference.diagnostic) {
                 is ConeVisibilityError,
-                is ConeSetterVisibilityError -> return
+                is ConeSetterVisibilityError
+                -> return
             }
         }
         val dispatchReceiver = expression.dispatchReceiver ?: return
@@ -147,12 +148,4 @@ object FirPrivateToThisAccessChecker : FirQualifiedAccessExpressionChecker(MppCh
         }
         return false
     }
-
-    private val ConeTypeProjection.variance: Variance
-        get() = when (this.kind) {
-            ProjectionKind.STAR -> Variance.OUT_VARIANCE
-            ProjectionKind.IN -> Variance.IN_VARIANCE
-            ProjectionKind.OUT -> Variance.OUT_VARIANCE
-            ProjectionKind.INVARIANT -> Variance.INVARIANT
-        }
 }
diff --git a/compiler/fir/cones/src/org/jetbrains/kotlin/fir/types/ConeTypeProjection.kt b/compiler/fir/cones/src/org/jetbrains/kotlin/fir/types/ConeTypeProjection.kt
index 0a765a24e5c..ac4e46c7362 100644
--- a/compiler/fir/cones/src/org/jetbrains/kotlin/fir/types/ConeTypeProjection.kt
+++ b/compiler/fir/cones/src/org/jetbrains/kotlin/fir/types/ConeTypeProjection.kt
@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.fir.types
 
+import org.jetbrains.kotlin.types.Variance
 import org.jetbrains.kotlin.types.model.TypeArgumentMarker
 
 enum class ProjectionKind {
@@ -84,3 +85,11 @@ fun ConeKotlinTypeProjection.replaceType(newType: ConeKotlinType): ConeKotlinTyp
         is ConeKotlinTypeConflictingProjection -> ConeKotlinTypeConflictingProjection(newType)
     }
 }
+
+val ConeTypeProjection.variance: Variance
+    get() = when (this.kind) {
+        ProjectionKind.STAR -> Variance.OUT_VARIANCE
+        ProjectionKind.IN -> Variance.IN_VARIANCE
+        ProjectionKind.OUT -> Variance.OUT_VARIANCE
+        ProjectionKind.INVARIANT -> Variance.INVARIANT
+    }
diff --git a/compiler/fir/providers/src/org/jetbrains/kotlin/fir/types/TypeUtils.kt b/compiler/fir/providers/src/org/jetbrains/kotlin/fir/types/TypeUtils.kt
index 1104d3a19fb..6df5ece3d9f 100644
--- a/compiler/fir/providers/src/org/jetbrains/kotlin/fir/types/TypeUtils.kt
+++ b/compiler/fir/providers/src/org/jetbrains/kotlin/fir/types/TypeUtils.kt
@@ -584,12 +584,16 @@ fun FirCallableDeclaration.isSubtypeOf(
     )
 }
 
+/**
+ * The original K1 function: [org.jetbrains.kotlin.types.TypeUtils.canHaveSubtypes].
+ */
 fun ConeKotlinType.canHaveSubtypes(session: FirSession): Boolean {
     if (this.isMarkedNullable) {
         return true
     }
     val expandedType = fullyExpandedType(session)
     val classSymbol = expandedType.toSymbol(session) as? FirRegularClassSymbol ?: return true
+    // In K2 enum classes are final, though enum entries are their subclasses (which is a compiler implementation detail).
     if (classSymbol.isEnumClass || classSymbol.isExpect || classSymbol.modality != Modality.FINAL) {
         return true
     }
@@ -603,49 +607,18 @@ fun ConeKotlinType.canHaveSubtypes(session: FirSession): Boolean {
 
