[cls] write contracts information to cls stubs

^ KTIJ-24665
this information would be used to create resolved FirElements from stubs,
so no ProtoBuf would be kept in memory

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/contracts/firContractUtils.kt

@@ -12,10 +12,13 @@ import org.jetbrains.kotlin.analysis.api.contracts.description.booleans.*
 import org.jetbrains.kotlin.analysis.api.fir.KtSymbolByFirBuilder
 import org.jetbrains.kotlin.analysis.api.fir.symbols.KtFirFunctionSymbol
 import org.jetbrains.kotlin.analysis.api.symbols.KtParameterSymbol
+import org.jetbrains.kotlin.contracts.description.*
 import org.jetbrains.kotlin.fir.contracts.description.*
-import org.jetbrains.kotlin.fir.expressions.LogicOperationKind
+import org.jetbrains.kotlin.fir.diagnostics.ConeDiagnostic
+import org.jetbrains.kotlin.contracts.description.LogicOperationKind
+import org.jetbrains.kotlin.fir.types.ConeKotlinType
 
-internal fun ConeEffectDeclaration.coneEffectDeclarationToAnalysisApi(
+internal fun KtEffectDeclaration<ConeKotlinType, ConeDiagnostic>.coneEffectDeclarationToAnalysisApi(
     builder: KtSymbolByFirBuilder,
     firFunctionSymbol: KtFirFunctionSymbol
 ): KtContractEffectDeclaration =
@@ -24,7 +27,7 @@ internal fun ConeEffectDeclaration.coneEffectDeclarationToAnalysisApi(
 private class ConeContractDescriptionElementToAnalysisApi(
     private val builder: KtSymbolByFirBuilder,
     private val firFunctionSymbol: KtFirFunctionSymbol
-) : ConeContractDescriptionVisitor<Any, Unit>() {
+) : KtContractDescriptionVisitor<Any, Unit, ConeKotlinType, ConeDiagnostic>() {
 
     override fun visitConditionalEffectDeclaration(
         conditionalEffect: ConeConditionalEffectDeclaration,
@@ -39,15 +42,15 @@ private class ConeContractDescriptionElementToAnalysisApi(
         data: Unit
     ): KtContractReturnsContractEffectDeclaration =
         when (val value = returnsEffect.value) {
-            ConeConstantReference.NULL ->
+            ConeContractConstantValues.NULL ->
                 KtContractReturnsSpecificValueEffectDeclaration(KtContractConstantValue(KtContractConstantType.NULL, builder.token))
-            ConeConstantReference.NOT_NULL -> KtContractReturnsNotNullEffectDeclaration(builder.token)
-            ConeConstantReference.WILDCARD -> KtContractReturnsSuccessfullyEffectDeclaration(builder.token)
-            is ConeBooleanConstantReference -> KtContractReturnsSpecificValueEffectDeclaration(
+            ConeContractConstantValues.NOT_NULL -> KtContractReturnsNotNullEffectDeclaration(builder.token)
+            ConeContractConstantValues.WILDCARD -> KtContractReturnsSuccessfullyEffectDeclaration(builder.token)
+            is KtBooleanConstantReference -> KtContractReturnsSpecificValueEffectDeclaration(
                 KtContractConstantValue(
                     when (value) {
-                        ConeBooleanConstantReference.TRUE -> KtContractConstantType.TRUE
-                        ConeBooleanConstantReference.FALSE -> KtContractConstantType.FALSE
+                        ConeContractConstantValues.TRUE -> KtContractConstantType.TRUE
+                        ConeContractConstantValues.FALSE -> KtContractConstantType.FALSE
                         else -> error("Can't convert $value to the Analysis API")
                     },
                     builder.token
@@ -56,7 +59,7 @@ private class ConeContractDescriptionElementToAnalysisApi(
             else -> error("Can't convert $returnsEffect to the Analysis API")
         }
 
-    override fun visitCallsEffectDeclaration(callsEffect: ConeCallsEffectDeclaration, data: Unit): KtContractCallsInPlaceContractEffectDeclaration =
+    override fun visitCallsEffectDeclaration(callsEffect: KtCallsEffectDeclaration<ConeKotlinType, ConeDiagnostic>, data: Unit): KtContractCallsInPlaceContractEffectDeclaration =
         KtContractCallsInPlaceContractEffectDeclaration(
             callsEffect.valueParameterReference.accept(),
             callsEffect.kind
@@ -92,8 +95,8 @@ private class ConeContractDescriptionElementToAnalysisApi(
         data: Unit
     ): KtContractBooleanConstantExpression =
         when (booleanConstantDescriptor) {
-            ConeBooleanConstantReference.TRUE -> KtContractBooleanConstantExpression(true, builder.token)
-            ConeBooleanConstantReference.FALSE -> KtContractBooleanConstantExpression(false, builder.token)
+            ConeContractConstantValues.TRUE -> KtContractBooleanConstantExpression(true, builder.token)
+            ConeContractConstantValues.FALSE -> KtContractBooleanConstantExpression(false, builder.token)
             else -> error("Can't convert $booleanConstantDescriptor to Analysis API")
         }
 

analysis/decompiled/decompiler-to-file-stubs/testData/additionalClsStubInfo/Contracts/Contracts.kt

@@ -0,0 +1,77 @@
+// JVM_FILE_NAME: ContractsKt
+
+@file:OptIn(ExperimentalContracts::class)
+package test
+
+import kotlin.contracts.*
+
+fun myRequire(x: Boolean) {
+    contract {
+        returns() implies x
+    }
+}
+
+fun <R> call_InPlace(block: () -> R): R {
+    contract {
+        callsInPlace(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+fun isNull(obj: Any?): Boolean {
+    contract {
+        returns(true) implies (obj != null)
+    }
+    return obj != null
+}
+
+fun isNotNull(foo: Any?): Any? {
+    contract {
+        returnsNotNull() implies (foo != null)
+    }
+    return foo
+}
+
+fun isString(foo: Any?): String? {
+    contract {
+        returnsNotNull() implies (foo is String)
+    }
+    return foo as? String
+}
+
+fun isNotString(foo: Any?): String? {
+    contract {
+        returnsNotNull() implies (foo !is String)
+    }
+    return if (foo is String) null else "not a string"
+}
+
+fun String?.asSafe(): String? {
+    contract {
+        returnsNotNull() implies (this@asSafe != null)
+    }
+    return this
+}
+
+fun isStringCheck(x: Any?): Any? {
+    contract {
+        returns(true) implies (x is Comparable<*> || x is CharSequence)
+    }
+
+    return x is String
+}
+
+fun isStringOrNumber(x: Any?): Any? {
+    contract {
+        returns(true) implies (x is Comparable<*> && (x is CharSequence || x is Number))
+    }
+
+    return x is String || x is Int
+}
+
+inline fun <reified T : Number> T?.test0(): Boolean {
+    contract {
+        returns(true) implies (this@test0 is T)
+    }
+    return this is T
+}

analysis/decompiled/decompiler-to-file-stubs/testData/additionalClsStubInfo/Contracts/Contracts.txt

@@ -0,0 +1,173 @@
+PsiJetFileStubImpl[package=test]
+KotlinStub$PACKAGE_DIRECTIVE
+  KotlinStub$REFERENCE_EXPRESSION[referencedName=test]
+KotlinStub$IMPORT_LIST
+KotlinStub$FUN[fqName=test.call_InPlace, hasBlockBody=true, hasBody=true, hasTypeParameterListBeforeFunctionName=true, isExtension=false, isTopLevel=true, mayHaveContract=true, name=call_InPlace]
+  effect:CallsInPlace(param(0), EXACTLY_ONCE)
+  KotlinStub$MODIFIER_LIST[public]
+  KotlinStub$TYPE_PARAMETER_LIST
+    KotlinStub$TYPE_PARAMETER[fqName=null, isInVariance=false, isOutVariance=false, name=R]
+  KotlinStub$VALUE_PARAMETER_LIST
+    KotlinStub$VALUE_PARAMETER[fqName=null, hasDefaultValue=false, hasValOrVar=false, isMutable=false, name=block]
+      KotlinStub$TYPE_REFERENCE
+        KotlinStub$FUNCTION_TYPE
+          KotlinStub$VALUE_PARAMETER_LIST
+          KotlinStub$TYPE_REFERENCE
+            KotlinStub$USER_TYPE
+              KotlinStub$REFERENCE_EXPRESSION[referencedName=R]
+  KotlinStub$TYPE_REFERENCE
+    KotlinStub$USER_TYPE
+      KotlinStub$REFERENCE_EXPRESSION[referencedName=R]
+KotlinStub$FUN[fqName=test.isNotNull, hasBlockBody=true, hasBody=true, hasTypeParameterListBeforeFunctionName=false, isExtension=false, isTopLevel=true, mayHaveContract=true, name=isNotNull]
+  effect:Returns(NOT_NULL) -> param(0) != null
+  KotlinStub$MODIFIER_LIST[public]
+  KotlinStub$VALUE_PARAMETER_LIST
+    KotlinStub$VALUE_PARAMETER[fqName=null, hasDefaultValue=false, hasValOrVar=false, isMutable=false, name=foo]
+      KotlinStub$TYPE_REFERENCE
+        KotlinStub$NULLABLE_TYPE
+          KotlinStub$USER_TYPE
+            KotlinStub$USER_TYPE
+              KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=Any]
+  KotlinStub$TYPE_REFERENCE
+    KotlinStub$NULLABLE_TYPE
+      KotlinStub$USER_TYPE
+        KotlinStub$USER_TYPE
+          KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+        KotlinStub$REFERENCE_EXPRESSION[referencedName=Any]
+KotlinStub$FUN[fqName=test.isNotString, hasBlockBody=true, hasBody=true, hasTypeParameterListBeforeFunctionName=false, isExtension=false, isTopLevel=true, mayHaveContract=true, name=isNotString]
+  effect:Returns(NOT_NULL) -> param(0) !is KotlinClassTypeBean(classId=kotlin/String, arguments=[], nullable=false)
+  KotlinStub$MODIFIER_LIST[public]
+  KotlinStub$VALUE_PARAMETER_LIST
+    KotlinStub$VALUE_PARAMETER[fqName=null, hasDefaultValue=false, hasValOrVar=false, isMutable=false, name=foo]
+      KotlinStub$TYPE_REFERENCE
+        KotlinStub$NULLABLE_TYPE
+          KotlinStub$USER_TYPE
+            KotlinStub$USER_TYPE
+              KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=Any]
+  KotlinStub$TYPE_REFERENCE
+    KotlinStub$NULLABLE_TYPE
+      KotlinStub$USER_TYPE
+        KotlinStub$USER_TYPE
+          KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+        KotlinStub$REFERENCE_EXPRESSION[referencedName=String]
+KotlinStub$FUN[fqName=test.isNull, hasBlockBody=true, hasBody=true, hasTypeParameterListBeforeFunctionName=false, isExtension=false, isTopLevel=true, mayHaveContract=true, name=isNull]
+  effect:Returns(TRUE) -> param(0) != null
+  KotlinStub$MODIFIER_LIST[public]
+  KotlinStub$VALUE_PARAMETER_LIST
+    KotlinStub$VALUE_PARAMETER[fqName=null, hasDefaultValue=false, hasValOrVar=false, isMutable=false, name=obj]
+      KotlinStub$TYPE_REFERENCE
+        KotlinStub$NULLABLE_TYPE
+          KotlinStub$USER_TYPE
+            KotlinStub$USER_TYPE
+              KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=Any]
+  KotlinStub$TYPE_REFERENCE
+    KotlinStub$USER_TYPE
+      KotlinStub$USER_TYPE
+        KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+      KotlinStub$REFERENCE_EXPRESSION[referencedName=Boolean]
+KotlinStub$FUN[fqName=test.isString, hasBlockBody=true, hasBody=true, hasTypeParameterListBeforeFunctionName=false, isExtension=false, isTopLevel=true, mayHaveContract=true, name=isString]
+  effect:Returns(NOT_NULL) -> param(0) is KotlinClassTypeBean(classId=kotlin/String, arguments=[], nullable=false)
+  KotlinStub$MODIFIER_LIST[public]
+  KotlinStub$VALUE_PARAMETER_LIST
+    KotlinStub$VALUE_PARAMETER[fqName=null, hasDefaultValue=false, hasValOrVar=false, isMutable=false, name=foo]
+      KotlinStub$TYPE_REFERENCE
+        KotlinStub$NULLABLE_TYPE
+          KotlinStub$USER_TYPE
+            KotlinStub$USER_TYPE
+              KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=Any]
+  KotlinStub$TYPE_REFERENCE
+    KotlinStub$NULLABLE_TYPE
+      KotlinStub$USER_TYPE
+        KotlinStub$USER_TYPE
+          KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+        KotlinStub$REFERENCE_EXPRESSION[referencedName=String]
+KotlinStub$FUN[fqName=test.isStringCheck, hasBlockBody=true, hasBody=true, hasTypeParameterListBeforeFunctionName=false, isExtension=false, isTopLevel=true, mayHaveContract=true, name=isStringCheck]
+  effect:Returns(TRUE) -> param(0) is KotlinClassTypeBean(classId=kotlin/Comparable, arguments=[KotlinTypeArgumentBean(projectionKind=STAR, type=null)], nullable=false) || param(0) is KotlinClassTypeBean(classId=kotlin/CharSequence, arguments=[], nullable=false)
+  KotlinStub$MODIFIER_LIST[public]
+  KotlinStub$VALUE_PARAMETER_LIST
+    KotlinStub$VALUE_PARAMETER[fqName=null, hasDefaultValue=false, hasValOrVar=false, isMutable=false, name=x]
+      KotlinStub$TYPE_REFERENCE
+        KotlinStub$NULLABLE_TYPE
+          KotlinStub$USER_TYPE
+            KotlinStub$USER_TYPE
+              KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=Any]
+  KotlinStub$TYPE_REFERENCE
+    KotlinStub$NULLABLE_TYPE
+      KotlinStub$USER_TYPE
+        KotlinStub$USER_TYPE
+          KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+        KotlinStub$REFERENCE_EXPRESSION[referencedName=Any]
+KotlinStub$FUN[fqName=test.isStringOrNumber, hasBlockBody=true, hasBody=true, hasTypeParameterListBeforeFunctionName=false, isExtension=false, isTopLevel=true, mayHaveContract=true, name=isStringOrNumber]
+  effect:Returns(TRUE) -> param(0) is KotlinClassTypeBean(classId=kotlin/Comparable, arguments=[KotlinTypeArgumentBean(projectionKind=STAR, type=null)], nullable=false) && param(0) is KotlinClassTypeBean(classId=kotlin/CharSequence, arguments=[], nullable=false) || param(0) is KotlinClassTypeBean(classId=kotlin/Number, arguments=[], nullable=false)
+  KotlinStub$MODIFIER_LIST[public]
+  KotlinStub$VALUE_PARAMETER_LIST
+    KotlinStub$VALUE_PARAMETER[fqName=null, hasDefaultValue=false, hasValOrVar=false, isMutable=false, name=x]
+      KotlinStub$TYPE_REFERENCE
+        KotlinStub$NULLABLE_TYPE
+          KotlinStub$USER_TYPE
+            KotlinStub$USER_TYPE
+              KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=Any]
+  KotlinStub$TYPE_REFERENCE
+    KotlinStub$NULLABLE_TYPE
+      KotlinStub$USER_TYPE
+        KotlinStub$USER_TYPE
+          KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+        KotlinStub$REFERENCE_EXPRESSION[referencedName=Any]
+KotlinStub$FUN[fqName=test.myRequire, hasBlockBody=true, hasBody=true, hasTypeParameterListBeforeFunctionName=false, isExtension=false, isTopLevel=true, mayHaveContract=true, name=myRequire]
+  effect:Returns(WILDCARD) -> param(0)
+  KotlinStub$MODIFIER_LIST[public]
+  KotlinStub$VALUE_PARAMETER_LIST
+    KotlinStub$VALUE_PARAMETER[fqName=null, hasDefaultValue=false, hasValOrVar=false, isMutable=false, name=x]
+      KotlinStub$TYPE_REFERENCE
+        KotlinStub$USER_TYPE
+          KotlinStub$USER_TYPE
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+          KotlinStub$REFERENCE_EXPRESSION[referencedName=Boolean]
+  KotlinStub$TYPE_REFERENCE
+    KotlinStub$USER_TYPE
+      KotlinStub$USER_TYPE
+        KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+      KotlinStub$REFERENCE_EXPRESSION[referencedName=Unit]
+KotlinStub$FUN[fqName=test.asSafe, hasBlockBody=true, hasBody=true, hasTypeParameterListBeforeFunctionName=false, isExtension=true, isTopLevel=true, mayHaveContract=true, name=asSafe]
+  effect:Returns(NOT_NULL) -> param(-1) != null
+  KotlinStub$MODIFIER_LIST[public]
+  KotlinStub$TYPE_REFERENCE
+    KotlinStub$NULLABLE_TYPE
+      KotlinStub$USER_TYPE
+        KotlinStub$USER_TYPE
+          KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+        KotlinStub$REFERENCE_EXPRESSION[referencedName=String]
+  KotlinStub$VALUE_PARAMETER_LIST
+  KotlinStub$TYPE_REFERENCE
+    KotlinStub$NULLABLE_TYPE
+      KotlinStub$USER_TYPE
+        KotlinStub$USER_TYPE
+          KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+        KotlinStub$REFERENCE_EXPRESSION[referencedName=String]
+KotlinStub$FUN[fqName=test.test0, hasBlockBody=true, hasBody=true, hasTypeParameterListBeforeFunctionName=true, isExtension=true, isTopLevel=true, mayHaveContract=true, name=test0]
+  effect:Returns(TRUE) -> param(-1) is KotlinTypeParameterTypeBean(typeParameterName=T, nullable=false, definitelyNotNull=false)
+  KotlinStub$MODIFIER_LIST[public inline]
+  KotlinStub$TYPE_PARAMETER_LIST
+    KotlinStub$TYPE_PARAMETER[fqName=null, isInVariance=false, isOutVariance=false, name=T]
+      KotlinStub$MODIFIER_LIST[reified]
+      KotlinStub$TYPE_REFERENCE
+        KotlinStub$USER_TYPE
+          KotlinStub$USER_TYPE
+            KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+          KotlinStub$REFERENCE_EXPRESSION[referencedName=Number]
+  KotlinStub$TYPE_REFERENCE
+    KotlinStub$NULLABLE_TYPE
+      KotlinStub$USER_TYPE
+        KotlinStub$REFERENCE_EXPRESSION[referencedName=T]
+  KotlinStub$VALUE_PARAMETER_LIST
+  KotlinStub$TYPE_REFERENCE
+    KotlinStub$USER_TYPE
+      KotlinStub$USER_TYPE
+        KotlinStub$REFERENCE_EXPRESSION[referencedName=kotlin]
+      KotlinStub$REFERENCE_EXPRESSION[referencedName=Boolean]