         val argument = typeProjection.type!! //safe because it is not a star
 
-        when (typeParameterSymbol.variance) {
-            Variance.INVARIANT ->
-                when (typeProjection.kind) {
-                    ProjectionKind.INVARIANT ->
-                        if (lowerThanBound(session.typeContext, argument, typeParameterSymbol) || argument.canHaveSubtypes(session)) {
-                            return true
-                        }
+        val canHaveSubtypes = when (typeProjection.variance) {
+            Variance.OUT_VARIANCE -> argument.canHaveSubtypes(session)
+            Variance.IN_VARIANCE -> argument.lowerThanBound(typeParameterSymbol, session)
+            Variance.INVARIANT -> when (typeParameterSymbol.variance) {
+                Variance.OUT_VARIANCE -> argument.canHaveSubtypes(session)
+                Variance.IN_VARIANCE -> argument.lowerThanBound(typeParameterSymbol, session)
+                Variance.INVARIANT -> argument.canHaveSubtypes(session) || argument.lowerThanBound(typeParameterSymbol, session)
+            }
+        }
 
-                    ProjectionKind.IN ->
-                        if (lowerThanBound(session.typeContext, argument, typeParameterSymbol)) {
-                            return true
-                        }
-
-                    ProjectionKind.OUT ->
-                        if (argument.canHaveSubtypes(session)) {
-                            return true
-                        }
-
-                    ProjectionKind.STAR ->
-                        return true
-                }
-
-            Variance.IN_VARIANCE ->
-                if (typeProjection.kind != ProjectionKind.OUT) {
-                    if (lowerThanBound(session.typeContext, argument, typeParameterSymbol)) {
-                        return true
-                    }
-                } else {
-                    if (argument.canHaveSubtypes(session)) {
-                        return true
-                    }
-                }
-
-            Variance.OUT_VARIANCE ->
-                if (typeProjection.kind != ProjectionKind.IN) {
-                    if (argument.canHaveSubtypes(session)) {
-                        return true
-                    }
-                } else {
-                    if (lowerThanBound(session.typeContext, argument, typeParameterSymbol)) {
-                        return true
-                    }
-                }
+        if (canHaveSubtypes) {
+            return true
         }
     }
 
@@ -668,9 +641,14 @@ fun ConeClassLikeType.toClassSymbol(session: FirSession): FirClassSymbol<*>? {
     return fullyExpandedType(session).toSymbol(session) as? FirClassSymbol<*>
 }
 
-private fun lowerThanBound(context: ConeInferenceContext, argument: ConeKotlinType, typeParameterSymbol: FirTypeParameterSymbol): Boolean {
+/**
+ * The original K1 function: [org.jetbrains.kotlin.types.TypeUtils.lowerThanBound].
+ * This function returns `true` if `argument` suits any bound rather than the
+ * intersection of them all, and it expects there to be at least a single bound.
+ */
+private fun ConeKotlinType.lowerThanBound(typeParameterSymbol: FirTypeParameterSymbol, session: FirSession): Boolean {
     typeParameterSymbol.resolvedBounds.forEach { boundTypeRef ->
-        if (argument != boundTypeRef.coneType && argument.isSubtypeOf(context, boundTypeRef.coneType)) {
+        if (this != boundTypeRef.coneType && isSubtypeOf(session.typeContext, boundTypeRef.coneType)) {
             return true
         }
     }
diff --git a/compiler/testData/diagnostics/tests/comparingArbitraryClasses.fir.kt b/compiler/testData/diagnostics/tests/comparingArbitraryClasses.fir.kt
index 3542584195c..3b988f820cf 100644
--- a/compiler/testData/diagnostics/tests/comparingArbitraryClasses.fir.kt
+++ b/compiler/testData/diagnostics/tests/comparingArbitraryClasses.fir.kt
@@ -5,5 +5,5 @@ class A
 class B
 fun main() {
     A() == B()
-    A() === B()
+    <!EQUALITY_NOT_APPLICABLE!>A() === B()<!>
 }
diff --git a/compiler/testData/diagnostics/tests/comparingCallableReferencesWithInstanceOfJavaClass.kt b/compiler/testData/diagnostics/tests/comparingCallableReferencesWithInstanceOfJavaClass.kt
index 20615bedb41..9d06ef2a73c 100644
--- a/compiler/testData/diagnostics/tests/comparingCallableReferencesWithInstanceOfJavaClass.kt
+++ b/compiler/testData/diagnostics/tests/comparingCallableReferencesWithInstanceOfJavaClass.kt
@@ -16,6 +16,9 @@ fun test (j: J, k: K) {
     j == K::f
     j == k::f
 
+    j === K::f
+    j === k::f
+
     when (j) {
         k::f -> ""
         K::f -> ""
diff --git a/compiler/testData/diagnostics/tests/comparisonOfGenericInterfaceWithGenericClass.fir.kt b/compiler/testData/diagnostics/tests/comparisonOfGenericInterfaceWithGenericClass.fir.kt
new file mode 100644
index 00000000000..eae3326b06d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/comparisonOfGenericInterfaceWithGenericClass.fir.kt
@@ -0,0 +1,8 @@
+// ISSUE: KT-47884
+
+interface A<X>
+class B<T>
+
+fun foo(a: A<*>, b: B<*>): Boolean = a == b
+
+fun bar(a: A<*>, b: B<*>): Boolean = <!EQUALITY_NOT_APPLICABLE_WARNING!>a === b<!>
diff --git a/compiler/testData/diagnostics/tests/comparisonOfGenericInterfaceWithGenericClass.kt b/compiler/testData/diagnostics/tests/comparisonOfGenericInterfaceWithGenericClass.kt
index 7261d2be82a..9fc13b851d6 100644
--- a/compiler/testData/diagnostics/tests/comparisonOfGenericInterfaceWithGenericClass.kt
+++ b/compiler/testData/diagnostics/tests/comparisonOfGenericInterfaceWithGenericClass.kt
@@ -1,7 +1,8 @@
-// FIR_IDENTICAL
 // ISSUE: KT-47884
 
 interface A<X>
 class B<T>
 
 fun foo(a: A<*>, b: B<*>): Boolean = a == b
+
+fun bar(a: A<*>, b: B<*>): Boolean = a === b
diff --git a/compiler/testData/diagnostics/tests/differentNumericTypesFromSmartCast.fir.kt b/compiler/testData/diagnostics/tests/differentNumericTypesFromSmartCast.fir.kt
index 57e3286176d..66d048e4794 100644
--- a/compiler/testData/diagnostics/tests/differentNumericTypesFromSmartCast.fir.kt
+++ b/compiler/testData/diagnostics/tests/differentNumericTypesFromSmartCast.fir.kt
@@ -5,3 +5,9 @@ fun test(x: Any, y: Any) =
 
 fun test(x: Float, y: Double) =
     <!EQUALITY_NOT_APPLICABLE!>x == y<!>
+
+fun fest(x: Any, y: Any) =
+    x is Float && y is Double && <!FORBIDDEN_IDENTITY_EQUALS_WARNING!>x === y<!>
+
+fun fest(x: Float, y: Double) =
+    <!FORBIDDEN_IDENTITY_EQUALS!>x === y<!>
diff --git a/compiler/testData/diagnostics/tests/differentNumericTypesFromSmartCast.kt b/compiler/testData/diagnostics/tests/differentNumericTypesFromSmartCast.kt
index 409da498788..cfab12dcbf5 100644
--- a/compiler/testData/diagnostics/tests/differentNumericTypesFromSmartCast.kt
+++ b/compiler/testData/diagnostics/tests/differentNumericTypesFromSmartCast.kt
@@ -5,3 +5,9 @@ fun test(x: Any, y: Any) =
 