analysis/decompiled/decompiler-to-file-stubs/tests/org/jetbrains/kotlin/analysis/decompiler/stub/files/AbstractAdditionalStubInfoTest.kt

@@ -8,6 +8,7 @@ package org.jetbrains.kotlin.analysis.decompiler.stub.files
 import com.intellij.psi.stubs.StubElement
 import com.intellij.util.indexing.FileContentImpl
 import org.jetbrains.kotlin.analysis.decompiler.stub.file.KotlinClsStubBuilder
+import org.jetbrains.kotlin.contracts.description.*
 import org.jetbrains.kotlin.psi.KtProjectionKind
 import org.jetbrains.kotlin.psi.stubs.impl.*
 import org.jetbrains.kotlin.test.KotlinTestUtils
@@ -25,11 +26,22 @@ abstract class AbstractAdditionalStubInfoTest : AbstractDecompiledClassTest() {
 
     private fun extractAdditionInfo(stub: StubElement<*>, builder: StringBuilder, level: Int) {
         builder.append(stub.toString())
-        if (stub is KotlinUserTypeStubImpl) {
-            val upperBound = stub.upperBound
-            if (upperBound != null) {
-                builder.append("    ft: ")
-                appendFlexibleTypeInfo(builder, upperBound)
+        when (stub) {
+            is KotlinUserTypeStubImpl -> {
+                val upperBound = stub.upperBound
+                if (upperBound != null) {
+                    builder.append("    ft: ")
+                    appendFlexibleTypeInfo(builder, upperBound)
+                }
+            }
+            is KotlinFunctionStubImpl -> {
+                val contract = stub.contract
+                if (contract != null) {
+                    for (element in contract) {
+                        builder.append("\n" + "  ".repeat(level)).append("effect:")
+                        element.accept(KotlinContractRenderer(builder), null)
+                    }
+                }
             }
         }
         for (child in stub.childrenStubs) {
@@ -77,4 +89,53 @@ abstract class AbstractAdditionalStubInfoTest : AbstractDecompiledClassTest() {
             }
         }
     }
+}
+
+class KotlinContractRenderer(private val buffer: StringBuilder) : KtContractDescriptionVisitor<Unit, Nothing?, KotlinTypeBean, Nothing?>() {
+    override fun visitConditionalEffectDeclaration(conditionalEffect: KtConditionalEffectDeclaration<KotlinTypeBean, Nothing?>, data: Nothing?) {
+        conditionalEffect.effect.accept(this, data)
+        buffer.append(" -> ")
+        conditionalEffect.condition.accept(this, data)
+    }
+
+    override fun visitReturnsEffectDeclaration(returnsEffect: KtReturnsEffectDeclaration<KotlinTypeBean, Nothing?>, data: Nothing?) {
+        buffer.append("Returns(")
+        returnsEffect.value.accept(this, data)
+        buffer.append(")")
+    }
+
+    override fun visitCallsEffectDeclaration(callsEffect: KtCallsEffectDeclaration<KotlinTypeBean, Nothing?>, data: Nothing?) {
+        buffer.append("CallsInPlace(")
+        callsEffect.valueParameterReference.accept(this, data)
+        buffer.append(", ${callsEffect.kind})")
+    }
+
+    override fun visitLogicalBinaryOperationContractExpression(binaryLogicExpression: KtBinaryLogicExpression<KotlinTypeBean, Nothing?>, data: Nothing?) {
+        binaryLogicExpression.left.accept(this, data)
+        buffer.append(" ${binaryLogicExpression.kind.token} ")
+        binaryLogicExpression.right.accept(this, data)
+    }
+
+    override fun visitLogicalNot(logicalNot: KtLogicalNot<KotlinTypeBean, Nothing?>, data: Nothing?) {
+        logicalNot.arg.accept(this, data)
+    }
+
+    override fun visitIsInstancePredicate(isInstancePredicate: KtIsInstancePredicate<KotlinTypeBean, Nothing?>, data: Nothing?) {
+        isInstancePredicate.arg.accept(this, data)
+        buffer.append(" ${if (isInstancePredicate.isNegated) "!" else ""}is ${isInstancePredicate.type}")
+    }
+
+    override fun visitIsNullPredicate(isNullPredicate: KtIsNullPredicate<KotlinTypeBean, Nothing?>, data: Nothing?) {
+        isNullPredicate.arg.accept(this, data)
+        buffer.append(" ${if (isNullPredicate.isNegated) "!=" else "=="} null")
+    }
+
+    override fun visitConstantDescriptor(constantReference: KtConstantReference<KotlinTypeBean, Nothing?>, data: Nothing?) {
+        buffer.append(constantReference.name)
+    }
+
+    override fun visitValueParameterReference(valueParameterReference: KtValueParameterReference<KotlinTypeBean, Nothing?>, data: Nothing?) {
+        buffer.append("param(").append(valueParameterReference.parameterIndex).append(")")
+    }
+
 }

analysis/decompiled/decompiler-to-file-stubs/tests/org/jetbrains/kotlin/analysis/decompiler/stub/files/AdditionalStubInfoTestGenerated.java

@@ -30,6 +30,12 @@ public class AdditionalStubInfoTestGenerated extends AbstractAdditionalStubInfoT
         runTest("analysis/decompiled/decompiler-to-file-stubs/testData/additionalClsStubInfo/AnnotatedFlexibleTypes/");
     }
 
+    @Test
+    @TestMetadata("Contracts")
+    public void testContracts() throws Exception {
+        runTest("analysis/decompiled/decompiler-to-file-stubs/testData/additionalClsStubInfo/Contracts/");
+    }
+
     @Test
     @TestMetadata("OuterClassesWithFlexibleArgs")
     public void testOuterClassesWithFlexibleArgs() throws Exception {

analysis/decompiled/decompiler-to-stubs/src/org/jetbrains/kotlin/analysis/decompiler/stub/CallableClsStubBuilder.kt

@@ -19,6 +19,7 @@ import org.jetbrains.kotlin.resolve.DataClassResolver
 import org.jetbrains.kotlin.serialization.deserialization.AnnotatedCallableKind
 import org.jetbrains.kotlin.serialization.deserialization.ProtoContainer
 import org.jetbrains.kotlin.serialization.deserialization.getName
+import org.jetbrains.kotlin.utils.addToStdlib.runIf
 
 fun createPackageDeclarationsStubs(
     parentStub: StubElement<out PsiElement>,
@@ -173,6 +174,7 @@ private class FunctionClsStubBuilder(
         // Note that arguments passed to stubs here and elsewhere are based on what stabs would be generated based on decompiled code
         // As functions are never decompiled to fun f() = 1 form, hasBlockBody is always true
         // This info is anyway irrelevant for the purposes these stubs are used
+        val hasContract = functionProto.hasContract()
         return KotlinFunctionStubImpl(
             parent,
             callableName.ref(),
@@ -182,7 +184,10 @@ private class FunctionClsStubBuilder(
             hasBlockBody = true,
             hasBody = Flags.MODALITY.get(functionProto.flags) != Modality.ABSTRACT,
             hasTypeParameterListBeforeFunctionName = functionProto.typeParameterList.isNotEmpty(),
-            mayHaveContract = functionProto.hasContract()
+            mayHaveContract = hasContract,
+            runIf(hasContract) {
+                ClsContractBuilder(c, typeStubBuilder).loadContract(functionProto)
+            }
         )
     }
 }

analysis/decompiled/decompiler-to-stubs/src/org/jetbrains/kotlin/analysis/decompiler/stub/ClsContractBuilder.kt

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2010-2023 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.analysis.decompiler.stub
+
+import org.jetbrains.kotlin.contracts.description.KtBooleanValueParameterReference
+import org.jetbrains.kotlin.contracts.description.KtConstantReference
+import org.jetbrains.kotlin.contracts.description.KtEffectDeclaration
+import org.jetbrains.kotlin.contracts.description.KtValueParameterReference
+import org.jetbrains.kotlin.metadata.ProtoBuf
+import org.jetbrains.kotlin.metadata.deserialization.isInstanceType
+import org.jetbrains.kotlin.name.StandardClassIds
+import org.jetbrains.kotlin.psi.stubs.impl.*
+import org.jetbrains.kotlin.psi.stubs.impl.KotlinContractEffectType.Companion.IGNORE_REFERENCE_PARAMETER_NAME
+import org.jetbrains.kotlin.serialization.deserialization.ProtoBufContractDeserializer
+import org.jetbrains.kotlin.serialization.deserialization.getClassId
+
+class ClsContractBuilder(private val c: ClsStubBuilderContext, private val typeStubBuilder: TypeClsStubBuilder) :
+    ProtoBufContractDeserializer<KotlinTypeBean, Nothing?, ProtoBuf.Function>() {
+
+    fun loadContract(proto: ProtoBuf.Function): List<KtEffectDeclaration<KotlinTypeBean, Nothing?>>? {
+        return proto.contract.effectList.map { loadPossiblyConditionalEffect(it, proto) ?: return null }
+    }
+
+    override fun extractVariable(valueParameterIndex: Int, owner: ProtoBuf.Function): KtValueParameterReference<KotlinTypeBean, Nothing?> {
+        val type = if (valueParameterIndex < 0) {
+            owner.receiverType
+        } else owner.valueParameterList[valueParameterIndex].type
+        return if (type.hasClassName() && c.nameResolver.getClassId(type.className) == StandardClassIds.Boolean) {
+            KtBooleanValueParameterReference(valueParameterIndex, name = IGNORE_REFERENCE_PARAMETER_NAME)
+        } else KtValueParameterReference(valueParameterIndex, name = IGNORE_REFERENCE_PARAMETER_NAME)
+    }
+
+    override fun extractType(proto: ProtoBuf.Expression): KotlinTypeBean? {
+        return typeStubBuilder.createKotlinTypeBean(proto.isInstanceType(c.typeTable))
+    }
+
+    override fun loadConstant(value: ProtoBuf.Expression.ConstantValue): KtConstantReference<KotlinTypeBean, Nothing?> {
+        return when (value) {
+            ProtoBuf.Expression.ConstantValue.TRUE -> KotlinContractConstantValues.TRUE
+            ProtoBuf.Expression.ConstantValue.FALSE -> KotlinContractConstantValues.FALSE
+            ProtoBuf.Expression.ConstantValue.NULL -> KotlinContractConstantValues.NULL
+        }
+    }
+
+    override fun getNotNull(): KtConstantReference<KotlinTypeBean, Nothing?> {
+        return KotlinContractConstantValues.NOT_NULL
+    }
+
+    override fun getWildcard(): KtConstantReference<KotlinTypeBean, Nothing?> {
+        return KotlinContractConstantValues.WILDCARD
+    }
+}

analysis/decompiled/decompiler-to-stubs/src/org/jetbrains/kotlin/analysis/decompiler/stub/TypeClsStubBuilder.kt

@@ -150,7 +150,7 @@ class TypeClsStubBuilder(private val c: ClsStubBuilderContext) {
         }
     }
 
-    private fun createKotlinTypeBean(
+    fun createKotlinTypeBean(
         type: Type?
     ): KotlinTypeBean? {
         if (type == null) return null

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

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.fir.analysis.checkers.declaration
 
 import org.jetbrains.kotlin.KtRealSourceElementKind
+import org.jetbrains.kotlin.contracts.description.*
 import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.diagnostics.DiagnosticReporter
 import org.jetbrains.kotlin.diagnostics.reportOn
@@ -19,6 +20,7 @@ import org.jetbrains.kotlin.fir.declarations.FirFunction
 import org.jetbrains.kotlin.fir.declarations.FirPropertyAccessor
 import org.jetbrains.kotlin.fir.declarations.utils.*
 import org.jetbrains.kotlin.fir.diagnostics.ConeDiagnostic
+import org.jetbrains.kotlin.fir.types.ConeKotlinType
 
 object FirContractChecker : FirFunctionChecker() {
     private val EMPTY_CONTRACT_MESSAGE = "Empty contract block is not allowed"
@@ -66,7 +68,7 @@ object FirContractChecker : FirFunctionChecker() {
         else if (declaration.symbol.callableId.isLocal || declaration.visibility == Visibilities.Local) contractNotAllowed("Contracts are not allowed for local functions")
     }
 