 fun test(x: Float, y: Double) =
     <!EQUALITY_NOT_APPLICABLE!>x == y<!>
+
+fun fest(x: Any, y: Any) =
+    x is Float && y is Double && x === y
+
+fun fest(x: Float, y: Double) =
+    <!EQUALITY_NOT_APPLICABLE!>x === y<!>
diff --git a/compiler/testData/diagnostics/tests/enum/compareTwoDifferentEnums.kt b/compiler/testData/diagnostics/tests/enum/compareTwoDifferentEnums.kt
index 049d7c169d2..d6eced2e7ed 100644
--- a/compiler/testData/diagnostics/tests/enum/compareTwoDifferentEnums.kt
+++ b/compiler/testData/diagnostics/tests/enum/compareTwoDifferentEnums.kt
@@ -16,3 +16,7 @@ enum class KotlinEnumB
 fun jj(a: JavaEnumA, b: JavaEnumB) = <!INCOMPATIBLE_ENUM_COMPARISON!>a == b<!>
 fun jk(a: JavaEnumA, b: KotlinEnumB) = <!INCOMPATIBLE_ENUM_COMPARISON!>a == b<!>
 fun kk(a: KotlinEnumA, b: KotlinEnumB) = <!INCOMPATIBLE_ENUM_COMPARISON!>a == b<!>
+
+fun jj2(a: JavaEnumA, b: JavaEnumB) = <!INCOMPATIBLE_ENUM_COMPARISON!>a === b<!>
+fun jk2(a: JavaEnumA, b: KotlinEnumB) = <!INCOMPATIBLE_ENUM_COMPARISON!>a === b<!>
+fun kk2(a: KotlinEnumA, b: KotlinEnumB) = <!INCOMPATIBLE_ENUM_COMPARISON!>a === b<!>
diff --git a/compiler/testData/diagnostics/tests/enum/compareTwoDifferentEnums.txt b/compiler/testData/diagnostics/tests/enum/compareTwoDifferentEnums.txt
index 306501cee79..9ce7ee5813b 100644
--- a/compiler/testData/diagnostics/tests/enum/compareTwoDifferentEnums.txt
+++ b/compiler/testData/diagnostics/tests/enum/compareTwoDifferentEnums.txt
@@ -1,8 +1,11 @@
 package
 
 public fun jj(/*0*/ a: JavaEnumA, /*1*/ b: JavaEnumB): kotlin.Boolean
+public fun jj2(/*0*/ a: JavaEnumA, /*1*/ b: JavaEnumB): kotlin.Boolean
 public fun jk(/*0*/ a: JavaEnumA, /*1*/ b: KotlinEnumB): kotlin.Boolean
+public fun jk2(/*0*/ a: JavaEnumA, /*1*/ b: KotlinEnumB): kotlin.Boolean
 public fun kk(/*0*/ a: KotlinEnumA, /*1*/ b: KotlinEnumB): kotlin.Boolean
+public fun kk2(/*0*/ a: KotlinEnumA, /*1*/ b: KotlinEnumB): kotlin.Boolean
 
 public final enum class JavaEnumA : kotlin.Enum<JavaEnumA!> {
     public constructor JavaEnumA()
diff --git a/compiler/testData/diagnostics/tests/enum/equalityOfEnumAndParameter.fir.kt b/compiler/testData/diagnostics/tests/enum/equalityOfEnumAndParameter.fir.kt
index 1760777bf74..c962352989a 100644
--- a/compiler/testData/diagnostics/tests/enum/equalityOfEnumAndParameter.fir.kt
+++ b/compiler/testData/diagnostics/tests/enum/equalityOfEnumAndParameter.fir.kt
@@ -26,6 +26,11 @@ fun <P> processInfo1(info: String, printer: P) where P: Buffered, P: AIPowered {
     <!INCOMPATIBLE_ENUM_COMPARISON!>printer == BufferedEnum.A<!>
     <!INCOMPATIBLE_ENUM_COMPARISON!>printer == UsualEnum.C<!>
     printer == CleverEnum.E
+
+    <!FORBIDDEN_IDENTITY_EQUALS!>printer === 20<!>
+    <!INCOMPATIBLE_ENUM_COMPARISON!>printer === BufferedEnum.A<!>
+    <!INCOMPATIBLE_ENUM_COMPARISON!>printer === UsualEnum.C<!>
+    printer === CleverEnum.E
 }
 