-    private object DiagnosticExtractor : ConeContractDescriptionVisitor<ConeDiagnostic?, Nothing?>() {
+    private object DiagnosticExtractor : KtContractDescriptionVisitor<ConeDiagnostic?, Nothing?, ConeKotlinType, ConeDiagnostic>() {
         override fun visitContractDescriptionElement(
             contractDescriptionElement: ConeContractDescriptionElement,
             data: Nothing?
@@ -90,7 +92,7 @@ object FirContractChecker : FirFunctionChecker() {
         }
 
         override fun visitErroneousCallsEffectDeclaration(
-            callsEffect: ConeErroneousCallsEffectDeclaration,
+            callsEffect: KtErroneousCallsEffectDeclaration<ConeKotlinType, ConeDiagnostic>,
             data: Nothing?
         ): ConeDiagnostic {
             return callsEffect.diagnostic
@@ -112,7 +114,7 @@ object FirContractChecker : FirFunctionChecker() {
         }
 
         override fun visitErroneousIsInstancePredicate(
-            isInstancePredicate: ConeErroneousIsInstancePredicate,
+            isInstancePredicate: KtErroneousIsInstancePredicate<ConeKotlinType, ConeDiagnostic>,
             data: Nothing?
         ): ConeDiagnostic {
             return isInstancePredicate.diagnostic
@@ -123,20 +125,20 @@ object FirContractChecker : FirFunctionChecker() {
         }
 
         override fun visitErroneousConstantReference(
-            erroneousConstantReference: ConeErroneousConstantReference,
+            erroneousConstantReference: KtErroneousConstantReference<ConeKotlinType, ConeDiagnostic>,
             data: Nothing?
         ): ConeDiagnostic {
             return erroneousConstantReference.diagnostic
         }
 
         override fun visitErroneousValueParameterReference(
-            valueParameterReference: ConeErroneousValueParameterReference,
+            valueParameterReference: KtErroneousValueParameterReference<ConeKotlinType, ConeDiagnostic>,
             data: Nothing?
         ): ConeDiagnostic {
             return valueParameterReference.diagnostic
         }
 
-        override fun visitErroneousElement(element: ConeErroneousContractElement, data: Nothing?): ConeDiagnostic {
+        override fun visitErroneousElement(element: KtErroneousContractElement<ConeKotlinType, ConeDiagnostic>, data: Nothing?): ConeDiagnostic {
             return element.diagnostic
         }
     }

compiler/fir/fir-deserialization/src/org/jetbrains/kotlin/fir/deserialization/FirContractDeserializer.kt

@@ -5,22 +5,24 @@
 
 package org.jetbrains.kotlin.fir.deserialization
 
-import org.jetbrains.kotlin.contracts.description.EventOccurrencesRange
+import org.jetbrains.kotlin.contracts.description.KtBooleanValueParameterReference
+import org.jetbrains.kotlin.contracts.description.KtConstantReference
+import org.jetbrains.kotlin.contracts.description.KtValueParameterReference
 import org.jetbrains.kotlin.fir.contracts.FirContractDescription
 import org.jetbrains.kotlin.fir.contracts.builder.buildResolvedContractDescription
 import org.jetbrains.kotlin.fir.contracts.description.*
 import org.jetbrains.kotlin.fir.contracts.toFirElement
 import org.jetbrains.kotlin.fir.declarations.FirContractDescriptionOwner
 import org.jetbrains.kotlin.fir.declarations.FirSimpleFunction
-import org.jetbrains.kotlin.fir.expressions.LogicOperationKind
+import org.jetbrains.kotlin.fir.diagnostics.ConeDiagnostic
 import org.jetbrains.kotlin.fir.types.ConeKotlinType
 import org.jetbrains.kotlin.fir.types.isBoolean
 import org.jetbrains.kotlin.metadata.ProtoBuf
-import org.jetbrains.kotlin.metadata.deserialization.Flags
 import org.jetbrains.kotlin.metadata.deserialization.isInstanceType
-import org.jetbrains.kotlin.utils.addIfNotNull
+import org.jetbrains.kotlin.serialization.deserialization.ProtoBufContractDeserializer
 
-class FirContractDeserializer(private val c: FirDeserializationContext) {
+class FirContractDeserializer(private val c: FirDeserializationContext) :
+    ProtoBufContractDeserializer<ConeKotlinType, ConeDiagnostic, FirContractDescriptionOwner>() {
     fun loadContract(proto: ProtoBuf.Contract, owner: FirContractDescriptionOwner): FirContractDescription? {
         val effects = proto.effectList.map { loadPossiblyConditionalEffect(it, owner) ?: return null }
         return buildResolvedContractDescription {
@@ -28,105 +30,16 @@ class FirContractDeserializer(private val c: FirDeserializationContext) {
         }
     }
 
-    private fun loadPossiblyConditionalEffect(
-        proto: ProtoBuf.Effect,
+    override fun extractType(proto: ProtoBuf.Expression): ConeKotlinType? {
+        return c.typeDeserializer.type(proto.isInstanceType(c.typeTable) ?: return null)
+    }
+
+    override fun extractVariable(
+        valueParameterIndex: Int,
         owner: FirContractDescriptionOwner
-    ): ConeEffectDeclaration? {
-        if (proto.hasConclusionOfConditionalEffect()) {
-            val conclusion = loadExpression(proto.conclusionOfConditionalEffect, owner) ?: return null
-            val effect = loadSimpleEffect(proto, owner) ?: return null
-            return ConeConditionalEffectDeclaration(effect, conclusion)
-        }
-        return loadSimpleEffect(proto, owner)
-    }
-
-    private fun loadSimpleEffect(proto: ProtoBuf.Effect, owner: FirContractDescriptionOwner): ConeEffectDeclaration? {
-        val type: ProtoBuf.Effect.EffectType = if (proto.hasEffectType()) proto.effectType else return null
-        return when(type) {
-            ProtoBuf.Effect.EffectType.RETURNS_CONSTANT -> {
-                val argument = proto.effectConstructorArgumentList.firstOrNull()
-                val returnValue = if (argument == null) {
-                    ConeConstantReference.WILDCARD
-                } else {
-                    loadExpression(argument, owner) as? ConeConstantReference ?: return null
-                }
-                ConeReturnsEffectDeclaration(returnValue)
-            }
-            ProtoBuf.Effect.EffectType.RETURNS_NOT_NULL -> {
-                ConeReturnsEffectDeclaration(ConeConstantReference.NOT_NULL)
-            }
-            ProtoBuf.Effect.EffectType.CALLS -> {
-                val argument = proto.effectConstructorArgumentList.firstOrNull() ?: return null
-                val callable = extractVariable(argument, owner) ?: return null
-                val invocationKind = if (proto.hasKind())
-                    proto.kind.toDescriptorInvocationKind() ?: return null
-                else
-                    EventOccurrencesRange.UNKNOWN
-                ConeCallsEffectDeclaration(callable, invocationKind)
-            }
-        }
-    }
-
-    private fun loadExpression(proto: ProtoBuf.Expression, owner: FirContractDescriptionOwner): ConeBooleanExpression? {
-        val primitiveType = getPrimitiveType(proto)
-        val primitiveExpression = extractPrimitiveExpression(proto, primitiveType, owner)
-
-        val complexType = getComplexType(proto)
-        val childs: MutableList<ConeBooleanExpression> = mutableListOf()
-        childs.addIfNotNull(primitiveExpression)
-
-        return when (complexType) {
-            ComplexExpressionType.AND_SEQUENCE -> {
-                proto.andArgumentList.mapTo(childs) { loadExpression(it, owner) ?: return null }
-                childs.reduce { acc, booleanExpression -> ConeBinaryLogicExpression(acc, booleanExpression, LogicOperationKind.AND) }
-            }
-
-            ComplexExpressionType.OR_SEQUENCE -> {
-                proto.orArgumentList.mapTo(childs) { loadExpression(it, owner) ?: return null }
-                childs.reduce { acc, booleanExpression -> ConeBinaryLogicExpression(acc, booleanExpression, LogicOperationKind.OR) }
-            }
-
-            null -> primitiveExpression
-        }
-    }
-
-    private fun extractPrimitiveExpression(proto: ProtoBuf.Expression, primitiveType: PrimitiveExpressionType?, owner: FirContractDescriptionOwner): ConeBooleanExpression? {
-        val isInverted = Flags.IS_NEGATED.get(proto.flags)
-
-        return when (primitiveType) {
-            PrimitiveExpressionType.VALUE_PARAMETER_REFERENCE, PrimitiveExpressionType.RECEIVER_REFERENCE -> {
-                (extractVariable(proto, owner) as? ConeBooleanValueParameterReference?)?.invertIfNecessary(isInverted)
-            }
-
-            PrimitiveExpressionType.CONSTANT ->
-                (loadConstant(proto.constantValue) as? ConeBooleanConstantReference)?.invertIfNecessary(isInverted)
-
-            PrimitiveExpressionType.INSTANCE_CHECK -> {
-                val variable = extractVariable(proto, owner) ?: return null
-                val type = extractType(proto) ?: return null
-                ConeIsInstancePredicate(variable, type, isInverted)
-            }
-
-            PrimitiveExpressionType.NULLABILITY_CHECK -> {
-                val variable = extractVariable(proto, owner) ?: return null
-                ConeIsNullPredicate(variable, isInverted)
-            }
-
-            null -> null
-        }
-    }
-
-    private fun ConeBooleanExpression.invertIfNecessary(shouldInvert: Boolean): ConeBooleanExpression =
-        if (shouldInvert) ConeLogicalNot(this) else this
-
-    private fun extractVariable(proto: ProtoBuf.Expression, owner: FirContractDescriptionOwner): ConeValueParameterReference? {
-        if (!proto.hasValueParameterReference()) return null
-
-        val ownerFunction = owner as FirSimpleFunction
-
-        val valueParameterIndex = proto.valueParameterReference - 1
-
+    ): KtValueParameterReference<ConeKotlinType, ConeDiagnostic>?  {
         val name: String
+        val ownerFunction = owner as FirSimpleFunction
         val typeRef = if (valueParameterIndex < 0) {
             name = "this"
             ownerFunction.receiverParameter?.typeRef
@@ -137,90 +50,24 @@ class FirContractDeserializer(private val c: FirDeserializationContext) {
         } ?: return null
 
         return if (!typeRef.isBoolean)
-            ConeValueParameterReference(valueParameterIndex, name)
+            KtValueParameterReference(valueParameterIndex, name)
         else
-            ConeBooleanValueParameterReference(valueParameterIndex, name)
+            KtBooleanValueParameterReference(valueParameterIndex, name)
     }
 
-    private fun ProtoBuf.Effect.InvocationKind.toDescriptorInvocationKind(): EventOccurrencesRange? = when (this) {
-        ProtoBuf.Effect.InvocationKind.AT_MOST_ONCE -> EventOccurrencesRange.AT_MOST_ONCE
-        ProtoBuf.Effect.InvocationKind.EXACTLY_ONCE -> EventOccurrencesRange.EXACTLY_ONCE
-        ProtoBuf.Effect.InvocationKind.AT_LEAST_ONCE -> EventOccurrencesRange.AT_LEAST_ONCE
-    }
-
-    private fun extractType(proto: ProtoBuf.Expression): ConeKotlinType? {
-        return c.typeDeserializer.type(proto.isInstanceType(c.typeTable) ?: return null)
-    }
-
-    private fun loadConstant(value: ProtoBuf.Expression.ConstantValue): ConeConstantReference? = when (value) {
-        ProtoBuf.Expression.ConstantValue.TRUE -> ConeBooleanConstantReference.TRUE
-        ProtoBuf.Expression.ConstantValue.FALSE -> ConeBooleanConstantReference.FALSE
-        ProtoBuf.Expression.ConstantValue.NULL -> ConeConstantReference.NULL
-    }
-
-
-    private fun getComplexType(proto: ProtoBuf.Expression): ComplexExpressionType? {
-        val isOrSequence = proto.orArgumentCount != 0
-        val isAndSequence = proto.andArgumentCount != 0
-        return when {
-            isOrSequence && isAndSequence -> null
-            isOrSequence -> ComplexExpressionType.OR_SEQUENCE
-            isAndSequence -> ComplexExpressionType.AND_SEQUENCE
-            else -> null
+    override fun loadConstant(value: ProtoBuf.Expression.ConstantValue): KtConstantReference<ConeKotlinType, ConeDiagnostic> {
+        return when (value) {
+            ProtoBuf.Expression.ConstantValue.TRUE -> ConeContractConstantValues.TRUE
+            ProtoBuf.Expression.ConstantValue.FALSE -> ConeContractConstantValues.FALSE
+            ProtoBuf.Expression.ConstantValue.NULL -> ConeContractConstantValues.NULL
         }
     }
 
-    private fun getPrimitiveType(proto: ProtoBuf.Expression): PrimitiveExpressionType? {
-        // Expected to be one element, but can be empty (unknown expression) or contain several elements (invalid data)
-        val expressionTypes: MutableList<PrimitiveExpressionType> = mutableListOf()
-
-        // Check for predicates
-        when {
-            proto.hasValueParameterReference() && proto.hasType() ->
-                expressionTypes.add(PrimitiveExpressionType.INSTANCE_CHECK)
-
-            proto.hasValueParameterReference() && Flags.IS_NULL_CHECK_PREDICATE.get(proto.flags) ->
-                expressionTypes.add(PrimitiveExpressionType.NULLABILITY_CHECK)
-        }
-
-        // If message contains correct predicate, then predicate's type overrides type of value,
-        // even is message has one
-        if (expressionTypes.isNotEmpty()) {
-            return expressionTypes.singleOrNull()
-        }
-
-        // Otherwise, check if it is a value
-        when {
-            proto.hasValueParameterReference() && proto.valueParameterReference > 0 ->
-                expressionTypes.add(PrimitiveExpressionType.VALUE_PARAMETER_REFERENCE)
-
-            proto.hasValueParameterReference() && proto.valueParameterReference == 0 ->
-                expressionTypes.add(PrimitiveExpressionType.RECEIVER_REFERENCE)
-
-            proto.hasConstantValue() -> expressionTypes.add(PrimitiveExpressionType.CONSTANT)
-        }
-
-        return expressionTypes.singleOrNull()
+    override fun getNotNull(): KtConstantReference<ConeKotlinType, ConeDiagnostic> {
+        return ConeContractConstantValues.NOT_NULL
     }
 
-    private fun ProtoBuf.Expression.hasType(): Boolean = this.hasIsInstanceType() || this.hasIsInstanceTypeId()
-
-    // Arguments of expressions with such types are never other expressions
-    private enum class PrimitiveExpressionType {
-        VALUE_PARAMETER_REFERENCE,
-        RECEIVER_REFERENCE,
-        CONSTANT,
-        INSTANCE_CHECK,
-        NULLABILITY_CHECK
-    }
-
-    // Expressions with such type can take other expressions as arguments.
-    // Additionally, for performance reasons, "complex expression" and "primitive expression"
-    // can co-exist in the one and the same message. If "primitive expression" is present
-    // in the current message, it is treated as the first argument of "complex expression".
-    private enum class ComplexExpressionType {
-        AND_SEQUENCE,
-        OR_SEQUENCE
-
+    override fun getWildcard(): KtConstantReference<ConeKotlinType, ConeDiagnostic> {
+        return ConeContractConstantValues.WILDCARD
     }
 }

compiler/fir/fir-serialization/src/org/jetbrains/kotlin/fir/serialization/FirContractSerializer.kt