 fun <P> processInfo2(info: String, printer: P) where P: AIPowered, P: Buffered {
@@ -33,6 +38,11 @@ fun <P> processInfo2(info: String, printer: P) where P: AIPowered, P: Buffered {
     <!INCOMPATIBLE_ENUM_COMPARISON!>printer == BufferedEnum.A<!>
     <!INCOMPATIBLE_ENUM_COMPARISON!>printer == UsualEnum.C<!>
     printer == CleverEnum.E
+
+    <!FORBIDDEN_IDENTITY_EQUALS!>printer === 20<!>
+    <!INCOMPATIBLE_ENUM_COMPARISON!>printer === BufferedEnum.A<!>
+    <!INCOMPATIBLE_ENUM_COMPARISON!>printer === UsualEnum.C<!>
+    printer === CleverEnum.E
 }
 
 abstract class Printer {
@@ -44,6 +54,11 @@ fun <P> processInfo3(info: String, printer: P) where P: Buffered, P: Printer {
     <!INCOMPATIBLE_ENUM_COMPARISON!>printer == BufferedEnum.A<!>
     <!INCOMPATIBLE_ENUM_COMPARISON!>printer == UsualEnum.C<!>
     <!INCOMPATIBLE_ENUM_COMPARISON!>printer == CleverEnum.E<!>
+
+    <!FORBIDDEN_IDENTITY_EQUALS!>printer === 20<!>
+    <!INCOMPATIBLE_ENUM_COMPARISON!>printer === BufferedEnum.A<!>
+    <!INCOMPATIBLE_ENUM_COMPARISON!>printer === UsualEnum.C<!>
+    <!INCOMPATIBLE_ENUM_COMPARISON!>printer === CleverEnum.E<!>
 }
 
 fun test(a: Int, b: Any?) {
diff --git a/compiler/testData/diagnostics/tests/enum/equalityOfEnumAndParameter.kt b/compiler/testData/diagnostics/tests/enum/equalityOfEnumAndParameter.kt
index c0ac3ad09aa..420f3f4391d 100644
--- a/compiler/testData/diagnostics/tests/enum/equalityOfEnumAndParameter.kt
+++ b/compiler/testData/diagnostics/tests/enum/equalityOfEnumAndParameter.kt
@@ -26,6 +26,11 @@ fun <P> processInfo1(info: String, printer: P) where P: Buffered, P: AIPowered {
     printer == BufferedEnum.A
     <!INCOMPATIBLE_ENUM_COMPARISON_ERROR!>printer == UsualEnum.C<!>
     printer == CleverEnum.E
+
+    <!EQUALITY_NOT_APPLICABLE!>printer === 20<!>
+    printer === BufferedEnum.A
+    <!INCOMPATIBLE_ENUM_COMPARISON_ERROR!>printer === UsualEnum.C<!>
+    printer === CleverEnum.E
 }
 
 fun <P> processInfo2(info: String, printer: P) where P: AIPowered, P: Buffered {
@@ -33,6 +38,11 @@ fun <P> processInfo2(info: String, printer: P) where P: AIPowered, P: Buffered {
     <!INCOMPATIBLE_ENUM_COMPARISON_ERROR!>printer == BufferedEnum.A<!>
     <!INCOMPATIBLE_ENUM_COMPARISON_ERROR!>printer == UsualEnum.C<!>
     printer == CleverEnum.E
+
+    <!EQUALITY_NOT_APPLICABLE!>printer === 20<!>
+    <!INCOMPATIBLE_ENUM_COMPARISON_ERROR!>printer === BufferedEnum.A<!>
+    <!INCOMPATIBLE_ENUM_COMPARISON_ERROR!>printer === UsualEnum.C<!>
+    printer === CleverEnum.E
 }
 
 abstract class Printer {
@@ -44,6 +54,11 @@ fun <P> processInfo3(info: String, printer: P) where P: Buffered, P: Printer {
     <!INCOMPATIBLE_ENUM_COMPARISON_ERROR!>printer == BufferedEnum.A<!>
     <!INCOMPATIBLE_ENUM_COMPARISON_ERROR!>printer == UsualEnum.C<!>
     <!INCOMPATIBLE_ENUM_COMPARISON_ERROR!>printer == CleverEnum.E<!>
+
+    <!EQUALITY_NOT_APPLICABLE!>printer === 20<!>
+    <!INCOMPATIBLE_ENUM_COMPARISON_ERROR!>printer === BufferedEnum.A<!>
+    <!INCOMPATIBLE_ENUM_COMPARISON_ERROR!>printer === UsualEnum.C<!>
+    <!INCOMPATIBLE_ENUM_COMPARISON_ERROR!>printer === CleverEnum.E<!>
 }
 
 fun test(a: Int, b: Any?) {
diff --git a/compiler/testData/diagnostics/tests/enum/incompatibleEnumEntryClasses.fir.kt b/compiler/testData/diagnostics/tests/enum/incompatibleEnumEntryClasses.fir.kt
new file mode 100644
index 00000000000..b9a289accf0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/incompatibleEnumEntryClasses.fir.kt
@@ -0,0 +1,92 @@
+// !LANGUAGE: -ProhibitComparisonOfIncompatibleEnums
+
+interface I {
+    fun foo()
+}
+
+enum class E1 : I {
+    A {
+        override fun foo() {
+            <!INCOMPATIBLE_ENUM_COMPARISON!>this == E2.A<!>
+
+            val q = this
+            when (q) {
+                this -> {}
+                E1.A -> {}
+                E1.B -> {}
+                <!INCOMPATIBLE_ENUM_COMPARISON!>E2.A<!> -> {}
+                <!INCOMPATIBLE_ENUM_COMPARISON!>E2.B<!> -> {}
+                else -> {}
+            }
+        }
+    },
+    B {
+        override fun foo() {
+
+        }
+    }
+}
+
+enum class E2 : I {
+    A {
+        override fun foo() {
+
+        }
+    },
+    B {
+        override fun foo() {
+
+        }
+    }
+}
+
+fun foo1(e1: E1, e2: E2) {
+    <!INCOMPATIBLE_ENUM_COMPARISON!>e1 == e2<!>
+    <!INCOMPATIBLE_ENUM_COMPARISON!>e1 != e2<!>
+
+    <!INCOMPATIBLE_ENUM_COMPARISON!>e1 == E2.A<!>
+    <!INCOMPATIBLE_ENUM_COMPARISON!>E1.B == e2<!>
+
+    <!INCOMPATIBLE_ENUM_COMPARISON!>E1.A == E2.B<!>
+
+    e1 == E1.A
+    E1.A == e1
+    e2 == E2.B
+    E2.B == e2
+}
+
+fun foo2(e1: E1, e2: E2) {
+    when (e1) {
+        E1.A -> {}
+        <!INCOMPATIBLE_ENUM_COMPARISON!>E2.A<!> -> {}
+        <!INCOMPATIBLE_ENUM_COMPARISON!>E2.B<!> -> {}
+        e1 -> {}
+        <!INCOMPATIBLE_ENUM_COMPARISON!>e2<!> -> {}
+        else -> {}
+    }
+}
+
+fun foo3(e1: Enum<E1>, e2: Enum<E2>, e: Enum<*>) {
+    e1 == e
+    e1 == e2
+
+    e1 == E1.A
+    e1 == E2.A
+
+    when (e1) {
+        e1 -> {}
+        e2 -> {}
+        e -> {}
+        E1.A -> {}
+        E2.A -> {}
+        else -> {}
+    }
+
+    when (e) {
+        e -> {}
+        e2 -> {}
+        E1.A -> {}
+        E2.A -> {}
+        else -> {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/enum/incompatibleEnumEntryClasses.kt b/compiler/testData/diagnostics/tests/enum/incompatibleEnumEntryClasses.kt
index 142407b797a..d206c690a01 100644
--- a/compiler/testData/diagnostics/tests/enum/incompatibleEnumEntryClasses.kt
+++ b/compiler/testData/diagnostics/tests/enum/incompatibleEnumEntryClasses.kt
@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 // !LANGUAGE: -ProhibitComparisonOfIncompatibleEnums
 