@@ -6,12 +6,15 @@
 package org.jetbrains.kotlin.fir.serialization
 
 import org.jetbrains.kotlin.contracts.description.EventOccurrencesRange
+import org.jetbrains.kotlin.contracts.description.KtContractDescriptionVisitor
+import org.jetbrains.kotlin.contracts.description.LogicOperationKind
 import org.jetbrains.kotlin.fir.contracts.FirContractDescription
 import org.jetbrains.kotlin.fir.contracts.description.*
 import org.jetbrains.kotlin.fir.contracts.effects
 import org.jetbrains.kotlin.fir.declarations.FirFunction
 import org.jetbrains.kotlin.fir.declarations.FirSimpleFunction
-import org.jetbrains.kotlin.fir.expressions.LogicOperationKind
+import org.jetbrains.kotlin.fir.diagnostics.ConeDiagnostic
+import org.jetbrains.kotlin.fir.types.ConeKotlinType
 import org.jetbrains.kotlin.metadata.ProtoBuf
 import org.jetbrains.kotlin.metadata.deserialization.Flags
 
@@ -57,9 +60,9 @@ class FirContractSerializer {
 
                 is ConeReturnsEffectDeclaration -> {
                     when (effectDeclaration.value) {
-                        ConeConstantReference.NOT_NULL ->
+                        ConeContractConstantValues.NOT_NULL ->
                             builder.effectType = ProtoBuf.Effect.EffectType.RETURNS_NOT_NULL
-                        ConeConstantReference.WILDCARD ->
+                        ConeContractConstantValues.WILDCARD ->
                             builder.effectType = ProtoBuf.Effect.EffectType.RETURNS_CONSTANT
                         else -> {
                             builder.effectType = ProtoBuf.Effect.EffectType.RETURNS_CONSTANT
@@ -89,7 +92,7 @@ class FirContractSerializer {
             contractDescriptionElement: ConeContractDescriptionElement,
             contractDescription: FirContractDescription
         ): ProtoBuf.Expression.Builder {
-            return contractDescriptionElement.accept(object : ConeContractDescriptionVisitor<ProtoBuf.Expression.Builder, Unit>() {
+            return contractDescriptionElement.accept(object : KtContractDescriptionVisitor<ProtoBuf.Expression.Builder, Unit, ConeKotlinType, ConeDiagnostic>() {
                 override fun visitLogicalBinaryOperationContractExpression(
                     binaryLogicExpression: ConeBinaryLogicExpression,
                     data: Unit
@@ -201,14 +204,14 @@ class FirContractSerializer {
 
         private fun constantValueProtobufEnum(constantReference: ConeConstantReference): ProtoBuf.Expression.ConstantValue? =
             when (constantReference) {
-                ConeBooleanConstantReference.TRUE -> ProtoBuf.Expression.ConstantValue.TRUE
-                ConeBooleanConstantReference.FALSE -> ProtoBuf.Expression.ConstantValue.FALSE
-                ConeConstantReference.NULL -> ProtoBuf.Expression.ConstantValue.NULL
-                ConeConstantReference.NOT_NULL -> throw IllegalStateException(
+                ConeContractConstantValues.TRUE -> ProtoBuf.Expression.ConstantValue.TRUE
+                ConeContractConstantValues.FALSE -> ProtoBuf.Expression.ConstantValue.FALSE
+                ConeContractConstantValues.NULL -> ProtoBuf.Expression.ConstantValue.NULL
+                ConeContractConstantValues.NOT_NULL -> throw IllegalStateException(
                     "Internal error during serialization of function contract: NOT_NULL constant isn't denotable in protobuf format. " +
                             "Its serialization should be handled at higher level"
                 )
-                ConeConstantReference.WILDCARD -> null
+                ConeContractConstantValues.WILDCARD -> null
                 else -> throw IllegalArgumentException("Unknown constant: $constantReference")
             }
     }

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrVisitor.kt

@@ -10,6 +10,7 @@ import org.jetbrains.kotlin.KtFakeSourceElementKind
 import org.jetbrains.kotlin.KtNodeTypes
 import org.jetbrains.kotlin.KtPsiSourceElement
 import org.jetbrains.kotlin.KtSourceElement
+import org.jetbrains.kotlin.contracts.description.LogicOperationKind
 import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.descriptors.Visibilities

compiler/fir/raw-fir/raw-fir.common/src/org/jetbrains/kotlin/fir/builder/ConversionUtils.kt

@@ -8,6 +8,7 @@ package org.jetbrains.kotlin.fir.builder
 import com.intellij.psi.tree.IElementType
 import org.jetbrains.kotlin.KtFakeSourceElementKind
 import org.jetbrains.kotlin.KtSourceElement
+import org.jetbrains.kotlin.contracts.description.LogicOperationKind
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.descriptors.annotations.AnnotationUseSiteTarget

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/FirDataFlowAnalyzer.kt

@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.fir.resolve.dfa
 
+import org.jetbrains.kotlin.contracts.description.LogicOperationKind
 import org.jetbrains.kotlin.contracts.description.canBeRevisited
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.fir.*

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/cfg/ControlFlowGraphBuilder.kt

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.fir.resolve.dfa.cfg
 
 import org.jetbrains.kotlin.contracts.description.*
+import org.jetbrains.kotlin.contracts.description.LogicOperationKind
 import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.declarations.utils.hasExplicitBackingField

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/FirWhenExhaustivenessTransformer.kt

@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.fir.resolve.transformers
 
+import org.jetbrains.kotlin.contracts.description.LogicOperationKind
 import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.diagnostics.WhenMissingCase
@@ -12,7 +13,6 @@ import org.jetbrains.kotlin.fir.*
 import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.declarations.utils.modality
 import org.jetbrains.kotlin.fir.expressions.*
-import org.jetbrains.kotlin.fir.expressions.LogicOperationKind.OR
 import org.jetbrains.kotlin.fir.expressions.impl.FirElseIfTrueCondition
 import org.jetbrains.kotlin.fir.resolve.BodyResolveComponents
 import org.jetbrains.kotlin.fir.resolve.fullyExpandedType
@@ -182,7 +182,7 @@ private sealed class WhenExhaustivenessChecker {
         }
 
         override fun visitBinaryLogicExpression(binaryLogicExpression: FirBinaryLogicExpression, data: D) {
-            if (binaryLogicExpression.kind == OR) {
+            if (binaryLogicExpression.kind == LogicOperationKind.OR) {
                 binaryLogicExpression.acceptChildren(this, data)
             }
         }

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/contracts/ConeEffectExtractor.kt

@@ -5,11 +5,13 @@
 
 package org.jetbrains.kotlin.fir.resolve.transformers.contracts
 
-import org.jetbrains.kotlin.contracts.description.EventOccurrencesRange
+import org.jetbrains.kotlin.contracts.description.*
+import org.jetbrains.kotlin.contracts.description.LogicOperationKind
 import org.jetbrains.kotlin.fir.FirElement
 import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.contracts.description.*
 import org.jetbrains.kotlin.fir.declarations.*
+import org.jetbrains.kotlin.fir.diagnostics.ConeDiagnostic
 import org.jetbrains.kotlin.fir.expressions.*
 import org.jetbrains.kotlin.fir.references.FirNamedReference
 import org.jetbrains.kotlin.fir.resolve.diagnostics.ConeContractDescriptionError
@@ -37,8 +39,8 @@ class ConeEffectExtractor(
         private val BOOLEAN_NOT = FirContractsDslNames.id("kotlin", "Boolean", "not")
     }
 
-    private fun ConeContractDescriptionError.asElement(): ConeErroneousContractElement {
-        return ConeErroneousContractElement(this)
+    private fun ConeContractDescriptionError.asElement(): KtErroneousContractElement<ConeKotlinType, ConeDiagnostic> {
+        return KtErroneousContractElement(this)
     }
 
     override fun visitElement(element: FirElement, data: Nothing?): ConeContractDescriptionElement {
@@ -63,18 +65,19 @@ class ConeEffectExtractor(
             FirContractsDslNames.RETURNS -> {
                 val argument = functionCall.arguments.firstOrNull()
                 val value = if (argument == null) {
-                    ConeConstantReference.WILDCARD
+                    ConeContractConstantValues.WILDCARD
                 } else {
                     when (val value = argument.asContractElement()) {
                         is ConeConstantReference -> value
-                        else -> ConeErroneousConstantReference(ConeContractDescriptionError.NotAConstant(value))
+                        else -> KtErroneousConstantReference(ConeContractDescriptionError.NotAConstant(value))
                     }
                 }
-                ConeReturnsEffectDeclaration(value)
+                @Suppress("UNCHECKED_CAST")
+                KtReturnsEffectDeclaration(value as ConeConstantReference)
             }
 
             FirContractsDslNames.RETURNS_NOT_NULL -> {
-                ConeReturnsEffectDeclaration(ConeConstantReference.NOT_NULL)
+                ConeReturnsEffectDeclaration(ConeContractConstantValues.NOT_NULL)
             }
 
             FirContractsDslNames.CALLS_IN_PLACE -> {
@@ -82,7 +85,7 @@ class ConeEffectExtractor(
                 when (val argument = functionCall.arguments.getOrNull(1)) {
                     null -> ConeCallsEffectDeclaration(reference, EventOccurrencesRange.UNKNOWN)
                     else -> when (val kind = argument.parseInvocationKind()) {
-                        null -> ConeErroneousCallsEffectDeclaration(reference, ConeContractDescriptionError.UnresolvedInvocationKind(argument))
+                        null -> KtErroneousCallsEffectDeclaration(reference, ConeContractDescriptionError.UnresolvedInvocationKind(argument))
                         else -> ConeCallsEffectDeclaration(reference, kind)
                     }
                 }
@@ -146,10 +149,10 @@ class ConeEffectExtractor(
                 return ConeContractDescriptionError.UnresolvedCall(name).asElement()
             }
         val parameter = symbol.fir as? FirValueParameter
-            ?: return ConeErroneousValueParameterReference(
+            ?: return KtErroneousValueParameterReference(
                 ConeContractDescriptionError.IllegalParameter(symbol, "$symbol is not a value parameter")
             )
-        val index = valueParameters.indexOf(parameter).takeUnless { it < 0 } ?: return ConeErroneousValueParameterReference(
+        val index = valueParameters.indexOf(parameter).takeUnless { it < 0 } ?: return KtErroneousValueParameterReference(
             ConeContractDescriptionError.IllegalParameter(symbol, "Value paramter $symbol is not found in parameters of outer function")
         )
         val type = parameter.returnTypeRef.coneType
@@ -200,10 +203,10 @@ class ConeEffectExtractor(
 
     override fun <T> visitConstExpression(constExpression: FirConstExpression<T>, data: Nothing?): ConeContractDescriptionElement {
         return when (constExpression.kind) {
-            ConstantValueKind.Null -> ConeConstantReference.NULL
+            ConstantValueKind.Null -> ConeContractConstantValues.NULL
             ConstantValueKind.Boolean -> when (constExpression.value as Boolean) {
-                true -> ConeBooleanConstantReference.TRUE
-                false -> ConeBooleanConstantReference.FALSE
+                true -> ConeContractConstantValues.TRUE
+                false -> ConeContractConstantValues.FALSE
             }
             else -> ConeContractDescriptionError.IllegalConst(constExpression, onlyNullAllowed = false).asElement()
         }
@@ -224,7 +227,7 @@ class ConeEffectExtractor(
         }
         return when (diagnostic) {
             null -> ConeIsInstancePredicate(arg, type, isNegated)
-            else -> ConeErroneousIsInstancePredicate(arg, type, isNegated, diagnostic)
+            else -> KtErroneousIsInstancePredicate(arg, type, isNegated, diagnostic)
         }
     }
 
@@ -240,11 +243,11 @@ class ConeEffectExtractor(
         }
     }
 
-    private fun noReceiver(callableId: CallableId): ConeErroneousContractElement {
+    private fun noReceiver(callableId: CallableId): KtErroneousContractElement<ConeKotlinType, ConeDiagnostic> {
         return ConeContractDescriptionError.NoReceiver(callableId.callableName).asElement()
     }
 
-    private fun noArgument(callableId: CallableId): ConeErroneousContractElement {
+    private fun noArgument(callableId: CallableId): KtErroneousContractElement<ConeKotlinType, ConeDiagnostic> {
         return ConeContractDescriptionError.NoArgument(callableId.callableName).asElement()
     }
 
@@ -262,7 +265,7 @@ class ConeEffectExtractor(
     private fun FirExpression.asContractValueExpression(): ConeValueParameterReference {
         return when (val element = asContractElement()) {
             is ConeValueParameterReference -> element
-            else -> ConeErroneousValueParameterReference(ConeContractDescriptionError.NotAParameterReference(element))
+            else -> KtErroneousValueParameterReference(ConeContractDescriptionError.NotAParameterReference(element))
         }
     }
 }

compiler/fir/semantics/src/org/jetbrains/kotlin/fir/resolve/dfa/contracts.kt

@@ -5,17 +5,20 @@
 
 package org.jetbrains.kotlin.fir.resolve.dfa
 
+import org.jetbrains.kotlin.contracts.description.LogicOperationKind
 import org.jetbrains.kotlin.fir.contracts.description.*
-import org.jetbrains.kotlin.fir.expressions.LogicOperationKind
 import org.jetbrains.kotlin.fir.resolve.substitution.ConeSubstitutor
-import org.jetbrains.kotlin.fir.types.*
+import org.jetbrains.kotlin.fir.types.canBeNull
+import org.jetbrains.kotlin.fir.types.isAny
+import org.jetbrains.kotlin.fir.types.isMarkedNullable
+import org.jetbrains.kotlin.fir.types.isNullableNothing
 
 fun ConeConstantReference.toOperation(): Operation? = when (this) {
-    ConeConstantReference.WILDCARD -> null
-    ConeConstantReference.NULL -> Operation.EqNull
-    ConeConstantReference.NOT_NULL -> Operation.NotEqNull
-    ConeBooleanConstantReference.TRUE -> Operation.EqTrue
-    ConeBooleanConstantReference.FALSE -> Operation.EqFalse
+    ConeContractConstantValues.WILDCARD -> null
+    ConeContractConstantValues.NULL -> Operation.EqNull
+    ConeContractConstantValues.NOT_NULL -> Operation.NotEqNull
+    ConeContractConstantValues.TRUE -> Operation.EqTrue
+    ConeContractConstantValues.FALSE -> Operation.EqFalse
     else -> throw IllegalArgumentException("$this can not be transformed to Operation")
 }
 
@@ -31,7 +34,7 @@ fun LogicSystem.approveContractStatement(
 
     fun ConeBooleanExpression.visit(inverted: Boolean): TypeStatements? = when (this) {
         is ConeBooleanConstantReference ->
-            if (inverted == (this == ConeBooleanConstantReference.TRUE)) null else mapOf()
+            if (inverted == (this == ConeContractConstantValues.TRUE)) null else mapOf()
         is ConeLogicalNot -> arg.visit(inverted = !inverted)
         is ConeIsInstancePredicate ->
             arguments.getOrNull(arg.parameterIndex + 1)?.let {

compiler/fir/tree/build.gradle.kts

@@ -7,6 +7,7 @@ plugins {
 
 dependencies {
     api(project(":compiler:frontend.common"))
+    api(project(":core:compiler.common"))
     api(project(":compiler:fir:cones"))
 