 interface I {
diff --git a/compiler/testData/diagnostics/testsWithStdLib/comparingDifferentSubclassesCommonInterface.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/comparingDifferentSubclassesCommonInterface.fir.kt
index 77ad8ad0502..76878757e95 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/comparingDifferentSubclassesCommonInterface.fir.kt
+++ b/compiler/testData/diagnostics/testsWithStdLib/comparingDifferentSubclassesCommonInterface.fir.kt
@@ -7,4 +7,7 @@ class B : I
 fun test(a: A, b: B) {
     a == b
     a == b as I
+
+    <!EQUALITY_NOT_APPLICABLE!>a === b<!>
+    a === b as I
 }
diff --git a/compiler/testData/diagnostics/testsWithStdLib/comparingDifferentSubclassesCommonInterface.kt b/compiler/testData/diagnostics/testsWithStdLib/comparingDifferentSubclassesCommonInterface.kt
index abcba613970..1eb51c77320 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/comparingDifferentSubclassesCommonInterface.kt
+++ b/compiler/testData/diagnostics/testsWithStdLib/comparingDifferentSubclassesCommonInterface.kt
@@ -7,4 +7,7 @@ class B : I
 fun test(a: A, b: B) {
     <!EQUALITY_NOT_APPLICABLE!>a == b<!>
     a == b as I
+
+    <!EQUALITY_NOT_APPLICABLE!>a === b<!>
+    a === b as I
 }
diff --git a/compiler/testData/diagnostics/testsWithStdLib/comparingPlatformTypes.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/comparingPlatformTypes.fir.kt
index 2baf7b005e2..ac456ece8b5 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/comparingPlatformTypes.fir.kt
+++ b/compiler/testData/diagnostics/testsWithStdLib/comparingPlatformTypes.fir.kt
@@ -11,4 +11,7 @@ class A
 fun main(args: Array<String>) {
     (1 to A()) == A()
     (1 to B()) == B()
+
+    <!EQUALITY_NOT_APPLICABLE!>(1 to A()) === A()<!>
+    <!EQUALITY_NOT_APPLICABLE!>(1 to B()) === B()<!>
 }
diff --git a/compiler/testData/diagnostics/testsWithStdLib/comparingPlatformTypes.kt b/compiler/testData/diagnostics/testsWithStdLib/comparingPlatformTypes.kt
index f8fb90e7df7..b64cf2bd1d0 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/comparingPlatformTypes.kt
+++ b/compiler/testData/diagnostics/testsWithStdLib/comparingPlatformTypes.kt
@@ -11,4 +11,7 @@ class A
 fun main(args: Array<String>) {
     <!EQUALITY_NOT_APPLICABLE!>(1 to A()) == A()<!>
     <!EQUALITY_NOT_APPLICABLE!>(1 to B()) == B()<!>
+
+    <!EQUALITY_NOT_APPLICABLE!>(1 to A()) === A()<!>
+    <!EQUALITY_NOT_APPLICABLE!>(1 to B()) === B()<!>
 }
diff --git a/compiler/testData/diagnostics/testsWithStdLib/comparingTripleWithPair.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/comparingTripleWithPair.fir.kt