     // Necessary only to store bound PsiElement inside FirElement

compiler/fir/tree/gen/org/jetbrains/kotlin/fir/expressions/FirBinaryLogicExpression.kt

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.fir.expressions
 
 import org.jetbrains.kotlin.KtSourceElement
+import org.jetbrains.kotlin.contracts.description.LogicOperationKind
 import org.jetbrains.kotlin.fir.FirElement
 import org.jetbrains.kotlin.fir.types.FirTypeRef
 import org.jetbrains.kotlin.fir.visitors.*

compiler/fir/tree/gen/org/jetbrains/kotlin/fir/expressions/builder/FirBinaryLogicExpressionBuilder.kt

@@ -9,13 +9,13 @@ package org.jetbrains.kotlin.fir.expressions.builder
 
 import kotlin.contracts.*
 import org.jetbrains.kotlin.KtSourceElement
+import org.jetbrains.kotlin.contracts.description.LogicOperationKind
 import org.jetbrains.kotlin.fir.builder.FirAnnotationContainerBuilder
 import org.jetbrains.kotlin.fir.builder.FirBuilderDsl
 import org.jetbrains.kotlin.fir.builder.toMutableOrEmpty
 import org.jetbrains.kotlin.fir.expressions.FirAnnotation
 import org.jetbrains.kotlin.fir.expressions.FirBinaryLogicExpression
 import org.jetbrains.kotlin.fir.expressions.FirExpression
-import org.jetbrains.kotlin.fir.expressions.LogicOperationKind
 import org.jetbrains.kotlin.fir.expressions.builder.FirExpressionBuilder
 import org.jetbrains.kotlin.fir.expressions.impl.FirBinaryLogicExpressionImpl
 import org.jetbrains.kotlin.fir.types.FirTypeRef

compiler/fir/tree/gen/org/jetbrains/kotlin/fir/expressions/impl/FirBinaryLogicExpressionImpl.kt

@@ -8,10 +8,10 @@
 package org.jetbrains.kotlin.fir.expressions.impl
 
 import org.jetbrains.kotlin.KtSourceElement
+import org.jetbrains.kotlin.contracts.description.LogicOperationKind
 import org.jetbrains.kotlin.fir.expressions.FirAnnotation
 import org.jetbrains.kotlin.fir.expressions.FirBinaryLogicExpression
 import org.jetbrains.kotlin.fir.expressions.FirExpression
-import org.jetbrains.kotlin.fir.expressions.LogicOperationKind
 import org.jetbrains.kotlin.fir.types.FirTypeRef
 import org.jetbrains.kotlin.fir.types.impl.FirImplicitTypeRefImplWithoutSource
 import org.jetbrains.kotlin.fir.visitors.*

compiler/fir/tree/src/org/jetbrains/kotlin/fir/contracts/description/ConeContractDescription.kt

@@ -1,22 +0,0 @@
-/*
- * Copyright 2010-2019 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.fir.contracts.description
-
-interface ConeContractDescriptionElement {
-    fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R
-
-    val erroneous: Boolean
-}
-
-abstract class ConeEffectDeclaration : ConeContractDescriptionElement {
-    override fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R =
-        contractDescriptionVisitor.visitEffectDeclaration(this, data)
-}
-
-interface ConeBooleanExpression : ConeContractDescriptionElement {
-    override fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R =
-        contractDescriptionVisitor.visitBooleanExpression(this, data)
-}

compiler/fir/tree/src/org/jetbrains/kotlin/fir/contracts/description/ConeContractDescriptionVisitor.kt

@@ -1,69 +0,0 @@
-/*
- * Copyright 2010-2019 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.fir.contracts.description
-
-
-abstract class ConeContractDescriptionVisitor<out R, in D> {
-    open fun visitContractDescriptionElement(contractDescriptionElement: ConeContractDescriptionElement, data: D): R {
-        throw IllegalStateException("Top of hierarchy reached, no overloads were found for element: $contractDescriptionElement")
-    }
-
-    // Effects
-    open fun visitEffectDeclaration(effectDeclaration: ConeEffectDeclaration, data: D): R = visitContractDescriptionElement(effectDeclaration, data)
-
-    open fun visitConditionalEffectDeclaration(conditionalEffect: ConeConditionalEffectDeclaration, data: D): R =
-        visitEffectDeclaration(conditionalEffect, data)
-
-    open fun visitReturnsEffectDeclaration(returnsEffect: ConeReturnsEffectDeclaration, data: D): R =
-        visitEffectDeclaration(returnsEffect, data)
-
-    open fun visitCallsEffectDeclaration(callsEffect: ConeCallsEffectDeclaration, data: D): R =
-        visitEffectDeclaration(callsEffect, data)
-
-    open fun visitErroneousCallsEffectDeclaration(callsEffect: ConeErroneousCallsEffectDeclaration, data: D): R =
-        visitCallsEffectDeclaration(callsEffect, data)
-
-    // Expressions
-    open fun visitBooleanExpression(booleanExpression: ConeBooleanExpression, data: D): R =
-        visitContractDescriptionElement(booleanExpression, data)
-
-    open fun visitLogicalBinaryOperationContractExpression(binaryLogicExpression: ConeBinaryLogicExpression, data: D): R =
-        visitBooleanExpression(binaryLogicExpression, data)
-
-    open fun visitLogicalNot(logicalNot: ConeLogicalNot, data: D): R = visitBooleanExpression(logicalNot, data)
-
-    open fun visitIsInstancePredicate(isInstancePredicate: ConeIsInstancePredicate, data: D): R =
-        visitBooleanExpression(isInstancePredicate, data)
-
-    open fun visitErroneousIsInstancePredicate(isInstancePredicate: ConeErroneousIsInstancePredicate, data: D): R =
-        visitIsInstancePredicate(isInstancePredicate, data)
-
-    open fun visitIsNullPredicate(isNullPredicate: ConeIsNullPredicate, data: D): R = visitBooleanExpression(isNullPredicate, data)
-
-    // Values
-    open fun visitValue(value: ConeContractDescriptionValue, data: D): R = visitContractDescriptionElement(value, data)
-
-    open fun visitConstantDescriptor(constantReference: ConeConstantReference, data: D): R = visitValue(constantReference, data)
-
-    open fun visitBooleanConstantDescriptor(booleanConstantDescriptor: ConeBooleanConstantReference, data: D): R =
-        visitConstantDescriptor(booleanConstantDescriptor, data)
-
-    open fun visitErroneousConstantReference(erroneousConstantReference: ConeErroneousConstantReference, data: D): R =
-        visitConstantDescriptor(erroneousConstantReference, data)
-
-    open fun visitValueParameterReference(valueParameterReference: ConeValueParameterReference, data: D): R =
-        visitValue(valueParameterReference, data)
-
-    open fun visitBooleanValueParameterReference(booleanValueParameterReference: ConeBooleanValueParameterReference, data: D): R =
-        visitValueParameterReference(booleanValueParameterReference, data)
-
-    open fun visitErroneousValueParameterReference(valueParameterReference: ConeErroneousValueParameterReference, data: D): R =
-        visitValueParameterReference(valueParameterReference, data)
-
-    // Error
-    open fun visitErroneousElement(element: ConeErroneousContractElement, data: D): R =
-        visitContractDescriptionElement(element, data)
-}

compiler/fir/tree/src/org/jetbrains/kotlin/fir/contracts/description/ConeContractRenderer.kt

@@ -5,14 +5,17 @@
 
 package org.jetbrains.kotlin.fir.contracts.description
 
+import org.jetbrains.kotlin.contracts.description.*
 import org.jetbrains.kotlin.fir.contracts.*
 import org.jetbrains.kotlin.fir.contracts.impl.FirEmptyContractDescription
 import org.jetbrains.kotlin.fir.declarations.FirContractDescriptionOwner
 import org.jetbrains.kotlin.fir.declarations.FirDeclaration
+import org.jetbrains.kotlin.fir.diagnostics.ConeDiagnostic
 import org.jetbrains.kotlin.fir.renderer.FirRendererComponents
+import org.jetbrains.kotlin.fir.types.ConeKotlinType
 import org.jetbrains.kotlin.fir.types.renderForDebugging
 
-class ConeContractRenderer : ConeContractDescriptionVisitor<Unit, Nothing?>() {
+class ConeContractRenderer : KtContractDescriptionVisitor<Unit, Nothing?, ConeKotlinType, ConeDiagnostic>() {
 
     internal lateinit var components: FirRendererComponents
     private val printer get() = components.printer
@@ -74,54 +77,54 @@ class ConeContractRenderer : ConeContractDescriptionVisitor<Unit, Nothing?>() {
         printer.println(">")
     }
 
-    override fun visitConditionalEffectDeclaration(conditionalEffect: ConeConditionalEffectDeclaration, data: Nothing?) {
+    override fun visitConditionalEffectDeclaration(conditionalEffect: KtConditionalEffectDeclaration<ConeKotlinType, ConeDiagnostic>, data: Nothing?) {
         conditionalEffect.effect.accept(this, data)
         printer.print(" -> ")
         conditionalEffect.condition.accept(this, data)
     }
 
-    override fun visitReturnsEffectDeclaration(returnsEffect: ConeReturnsEffectDeclaration, data: Nothing?) {
+    override fun visitReturnsEffectDeclaration(returnsEffect: KtReturnsEffectDeclaration<ConeKotlinType, ConeDiagnostic>, data: Nothing?) {
         printer.print("Returns(")
         returnsEffect.value.accept(this, data)
         printer.print(")")
     }
 
-    override fun visitCallsEffectDeclaration(callsEffect: ConeCallsEffectDeclaration, data: Nothing?) {
+    override fun visitCallsEffectDeclaration(callsEffect: KtCallsEffectDeclaration<ConeKotlinType, ConeDiagnostic>, data: Nothing?) {
         printer.print("CallsInPlace(")
         callsEffect.valueParameterReference.accept(this, data)
         printer.print(", ${callsEffect.kind})")
     }
 
-    override fun visitLogicalBinaryOperationContractExpression(binaryLogicExpression: ConeBinaryLogicExpression, data: Nothing?) {
+    override fun visitLogicalBinaryOperationContractExpression(binaryLogicExpression: KtBinaryLogicExpression<ConeKotlinType, ConeDiagnostic>, data: Nothing?) {
         inBracketsIfNecessary(binaryLogicExpression, binaryLogicExpression.left) { binaryLogicExpression.left.accept(this, data) }
         printer.print(" ${binaryLogicExpression.kind.token} ")
         inBracketsIfNecessary(binaryLogicExpression, binaryLogicExpression.right) { binaryLogicExpression.right.accept(this, data) }
     }
 
-    override fun visitLogicalNot(logicalNot: ConeLogicalNot, data: Nothing?) {
+    override fun visitLogicalNot(logicalNot: KtLogicalNot<ConeKotlinType, ConeDiagnostic>, data: Nothing?) {
         inBracketsIfNecessary(logicalNot, logicalNot.arg) { printer.print("!") }
         logicalNot.arg.accept(this, data)
     }
 
-    override fun visitIsInstancePredicate(isInstancePredicate: ConeIsInstancePredicate, data: Nothing?) {
+    override fun visitIsInstancePredicate(isInstancePredicate: KtIsInstancePredicate<ConeKotlinType, ConeDiagnostic>, data: Nothing?) {
         isInstancePredicate.arg.accept(this, data)
         printer.print(" ${if (isInstancePredicate.isNegated) "!" else ""}is ${isInstancePredicate.type.renderForDebugging()}")
     }
 
-    override fun visitIsNullPredicate(isNullPredicate: ConeIsNullPredicate, data: Nothing?) {
+    override fun visitIsNullPredicate(isNullPredicate: KtIsNullPredicate<ConeKotlinType, ConeDiagnostic>, data: Nothing?) {
         isNullPredicate.arg.accept(this, data)
         printer.print(" ${if (isNullPredicate.isNegated) "!=" else "=="} null")
     }
 
-    override fun visitConstantDescriptor(constantReference: ConeConstantReference, data: Nothing?) {
+    override fun visitConstantDescriptor(constantReference: KtConstantReference<ConeKotlinType, ConeDiagnostic>, data: Nothing?) {
         printer.print(constantReference.name)
     }
 
-    override fun visitValueParameterReference(valueParameterReference: ConeValueParameterReference, data: Nothing?) {
+    override fun visitValueParameterReference(valueParameterReference: KtValueParameterReference<ConeKotlinType, ConeDiagnostic>, data: Nothing?) {
         printer.print(valueParameterReference.name)
     }
 
-    private fun inBracketsIfNecessary(parent: ConeContractDescriptionElement, child: ConeContractDescriptionElement, block: () -> Unit) {
+    private fun inBracketsIfNecessary(parent: KtContractDescriptionElement<ConeKotlinType, ConeDiagnostic>, child: KtContractDescriptionElement<ConeKotlinType, ConeDiagnostic>, block: () -> Unit) {
         if (needsBrackets(parent, child)) {
             printer.print("(")
             block()
@@ -131,12 +134,12 @@ class ConeContractRenderer : ConeContractDescriptionVisitor<Unit, Nothing?>() {
         }
     }
 
-    private fun ConeContractDescriptionElement.isAtom(): Boolean =
-        this is ConeValueParameterReference || this is ConeConstantReference || this is ConeIsNullPredicate || this is ConeIsInstancePredicate
+    private fun KtContractDescriptionElement<ConeKotlinType, ConeDiagnostic>.isAtom(): Boolean =
+        this is KtValueParameterReference || this is KtConstantReference || this is KtIsNullPredicate || this is KtIsInstancePredicate
 
-    private fun needsBrackets(parent: ConeContractDescriptionElement, child: ConeContractDescriptionElement): Boolean {
+    private fun needsBrackets(parent: KtContractDescriptionElement<ConeKotlinType, ConeDiagnostic>, child: KtContractDescriptionElement<ConeKotlinType, ConeDiagnostic>): Boolean {
         if (child.isAtom()) return false
-        if (parent is ConeLogicalNot) return true
+        if (parent is KtLogicalNot) return true
         return parent::class != child::class
     }
 }

compiler/fir/tree/src/org/jetbrains/kotlin/fir/contracts/description/ConeErroneousContractElement.kt

@@ -1,19 +0,0 @@
-/*
- * Copyright 2010-2022 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.fir.contracts.description
-
-import org.jetbrains.kotlin.fir.diagnostics.ConeDiagnostic
-
-class ConeErroneousContractElement(
-    val diagnostic: ConeDiagnostic
-) : ConeEffectDeclaration(), ConeBooleanExpression, ConeContractDescriptionValue {
-    override val erroneous: Boolean
-        get() = true
-
-    override fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R {
-        return contractDescriptionVisitor.visitErroneousElement(this, data)
-    }
-}

compiler/fir/tree/src/org/jetbrains/kotlin/fir/contracts/description/ConeLogicalCombinators.kt

@@ -1,25 +0,0 @@
-/*
- * Copyright 2010-2019 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.fir.contracts.description
-
-import org.jetbrains.kotlin.fir.expressions.LogicOperationKind
-
-class ConeBinaryLogicExpression(val left: ConeBooleanExpression, val right: ConeBooleanExpression, val kind: LogicOperationKind) : ConeBooleanExpression {
-    override val erroneous: Boolean
-        get() = left.erroneous || right.erroneous
-
-    override fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R {
-        return contractDescriptionVisitor.visitLogicalBinaryOperationContractExpression(this, data)
-    }
-}
-
-class ConeLogicalNot(val arg: ConeBooleanExpression) : ConeBooleanExpression {
-    override val erroneous: Boolean
-        get() = arg.erroneous
-
-    override fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R =
-        contractDescriptionVisitor.visitLogicalNot(this, data)
-}

compiler/fir/tree/src/org/jetbrains/kotlin/fir/contracts/description/ConePredicates.kt

@@ -1,44 +0,0 @@
-/*
- * Copyright 2010-2019 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.fir.contracts.description
-
-import org.jetbrains.kotlin.fir.diagnostics.ConeDiagnostic
-import org.jetbrains.kotlin.fir.types.ConeKotlinType
-
-open class ConeIsInstancePredicate(val arg: ConeValueParameterReference, val type: ConeKotlinType, val isNegated: Boolean) : ConeBooleanExpression {
-    override val erroneous: Boolean
-        get() = arg.erroneous
-
-    override fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R =
-        contractDescriptionVisitor.visitIsInstancePredicate(this, data)
-
-    fun negated(): ConeIsInstancePredicate =
-        ConeIsInstancePredicate(arg, type, isNegated.not())
-}
-
-class ConeErroneousIsInstancePredicate(
-    arg: ConeValueParameterReference,
-    type: ConeKotlinType,
-    isNegated: Boolean,
-    val diagnostic: ConeDiagnostic
-) : ConeIsInstancePredicate(arg, type, isNegated) {
-    override val erroneous: Boolean
-        get() = true
-
-    override fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R =
-        contractDescriptionVisitor.visitErroneousIsInstancePredicate(this, data)
-}
-
-class ConeIsNullPredicate(val arg: ConeValueParameterReference, val isNegated: Boolean) : ConeBooleanExpression {
-    override val erroneous: Boolean
-        get() = arg.erroneous
-
-    override fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R =
-        contractDescriptionVisitor.visitIsNullPredicate(this, data)
-
-    fun negated(): ConeIsNullPredicate =
-        ConeIsNullPredicate(arg, isNegated.not())
-}

compiler/fir/tree/src/org/jetbrains/kotlin/fir/contracts/description/ConeValues.kt

@@ -1,74 +1,33 @@
 /*
- * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2023 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.fir.contracts.description
 
+import org.jetbrains.kotlin.contracts.description.*
 import org.jetbrains.kotlin.fir.diagnostics.ConeDiagnostic
+import org.jetbrains.kotlin.fir.types.ConeKotlinType
 
-interface ConeContractDescriptionValue : ConeContractDescriptionElement {
-    override fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R =
-        contractDescriptionVisitor.visitValue(this, data)
+object ConeContractConstantValues {
+    val NULL = KtConstantReference<ConeKotlinType, ConeDiagnostic>("NULL")
+    val WILDCARD = KtConstantReference<ConeKotlinType, ConeDiagnostic>("WILDCARD")
+    val NOT_NULL = KtConstantReference<ConeKotlinType, ConeDiagnostic>("NOT_NULL")
+    val TRUE = KtBooleanConstantReference<ConeKotlinType, ConeDiagnostic>("TRUE")
+    val FALSE = KtBooleanConstantReference<ConeKotlinType, ConeDiagnostic>("FALSE")
 }
 
-open class ConeConstantReference protected constructor(val name: String) : ConeContractDescriptionValue {
-    override val erroneous: Boolean
-        get() = false
-
-    override fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R =
-        contractDescriptionVisitor.visitConstantDescriptor(this, data)
-
-    companion object {
-        val NULL = ConeConstantReference("NULL")
-        val WILDCARD = ConeConstantReference("WILDCARD")
-        val NOT_NULL = ConeConstantReference("NOT_NULL")
-    }
-}
-
-class ConeBooleanConstantReference private constructor(name: String) : ConeConstantReference(name), ConeBooleanExpression {
-    override fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R =
-        contractDescriptionVisitor.visitBooleanConstantDescriptor(this, data)
-
-    companion object {
-        val TRUE = ConeBooleanConstantReference("TRUE")
-        val FALSE = ConeBooleanConstantReference("FALSE")
-    }
-}
-
-class ConeErroneousConstantReference(val diagnostic: ConeDiagnostic) : ConeConstantReference("ERROR") {
-    override val erroneous: Boolean
-        get() = true
-
-    override fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R =
-        contractDescriptionVisitor.visitErroneousConstantReference(this, data)
-}
-
-/*
- * Index of value parameter of function
- * -1 means that it is reference to extension receiver
- */
-open class ConeValueParameterReference(val parameterIndex: Int, val name: String) : ConeContractDescriptionValue {
-    init {
-        assert(parameterIndex >= -1)
-    }
-
-    override val erroneous: Boolean
-        get() = false
-
-    override fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R =
-        contractDescriptionVisitor.visitValueParameterReference(this, data)
-}
-
-class ConeBooleanValueParameterReference(parameterIndex: Int, name: String) : ConeValueParameterReference(parameterIndex, name), ConeBooleanExpression {
-    override fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R =
-        contractDescriptionVisitor.visitBooleanValueParameterReference(this, data)
-}
-
-class ConeErroneousValueParameterReference(val diagnostic: ConeDiagnostic) : ConeValueParameterReference(Int.MAX_VALUE, "ERROR") {
-    override val erroneous: Boolean
-        get() = true
-
-    override fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R =
-        contractDescriptionVisitor.visitErroneousValueParameterReference(this, data)
-}
+typealias ConeEffectDeclaration = KtEffectDeclaration<ConeKotlinType, ConeDiagnostic>
+typealias ConeContractDescriptionElement = KtContractDescriptionElement<ConeKotlinType, ConeDiagnostic>
+typealias ConeCallsEffectDeclaration = KtCallsEffectDeclaration<ConeKotlinType, ConeDiagnostic>
+typealias ConeConditionalEffectDeclaration = KtConditionalEffectDeclaration<ConeKotlinType, ConeDiagnostic>
+typealias ConeReturnsEffectDeclaration = KtReturnsEffectDeclaration<ConeKotlinType, ConeDiagnostic>
+typealias ConeConstantReference = KtConstantReference<ConeKotlinType, ConeDiagnostic>
+typealias ConeIsNullPredicate = KtIsNullPredicate<ConeKotlinType, ConeDiagnostic>
+typealias ConeIsInstancePredicate = KtIsInstancePredicate<ConeKotlinType, ConeDiagnostic>
+typealias ConeLogicalNot = KtLogicalNot<ConeKotlinType, ConeDiagnostic>
+typealias ConeBooleanExpression = KtBooleanExpression<ConeKotlinType, ConeDiagnostic>
+typealias ConeBinaryLogicExpression = KtBinaryLogicExpression<ConeKotlinType, ConeDiagnostic>
+typealias ConeBooleanConstantReference = KtBooleanConstantReference<ConeKotlinType, ConeDiagnostic>
+typealias ConeValueParameterReference = KtValueParameterReference<ConeKotlinType, ConeDiagnostic>
+typealias ConeBooleanValueParameterReference = KtBooleanValueParameterReference<ConeKotlinType, ConeDiagnostic>

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/Types.kt

@@ -42,7 +42,7 @@ val smartcastStabilityType = type(SmartcastStability::class)
 val fqNameType = type(FqName::class)
 val classIdType = type(ClassId::class)
 val annotationUseSiteTargetType = type(AnnotationUseSiteTarget::class)
-val operationKindType = type("fir.expressions", "LogicOperationKind")
+val operationKindType = type("contracts.description", "LogicOperationKind")
 val coneKotlinTypeType = type(ConeKotlinType::class)
 val coneSimpleKotlinTypeType = type(ConeSimpleKotlinType::class)
 val coneClassLikeTypeType = type(ConeClassLikeType::class)

compiler/psi/src/org/jetbrains/kotlin/psi/stubs/KotlinStubVersions.kt

@@ -23,12 +23,12 @@ object KotlinStubVersions {
     // Though only kotlin declarations (no code in the bodies) are stubbed, please do increase this version
     //      if you are not 100% sure it can be avoided.
     // Increasing this version will lead to reindexing of all kotlin source files on the first IDE startup with the new version.
-    const val SOURCE_STUB_VERSION = 149
+    const val SOURCE_STUB_VERSION = 150
 
     // Binary stub version should be increased if stub format (org.jetbrains.kotlin.psi.stubs.impl) is changed
     //      or changes are made to the core stub building code (org.jetbrains.kotlin.idea.decompiler.stubBuilder).
     // Increasing this version will lead to reindexing of all binary files that are potentially kotlin binaries (including all class files).
-    private const val BINARY_STUB_VERSION = 85
+    private const val BINARY_STUB_VERSION = 86
 
     // Classfile stub version should be increased if changes are made to classfile stub building subsystem (org.jetbrains.kotlin.idea.decompiler.classFile)
     // Increasing this version will lead to reindexing of all classfiles.

compiler/psi/src/org/jetbrains/kotlin/psi/stubs/elements/KtFunctionElementType.java

@@ -51,7 +51,8 @@ public class KtFunctionElementType extends KtStubElementType<KotlinFunctionStub,
         return new KotlinFunctionStubImpl(
                 (StubElement<?>) parentStub, StringRef.fromString(psi.getName()), isTopLevel, fqName,
                 isExtension, hasBlockBody, hasBody, psi.hasTypeParameterListBeforeFunctionName(),
-                psi.mayHaveContract()
+                psi.mayHaveContract(),
+                null
         );
     }
 
@@ -67,7 +68,11 @@ public class KtFunctionElementType extends KtStubElementType<KotlinFunctionStub,
         dataStream.writeBoolean(stub.hasBlockBody());
         dataStream.writeBoolean(stub.hasBody());
         dataStream.writeBoolean(stub.hasTypeParameterListBeforeFunctionName());
-        dataStream.writeBoolean(stub.mayHaveContract());
+        boolean haveContract = stub.mayHaveContract();
+        dataStream.writeBoolean(haveContract);
+        if (haveContract && stub instanceof KotlinFunctionStubImpl) {
+            ((KotlinFunctionStubImpl) stub).serializeContract(dataStream);
+        }
     }
 
     @NotNull
@@ -84,10 +89,9 @@ public class KtFunctionElementType extends KtStubElementType<KotlinFunctionStub,
         boolean hasBody = dataStream.readBoolean();
         boolean hasTypeParameterListBeforeFunctionName = dataStream.readBoolean();
         boolean mayHaveContract = dataStream.readBoolean();
-
         return new KotlinFunctionStubImpl(
                 (StubElement<?>) parentStub, name, isTopLevel, fqName, isExtension, hasBlockBody, hasBody,
-                hasTypeParameterListBeforeFunctionName, mayHaveContract
+                hasTypeParameterListBeforeFunctionName, mayHaveContract, mayHaveContract ? KotlinFunctionStubImpl.Companion.deserializeContract(dataStream) : null
         );
     }
 

compiler/psi/src/org/jetbrains/kotlin/psi/stubs/elements/KtUserTypeElementType.java

@@ -61,7 +61,7 @@ public class KtUserTypeElementType extends KtStubElementType<KotlinUserTypeStub,
         }
     }
 
-    private static void serializeType(@NotNull StubOutputStream dataStream, @Nullable KotlinTypeBean type) throws IOException {
+    public static void serializeType(@NotNull StubOutputStream dataStream, @Nullable KotlinTypeBean type) throws IOException {
         dataStream.writeInt(KotlinTypeBeanKind.fromBean(type).ordinal());
         if (type instanceof KotlinClassTypeBean) {
             StubUtils.serializeClassId(dataStream, ((KotlinClassTypeBean) type).getClassId());
@@ -94,7 +94,7 @@ public class KtUserTypeElementType extends KtStubElementType<KotlinUserTypeStub,
     }
 
     @Nullable
-    private static KotlinTypeBean deserializeType(@NotNull StubInputStream dataStream) throws IOException {
+    public static KotlinTypeBean deserializeType(@NotNull StubInputStream dataStream) throws IOException {
         KotlinTypeBeanKind typeKind = KotlinTypeBeanKind.values()[dataStream.readInt()];
         switch (typeKind) {
             case CLASS: {

compiler/psi/src/org/jetbrains/kotlin/psi/stubs/impl/KotlinContractEffectStubImpl.kt

@@ -7,12 +7,165 @@ package org.jetbrains.kotlin.psi.stubs.impl
 
 import com.intellij.psi.PsiElement
 import com.intellij.psi.stubs.StubElement
+import com.intellij.psi.stubs.StubInputStream
+import com.intellij.psi.stubs.StubOutputStream
+import org.jetbrains.kotlin.contracts.description.*
 import org.jetbrains.kotlin.psi.KtContractEffect
 import org.jetbrains.kotlin.psi.stubs.KotlinContractEffectStub
 import org.jetbrains.kotlin.psi.stubs.elements.KtContractEffectElementType
+import org.jetbrains.kotlin.psi.stubs.elements.KtUserTypeElementType.deserializeType
+import org.jetbrains.kotlin.psi.stubs.elements.KtUserTypeElementType.serializeType
 