index 2ef82db994e..6ac3d790fda 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/comparingTripleWithPair.fir.kt
+++ b/compiler/testData/diagnostics/testsWithStdLib/comparingTripleWithPair.fir.kt
@@ -7,4 +7,9 @@ fun test() {
     if (Triple(0, 1, 2) == Pair(Foo.A, "a")) println("Doesn't compile")
     if (Triple(0, 1, 2) == Pair("a", "b")) println("Doesn't compile")
     if (Triple(Foo.A, 1, 2) == Pair(Foo.A, "a")) println("Compiles, but why?")
+
+    <!EQUALITY_NOT_APPLICABLE!>Triple(Foo.A, 1, 2) === Pair("a", "b")<!>
+    <!EQUALITY_NOT_APPLICABLE!>Triple(0, 1, 2) === Pair(Foo.A, "a")<!>
+    <!EQUALITY_NOT_APPLICABLE!>Triple(0, 1, 2) === Pair("a", "b")<!>
+    <!EQUALITY_NOT_APPLICABLE_WARNING!>Triple(Foo.A, 1, 2) === Pair(Foo.A, "a")<!>
 }
diff --git a/compiler/testData/diagnostics/testsWithStdLib/comparingTripleWithPair.kt b/compiler/testData/diagnostics/testsWithStdLib/comparingTripleWithPair.kt
index cfb6b7cb36e..9ce7dae54ff 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/comparingTripleWithPair.kt
+++ b/compiler/testData/diagnostics/testsWithStdLib/comparingTripleWithPair.kt
@@ -7,4 +7,9 @@ fun test() {
     if (<!EQUALITY_NOT_APPLICABLE!>Triple(0, 1, 2) == Pair(Foo.A, "a")<!>) println("Doesn't compile")
     if (<!EQUALITY_NOT_APPLICABLE!>Triple(0, 1, 2) == Pair("a", "b")<!>) println("Doesn't compile")
     if (Triple(Foo.A, 1, 2) == Pair(Foo.A, "a")) println("Compiles, but why?")
+
+    <!EQUALITY_NOT_APPLICABLE!>Triple(Foo.A, 1, 2) === Pair("a", "b")<!>
+    <!EQUALITY_NOT_APPLICABLE!>Triple(0, 1, 2) === Pair(Foo.A, "a")<!>
+    <!EQUALITY_NOT_APPLICABLE!>Triple(0, 1, 2) === Pair("a", "b")<!>
+    Triple(Foo.A, 1, 2) === Pair(Foo.A, "a")
 }
diff --git a/compiler/tests-spec/testData/diagnostics/notLinked/dfa/pos/6.fir.kt b/compiler/tests-spec/testData/diagnostics/notLinked/dfa/pos/6.fir.kt
index 2b290de297e..deb9d33e453 100644
--- a/compiler/tests-spec/testData/diagnostics/notLinked/dfa/pos/6.fir.kt
+++ b/compiler/tests-spec/testData/diagnostics/notLinked/dfa/pos/6.fir.kt
@@ -585,7 +585,7 @@ fun case_29(x: Boolean) {
     if (false || false || false || false || y !== v) {
         val t = <!DEBUG_INFO_EXPRESSION_TYPE("<anonymous>?")!><!UNSAFE_IMPLICIT_INVOKE_CALL!>y<!>()<!>
 
-        if (z !== t || false) {
+        if (<!EQUALITY_NOT_APPLICABLE_WARNING!>z !== t<!> || false) {
             <!DEBUG_INFO_EXPRESSION_TYPE("<anonymous>?")!>t<!><!UNSAFE_CALL!>.<!>a
             <!DEBUG_INFO_EXPRESSION_TYPE("<anonymous>?")!>t<!><!UNSAFE_CALL!>.<!>equals(null)
             <!DEBUG_INFO_EXPRESSION_TYPE("<anonymous>?")!>t<!>.propT