 class KotlinContractEffectStubImpl(
     parent: StubElement<out PsiElement>?,
     elementType: KtContractEffectElementType
-) : KotlinPlaceHolderStubImpl<KtContractEffect>(parent, elementType), KotlinContractEffectStub {
+) : KotlinPlaceHolderStubImpl<KtContractEffect>(parent, elementType), KotlinContractEffectStub
+
+enum class KotlinContractEffectType {
+    CALLS {
+        override fun deserialize(dataStream: StubInputStream): KtCallsEffectDeclaration<KotlinTypeBean, Nothing?> {
+            val declaration = PARAMETER_REFERENCE.deserialize(dataStream)
+            val range = EventOccurrencesRange.values()[dataStream.readInt()]
+            return KtCallsEffectDeclaration(declaration as KtValueParameterReference, range)
+        }
+    },
+    RETURNS {
+        override fun deserialize(dataStream: StubInputStream): KtContractDescriptionElement<KotlinTypeBean, Nothing?> {
+            return KtReturnsEffectDeclaration(CONSTANT.deserialize(dataStream) as KtConstantReference)
+        }
+    },
+    CONDITIONAL {
+        override fun deserialize(dataStream: StubInputStream): KtContractDescriptionElement<KotlinTypeBean, Nothing?> {
+            val descriptionElement = values()[dataStream.readInt()].deserialize(dataStream)
+            val condition = values()[dataStream.readInt()].deserialize(dataStream)
+            return KtConditionalEffectDeclaration(
+                descriptionElement as KtEffectDeclaration,
+                condition as KtBooleanExpression
+            )
+        }
+    },
+    IS_NULL {
+        override fun deserialize(dataStream: StubInputStream): KtContractDescriptionElement<KotlinTypeBean, Nothing?> {
+            return KtIsNullPredicate(
+                PARAMETER_REFERENCE.deserialize(dataStream) as KtValueParameterReference,
+                dataStream.readBoolean()
+            )
+        }
+    },
+    IS_INSTANCE {
+        override fun deserialize(dataStream: StubInputStream): KtContractDescriptionElement<KotlinTypeBean, Nothing?> {
+            return KtIsInstancePredicate(
+                PARAMETER_REFERENCE.deserialize(dataStream) as KtValueParameterReference,
+                deserializeType(dataStream)!!,
+                dataStream.readBoolean()
+            )
+        }
+    },
+    NOT {
+        override fun deserialize(dataStream: StubInputStream): KtContractDescriptionElement<KotlinTypeBean, Nothing?> {
+            return KtLogicalNot(values()[dataStream.readInt()].deserialize(dataStream) as KtBooleanExpression)
+        }
+    },
+    BOOLEAN_LOGIC {
+        override fun deserialize(dataStream: StubInputStream): KtContractDescriptionElement<KotlinTypeBean, Nothing?> {
+            val kind = if (dataStream.readBoolean()) LogicOperationKind.AND else LogicOperationKind.OR
+            val left = values()[dataStream.readInt()].deserialize(dataStream) as KtBooleanExpression
+            val right = values()[dataStream.readInt()].deserialize(dataStream) as KtBooleanExpression
+            return KtBinaryLogicExpression(left, right, kind)
+        }
+    },
+    PARAMETER_REFERENCE {
+        override fun deserialize(dataStream: StubInputStream): KtValueParameterReference<KotlinTypeBean, Nothing?> {
+            return KtValueParameterReference(dataStream.readInt(), IGNORE_REFERENCE_PARAMETER_NAME)
+        }
+    },
+    CONSTANT {
+        override fun deserialize(dataStream: StubInputStream): KtContractDescriptionElement<KotlinTypeBean, Nothing?> {
+            return when (val str = dataStream.readNameString()!!) {
+                "TRUE" -> KotlinContractConstantValues.TRUE
+                "FALSE" -> KotlinContractConstantValues.FALSE
+                "NULL" -> KotlinContractConstantValues.NULL
+                "NOT_NULL" -> KotlinContractConstantValues.NOT_NULL
+                "WILDCARD" -> KotlinContractConstantValues.WILDCARD
+                else -> error("Unexpected $str")
+            }
+        }
+    };
+
+    abstract fun deserialize(dataStream: StubInputStream): KtContractDescriptionElement<KotlinTypeBean, Nothing?>
+
+    companion object {
+        const val IGNORE_REFERENCE_PARAMETER_NAME = "<ignore>"
+    }
+}
+
+class KotlinContractSerializationVisitor(val dataStream: StubOutputStream) :
+    KtContractDescriptionVisitor<Unit, Nothing?, KotlinTypeBean, Nothing?>() {
+    override fun visitConditionalEffectDeclaration(
+        conditionalEffect: KtConditionalEffectDeclaration<KotlinTypeBean, Nothing?>,
+        data: Nothing?
+    ) {
+        dataStream.writeInt(KotlinContractEffectType.CONDITIONAL.ordinal)
+        conditionalEffect.effect.accept(this, data)
+        conditionalEffect.condition.accept(this, data)
+    }
+
+    override fun visitReturnsEffectDeclaration(returnsEffect: KtReturnsEffectDeclaration<KotlinTypeBean, Nothing?>, data: Nothing?) {
+        dataStream.writeInt(KotlinContractEffectType.RETURNS.ordinal)
+        returnsEffect.value.accept(this, data)
+    }
+
+    override fun visitCallsEffectDeclaration(callsEffect: KtCallsEffectDeclaration<KotlinTypeBean, Nothing?>, data: Nothing?) {
+        dataStream.writeInt(KotlinContractEffectType.CALLS.ordinal)
+        callsEffect.valueParameterReference.accept(this, data)
+        dataStream.writeInt(callsEffect.kind.ordinal)
+    }
+
+    override fun visitLogicalBinaryOperationContractExpression(
+        binaryLogicExpression: KtBinaryLogicExpression<KotlinTypeBean, Nothing?>,
+        data: Nothing?
+    ) {
+        dataStream.writeInt(KotlinContractEffectType.BOOLEAN_LOGIC.ordinal)
+        dataStream.writeBoolean(binaryLogicExpression.kind == LogicOperationKind.AND)
+        binaryLogicExpression.left.accept(this, data)
+        binaryLogicExpression.right.accept(this, data)
+    }
+
+    override fun visitLogicalNot(logicalNot: KtLogicalNot<KotlinTypeBean, Nothing?>, data: Nothing?) {
+        dataStream.writeInt(KotlinContractEffectType.NOT.ordinal)
+        logicalNot.arg.accept(this, data)
+    }
+
+    override fun visitIsInstancePredicate(isInstancePredicate: KtIsInstancePredicate<KotlinTypeBean, Nothing?>, data: Nothing?) {
+        dataStream.writeInt(KotlinContractEffectType.IS_INSTANCE.ordinal)
+        isInstancePredicate.arg.accept(this, data)
+        serializeType(dataStream, isInstancePredicate.type)
+        dataStream.writeBoolean(isInstancePredicate.isNegated)
+    }
+
+    override fun visitIsNullPredicate(isNullPredicate: KtIsNullPredicate<KotlinTypeBean, Nothing?>, data: Nothing?) {
+        dataStream.writeInt(KotlinContractEffectType.IS_NULL.ordinal)
+        isNullPredicate.arg.accept(this, data)
+        dataStream.writeBoolean(isNullPredicate.isNegated)
+    }
+
+
+    override fun visitConstantDescriptor(constantReference: KtConstantReference<KotlinTypeBean, Nothing?>, data: Nothing?) {
+        dataStream.writeInt(KotlinContractEffectType.CONSTANT.ordinal)
+        dataStream.writeName(constantReference.name)
+    }
+
+    override fun visitValueParameterReference(valueParameterReference: KtValueParameterReference<KotlinTypeBean, Nothing?>, data: Nothing?) {
+        dataStream.writeInt(KotlinContractEffectType.PARAMETER_REFERENCE.ordinal)
+        dataStream.writeInt(valueParameterReference.parameterIndex)
+    }
+}
+
+object KotlinContractConstantValues {
+    val NULL = KtConstantReference<KotlinTypeBean, Nothing?>("NULL")
+    val WILDCARD = KtConstantReference<KotlinTypeBean, Nothing?>("WILDCARD")
+    val NOT_NULL = KtConstantReference<KotlinTypeBean, Nothing?>("NOT_NULL")
+
+    val TRUE = KtBooleanConstantReference<KotlinTypeBean, Nothing?>("TRUE")
+    val FALSE = KtBooleanConstantReference<KotlinTypeBean, Nothing?>("FALSE")
 }

compiler/psi/src/org/jetbrains/kotlin/psi/stubs/impl/KotlinFunctionStubImpl.kt

@@ -16,13 +16,17 @@
 
 package org.jetbrains.kotlin.psi.stubs.impl
 
+import com.intellij.psi.PsiElement
 import com.intellij.psi.stubs.StubElement
+import com.intellij.psi.stubs.StubInputStream
+import com.intellij.psi.stubs.StubOutputStream
 import com.intellij.util.io.StringRef
+import org.jetbrains.kotlin.contracts.description.KtContractDescriptionElement
+import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.psi.KtNamedFunction
 import org.jetbrains.kotlin.psi.stubs.KotlinFunctionStub
 import org.jetbrains.kotlin.psi.stubs.elements.KtStubElementTypes
-import org.jetbrains.kotlin.name.FqName
-import com.intellij.psi.PsiElement
+import java.io.IOException
 
 class KotlinFunctionStubImpl(
     parent: StubElement<out PsiElement>?,
@@ -33,7 +37,8 @@ class KotlinFunctionStubImpl(
     private val hasBlockBody: Boolean,
     private val hasBody: Boolean,
     private val hasTypeParameterListBeforeFunctionName: Boolean,
-    private val mayHaveContract: Boolean
+    private val mayHaveContract: Boolean,
+    val contract: List<KtContractDescriptionElement<KotlinTypeBean, Nothing?>>?
 ) : KotlinStubBaseImpl<KtNamedFunction>(parent, KtStubElementTypes.FUNCTION), KotlinFunctionStub {
     init {
         if (isTopLevel && fqName == null) {
@@ -50,4 +55,24 @@ class KotlinFunctionStubImpl(
     override fun hasBody() = hasBody
     override fun hasTypeParameterListBeforeFunctionName() = hasTypeParameterListBeforeFunctionName
     override fun mayHaveContract(): Boolean = mayHaveContract
+
+    @Throws(IOException::class)
+    fun serializeContract(dataStream: StubOutputStream) {
+        val effects: List<KtContractDescriptionElement<KotlinTypeBean, Nothing?>>? = contract
+        dataStream.writeInt(effects?.size ?: 0)
+        val visitor = KotlinContractSerializationVisitor(dataStream)
+        effects?.forEach { it.accept(visitor, null) }
+    }
+
+    companion object {
+        fun deserializeContract(dataStream: StubInputStream): List<KtContractDescriptionElement<KotlinTypeBean, Nothing?>> {
+            val effects = mutableListOf<KtContractDescriptionElement<KotlinTypeBean, Nothing?>>()
+            val count: Int = dataStream.readInt()
+            for (i in 0 until count) {
+                val effectType: KotlinContractEffectType = KotlinContractEffectType.values()[dataStream.readInt()]
+                effects.add(effectType.deserialize(dataStream))
+            }
+            return effects
+        }
+    }
 }

core/compiler.common/src/org/jetbrains/kotlin/contracts/description/KtContractDescription.kt

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2010-2023 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.contracts.description
+
+interface KtContractDescriptionElement<Type, Diagnostic> {
+    fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R
+
+    val erroneous: Boolean
+}
+
+abstract class KtEffectDeclaration<Type, Diagnostic> : KtContractDescriptionElement<Type, Diagnostic> {
+    override fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R =
+        contractDescriptionVisitor.visitEffectDeclaration(this, data)
+}
+
+interface KtBooleanExpression<Type, Diagnostic> : KtContractDescriptionElement<Type, Diagnostic> {
+    override fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R =
+        contractDescriptionVisitor.visitBooleanExpression(this, data)
+}

core/compiler.common/src/org/jetbrains/kotlin/contracts/description/KtContractDescriptionVisitor.kt

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2010-2023 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.contracts.description
+
+
+abstract class KtContractDescriptionVisitor<out R, in D, Type, Diagnostic> {
+    open fun visitContractDescriptionElement(contractDescriptionElement: KtContractDescriptionElement<Type, Diagnostic>, data: D): R {
+        throw IllegalStateException("Top of hierarchy reached, no overloads were found for element: $contractDescriptionElement")
+    }
+
+    // Effects
+    open fun visitEffectDeclaration(effectDeclaration: KtEffectDeclaration<Type, Diagnostic>, data: D): R = visitContractDescriptionElement(effectDeclaration, data)
+
+    open fun visitConditionalEffectDeclaration(conditionalEffect: KtConditionalEffectDeclaration<Type, Diagnostic>, data: D): R =
+        visitEffectDeclaration(conditionalEffect, data)
+
+    open fun visitReturnsEffectDeclaration(returnsEffect: KtReturnsEffectDeclaration<Type, Diagnostic>, data: D): R =
+        visitEffectDeclaration(returnsEffect, data)
+
+    open fun visitCallsEffectDeclaration(callsEffect: KtCallsEffectDeclaration<Type, Diagnostic>, data: D): R =
+        visitEffectDeclaration(callsEffect, data)
+
+    open fun visitErroneousCallsEffectDeclaration(callsEffect: KtErroneousCallsEffectDeclaration<Type, Diagnostic>, data: D): R =
+        visitCallsEffectDeclaration(callsEffect, data)
+
+    // Expressions
+    open fun visitBooleanExpression(booleanExpression: KtBooleanExpression<Type, Diagnostic>, data: D): R =
+        visitContractDescriptionElement(booleanExpression, data)
+
+    open fun visitLogicalBinaryOperationContractExpression(binaryLogicExpression: KtBinaryLogicExpression<Type, Diagnostic>, data: D): R =
+        visitBooleanExpression(binaryLogicExpression, data)
+
+    open fun visitLogicalNot(logicalNot: KtLogicalNot<Type, Diagnostic>, data: D): R = visitBooleanExpression(logicalNot, data)
+
+    open fun visitIsInstancePredicate(isInstancePredicate: KtIsInstancePredicate<Type, Diagnostic>, data: D): R =
+        visitBooleanExpression(isInstancePredicate, data)
+
+    open fun visitErroneousIsInstancePredicate(isInstancePredicate: KtErroneousIsInstancePredicate<Type, Diagnostic>, data: D): R =
+        visitIsInstancePredicate(isInstancePredicate, data)
+
+    open fun visitIsNullPredicate(isNullPredicate: KtIsNullPredicate<Type, Diagnostic>, data: D): R = visitBooleanExpression(isNullPredicate, data)
+
+    // Values
+    open fun visitValue(value: KtContractDescriptionValue<Type, Diagnostic>, data: D): R = visitContractDescriptionElement(value, data)
+
+    open fun visitConstantDescriptor(constantReference: KtConstantReference<Type, Diagnostic>, data: D): R = visitValue(constantReference, data)
+
+    open fun visitBooleanConstantDescriptor(booleanConstantDescriptor: KtBooleanConstantReference<Type, Diagnostic>, data: D): R =
+        visitConstantDescriptor(booleanConstantDescriptor, data)
+
+    open fun visitErroneousConstantReference(erroneousConstantReference: KtErroneousConstantReference<Type, Diagnostic>, data: D): R =
+        visitConstantDescriptor(erroneousConstantReference, data)
+
+    open fun visitValueParameterReference(valueParameterReference: KtValueParameterReference<Type, Diagnostic>, data: D): R =
+        visitValue(valueParameterReference, data)
+
+    open fun visitBooleanValueParameterReference(booleanValueParameterReference: KtBooleanValueParameterReference<Type, Diagnostic>, data: D): R =
+        visitValueParameterReference(booleanValueParameterReference, data)
+
+    open fun visitErroneousValueParameterReference(valueParameterReference: KtErroneousValueParameterReference<Type, Diagnostic>, data: D): R =
+        visitValueParameterReference(valueParameterReference, data)
+
+    // Error
+    open fun visitErroneousElement(element: KtErroneousContractElement<Type, Diagnostic>, data: D): R =
+        visitContractDescriptionElement(element, data)
+}

core/compiler.common/src/org/jetbrains/kotlin/contracts/description/KtEffects.kt

@@ -1,12 +1,9 @@
 /*
- * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2023 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.fir.contracts.description
-
-import org.jetbrains.kotlin.contracts.description.EventOccurrencesRange
-import org.jetbrains.kotlin.fir.diagnostics.ConeDiagnostic
+package org.jetbrains.kotlin.contracts.description
 
 /**
  * Effect with condition attached to it.
@@ -22,11 +19,14 @@ import org.jetbrains.kotlin.fir.diagnostics.ConeDiagnostic
  *  - if [effect] wasn't observed, we *can't* reason that [condition] is false
  *  - if [condition] is true, we *can't* reason that [effect] will be observed.
  */
-class ConeConditionalEffectDeclaration(val effect: ConeEffectDeclaration, val condition: ConeBooleanExpression) : ConeEffectDeclaration() {
+class KtConditionalEffectDeclaration<Type, Diagnostic>(
+    val effect: KtEffectDeclaration<Type, Diagnostic>,
+    val condition: KtBooleanExpression<Type, Diagnostic>
+) : KtEffectDeclaration<Type, Diagnostic>() {
     override val erroneous: Boolean
         get() = effect.erroneous || condition.erroneous
 
-    override fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R =
+    override fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R =
         contractDescriptionVisitor.visitConditionalEffectDeclaration(this, data)
 }
 
@@ -34,11 +34,12 @@ class ConeConditionalEffectDeclaration(val effect: ConeEffectDeclaration, val co
 /**
  * Effect which specifies that subroutine returns some particular value
  */
-class ConeReturnsEffectDeclaration(val value: ConeConstantReference) : ConeEffectDeclaration() {
+class KtReturnsEffectDeclaration<Type, Diagnostic>(val value: KtConstantReference<Type, Diagnostic>) :
+    KtEffectDeclaration<Type, Diagnostic>() {
     override val erroneous: Boolean
         get() = value.erroneous
 
-    override fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R =
+    override fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R =
         contractDescriptionVisitor.visitReturnsEffectDeclaration(this, data)
 }
 
@@ -47,24 +48,24 @@ class ConeReturnsEffectDeclaration(val value: ConeConstantReference) : ConeEffec
  * Effect which specifies, that during execution of subroutine, callable [valueParameterReference] will be invoked
  * [kind] amount of times, and will never be invoked after subroutine call is finished.
  */
-open class ConeCallsEffectDeclaration(
-    val valueParameterReference: ConeValueParameterReference,
+open class KtCallsEffectDeclaration<Type, Diagnostic>(
+    val valueParameterReference: KtValueParameterReference<Type, Diagnostic>,
     val kind: EventOccurrencesRange
-) : ConeEffectDeclaration() {
+) : KtEffectDeclaration<Type, Diagnostic>() {
     override val erroneous: Boolean
         get() = valueParameterReference.erroneous
 
-    override fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R =
+    override fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R =
         contractDescriptionVisitor.visitCallsEffectDeclaration(this, data)
 }
 
-class ConeErroneousCallsEffectDeclaration(
-    valueParameterReference: ConeValueParameterReference,
-    val diagnostic: ConeDiagnostic
-) : ConeCallsEffectDeclaration(valueParameterReference, EventOccurrencesRange.UNKNOWN) {
+class KtErroneousCallsEffectDeclaration<Type, Diagnostic>(
+    valueParameterReference: KtValueParameterReference<Type, Diagnostic>,
+    val diagnostic: Diagnostic
+) : KtCallsEffectDeclaration<Type, Diagnostic>(valueParameterReference, EventOccurrencesRange.UNKNOWN) {
     override val erroneous: Boolean
         get() = true
 
-    override fun <R, D> accept(contractDescriptionVisitor: ConeContractDescriptionVisitor<R, D>, data: D): R =
+    override fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R =
         contractDescriptionVisitor.visitErroneousCallsEffectDeclaration(this, data)
 }

core/compiler.common/src/org/jetbrains/kotlin/contracts/description/KtErroneousContractElement.kt

@@ -0,0 +1,17 @@
+/*
+ * Copyright 2010-2023 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.contracts.description
+
+class KtErroneousContractElement<Type, Diagnostic>(
+    val diagnostic: Diagnostic
+) : KtEffectDeclaration<Type, Diagnostic>(), KtBooleanExpression<Type, Diagnostic>, KtContractDescriptionValue<Type, Diagnostic> {
+    override val erroneous: Boolean
+        get() = true
+
+    override fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R {
+        return contractDescriptionVisitor.visitErroneousElement(this, data)
+    }
+}

core/compiler.common/src/org/jetbrains/kotlin/contracts/description/KtLogicalCombinators.kt

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2010-2023 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.contracts.description
+
+class KtBinaryLogicExpression<Type, Diagnostic>(
+    val left: KtBooleanExpression<Type, Diagnostic>,
+    val right: KtBooleanExpression<Type, Diagnostic>,
+    val kind: LogicOperationKind
+) : KtBooleanExpression<Type, Diagnostic> {
+    override val erroneous: Boolean
+        get() = left.erroneous || right.erroneous
+
+    override fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R {
+        return contractDescriptionVisitor.visitLogicalBinaryOperationContractExpression(this, data)
+    }
+}
+
+class KtLogicalNot<Type, Diagnostic>(val arg: KtBooleanExpression<Type, Diagnostic>) : KtBooleanExpression<Type, Diagnostic> {
+    override val erroneous: Boolean
+        get() = arg.erroneous
+
+    override fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R =
+        contractDescriptionVisitor.visitLogicalNot(this, data)
+}

core/compiler.common/src/org/jetbrains/kotlin/contracts/description/KtPredicates.kt

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2010-2023 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.contracts.description
+
+open class KtIsInstancePredicate<Type, Diagnostic>(val arg: KtValueParameterReference<Type, Diagnostic>, val type: Type, val isNegated: Boolean) :
+    KtBooleanExpression<Type, Diagnostic> {
+    override val erroneous: Boolean
+        get() = arg.erroneous
+
+    override fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R =
+        contractDescriptionVisitor.visitIsInstancePredicate(this, data)
+
+    fun negated(): KtIsInstancePredicate<Type, Diagnostic> =
+        KtIsInstancePredicate(arg, type, isNegated.not())
+}
+
+class KtErroneousIsInstancePredicate<Type, Diagnostic>(
+    arg: KtValueParameterReference<Type, Diagnostic>,
+    type: Type,
+    isNegated: Boolean,
+    val diagnostic: Diagnostic
+) : KtIsInstancePredicate<Type, Diagnostic>(arg, type, isNegated) {
+    override val erroneous: Boolean
+        get() = true
+
+    override fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R =
+        contractDescriptionVisitor.visitErroneousIsInstancePredicate(this, data)
+}
+
+class KtIsNullPredicate<Type, Diagnostic>(val arg: KtValueParameterReference<Type, Diagnostic>, val isNegated: Boolean) :
+    KtBooleanExpression<Type, Diagnostic> {
+    override val erroneous: Boolean
+        get() = arg.erroneous
+
+    override fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R =
+        contractDescriptionVisitor.visitIsNullPredicate(this, data)
+
+    fun negated(): KtIsNullPredicate<Type, Diagnostic> =
+        KtIsNullPredicate(arg, isNegated.not())
+}

core/compiler.common/src/org/jetbrains/kotlin/contracts/description/KtValues.kt

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2010-2023 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.contracts.description
+
+interface KtContractDescriptionValue<Type, Diagnostic> : KtContractDescriptionElement<Type, Diagnostic> {
+    override fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R =
+        contractDescriptionVisitor.visitValue(this, data)
+}
+
+open class KtConstantReference<Type, Diagnostic>(val name: String) : KtContractDescriptionValue<Type, Diagnostic> {
+    override val erroneous: Boolean
+        get() = false
+
+    override fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R =
+        contractDescriptionVisitor.visitConstantDescriptor(this, data)
+}
+
+class KtBooleanConstantReference<Type, Diagnostic>(name: String) : KtConstantReference<Type, Diagnostic>(name),
+    KtBooleanExpression<Type, Diagnostic> {
+    override fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R =
+        contractDescriptionVisitor.visitBooleanConstantDescriptor(this, data)
+}
+
+class KtErroneousConstantReference<Type, Diagnostic>(val diagnostic: Diagnostic) : KtConstantReference<Type, Diagnostic>("ERROR") {
+    override val erroneous: Boolean
+        get() = true
+
+    override fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R =
+        contractDescriptionVisitor.visitErroneousConstantReference(this, data)
+}
+
+/*
+ * Index of value parameter of function
+ * -1 means that it is reference to extension receiver
+ */
+open class KtValueParameterReference<Type, Diagnostic>(val parameterIndex: Int, val name: String) :
+    KtContractDescriptionValue<Type, Diagnostic> {
+    init {
+        assert(parameterIndex >= -1)
+    }
+
+    override val erroneous: Boolean
+        get() = false
+
+    override fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R =
+        contractDescriptionVisitor.visitValueParameterReference(this, data)
+}
+
+class KtBooleanValueParameterReference<Type, Diagnostic>(parameterIndex: Int, name: String) : KtValueParameterReference<Type, Diagnostic>(parameterIndex, name),
+    KtBooleanExpression<Type, Diagnostic> {
+    override fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R =
+        contractDescriptionVisitor.visitBooleanValueParameterReference(this, data)
+}
+
+class KtErroneousValueParameterReference<Type, Diagnostic>(val diagnostic: Diagnostic) : KtValueParameterReference<Type, Diagnostic>(Int.MAX_VALUE, "ERROR") {
+    override val erroneous: Boolean
+        get() = true
+
+    override fun <R, D> accept(contractDescriptionVisitor: KtContractDescriptionVisitor<R, D, Type, Diagnostic>, data: D): R =
+        contractDescriptionVisitor.visitErroneousValueParameterReference(this, data)
+}

core/compiler.common/src/org/jetbrains/kotlin/contracts/description/LogicOperationKind.kt

@@ -1,10 +1,10 @@
 /*
- * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2023 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.fir.expressions
+package org.jetbrains.kotlin.contracts.description
 
 enum class LogicOperationKind(val token: String) {
     AND("&&"), OR("||")
-}
+}

core/deserialization.common/src/org/jetbrains/kotlin/serialization/deserialization/ProtoBufContractDeserializer.kt

@@ -0,0 +1,196 @@
+/*
+ * Copyright 2010-2023 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.serialization.deserialization
+
+import org.jetbrains.kotlin.contracts.description.*
+import org.jetbrains.kotlin.contracts.description.LogicOperationKind
+import org.jetbrains.kotlin.metadata.ProtoBuf
+import org.jetbrains.kotlin.metadata.deserialization.Flags
+import org.jetbrains.kotlin.utils.addIfNotNull
+
+abstract class ProtoBufContractDeserializer<Type, Diagnostic, Owner> {
+    protected fun loadPossiblyConditionalEffect(
+        proto: ProtoBuf.Effect,
+        owner: Owner
+    ): KtEffectDeclaration<Type, Diagnostic>? {
+        if (proto.hasConclusionOfConditionalEffect()) {
+            val conclusion = loadExpression(proto.conclusionOfConditionalEffect, owner) ?: return null
+            val effect = loadSimpleEffect(proto, owner) ?: return null
+            return KtConditionalEffectDeclaration(effect, conclusion)
+        }
+        return loadSimpleEffect(proto, owner)
+    }
+
+    private fun loadSimpleEffect(proto: ProtoBuf.Effect, owner: Owner): KtEffectDeclaration<Type, Diagnostic>? {
+        val type: ProtoBuf.Effect.EffectType = if (proto.hasEffectType()) proto.effectType else return null
+        return when(type) {
+            ProtoBuf.Effect.EffectType.RETURNS_CONSTANT -> {
+                val argument = proto.effectConstructorArgumentList.firstOrNull()
+                val returnValue = if (argument == null) {
+                    getWildcard()
+                } else {
+                    @Suppress("UNCHECKED_CAST")
+                    loadExpression(argument, owner) as? KtConstantReference<Type, Diagnostic> ?: return null
+                }
+                KtReturnsEffectDeclaration(returnValue)
+            }
+            ProtoBuf.Effect.EffectType.RETURNS_NOT_NULL -> {
+                KtReturnsEffectDeclaration(getNotNull())
+            }
+            ProtoBuf.Effect.EffectType.CALLS -> {
+                val argument = proto.effectConstructorArgumentList.firstOrNull() ?: return null
+                val callable = extractVariable(argument, owner) ?: return null
+                val invocationKind = if (proto.hasKind())
+                    proto.kind.toDescriptorInvocationKind()
+                else
+                    EventOccurrencesRange.UNKNOWN
+                KtCallsEffectDeclaration(callable, invocationKind)
+            }
+        }
+    }
+
+    private fun loadExpression(proto: ProtoBuf.Expression, owner: Owner): KtBooleanExpression<Type, Diagnostic>? {
+        val primitiveType = getPrimitiveType(proto)
+        val primitiveExpression = extractPrimitiveExpression(proto, primitiveType, owner)
+
+        val complexType = getComplexType(proto)
+        val childs: MutableList<KtBooleanExpression<Type, Diagnostic>> = mutableListOf()
+        childs.addIfNotNull(primitiveExpression)
+
+        return when (complexType) {
+            ComplexExpressionType.AND_SEQUENCE -> {
+                proto.andArgumentList.mapTo(childs) { loadExpression(it, owner) ?: return null }
+                childs.reduce { acc, booleanExpression -> KtBinaryLogicExpression(acc, booleanExpression, LogicOperationKind.AND) }
+            }
+
+            ComplexExpressionType.OR_SEQUENCE -> {
+                proto.orArgumentList.mapTo(childs) { loadExpression(it, owner) ?: return null }
+                childs.reduce { acc, booleanExpression -> KtBinaryLogicExpression(acc, booleanExpression, LogicOperationKind.OR) }
+            }
+
+            null -> primitiveExpression
+        }
+    }
+
+    private fun extractPrimitiveExpression(proto: ProtoBuf.Expression, primitiveType: PrimitiveExpressionType?, owner: Owner): KtBooleanExpression<Type, Diagnostic>? {
+        val isInverted = Flags.IS_NEGATED.get(proto.flags)
+
+        return when (primitiveType) {
+            PrimitiveExpressionType.VALUE_PARAMETER_REFERENCE, PrimitiveExpressionType.RECEIVER_REFERENCE -> {
+                (extractVariable(proto, owner) as? KtBooleanValueParameterReference<Type, Diagnostic>?)?.invertIfNecessary(isInverted)
+            }
+
+            PrimitiveExpressionType.CONSTANT ->
+                (loadConstant(proto.constantValue) as? KtBooleanConstantReference<Type, Diagnostic>)?.invertIfNecessary(isInverted)
+
+            PrimitiveExpressionType.INSTANCE_CHECK -> {
+                val variable = extractVariable(proto, owner) ?: return null
+                val type = extractType(proto) ?: return null
+                KtIsInstancePredicate(variable, type, isInverted)
+            }
+
+            PrimitiveExpressionType.NULLABILITY_CHECK -> {
+                val variable = extractVariable(proto, owner) ?: return null
+                KtIsNullPredicate(variable, isInverted)
+            }
+
+            null -> null
+        }
+    }
+
+    private fun KtBooleanExpression<Type, Diagnostic>.invertIfNecessary(shouldInvert: Boolean): KtBooleanExpression<Type, Diagnostic> =
+        if (shouldInvert) KtLogicalNot(this) else this
+
+    private fun extractVariable(proto: ProtoBuf.Expression, owner: Owner): KtValueParameterReference<Type, Diagnostic>? {
+        if (!proto.hasValueParameterReference()) return null
+
+        return extractVariable(proto.valueParameterReference - 1, owner)
+    }
+
+    private fun ProtoBuf.Effect.InvocationKind.toDescriptorInvocationKind(): EventOccurrencesRange = when (this) {
+        ProtoBuf.Effect.InvocationKind.AT_MOST_ONCE -> EventOccurrencesRange.AT_MOST_ONCE
+        ProtoBuf.Effect.InvocationKind.EXACTLY_ONCE -> EventOccurrencesRange.EXACTLY_ONCE
+        ProtoBuf.Effect.InvocationKind.AT_LEAST_ONCE -> EventOccurrencesRange.AT_LEAST_ONCE
+    }
+
+    abstract fun extractVariable(valueParameterIndex: Int, owner: Owner): KtValueParameterReference<Type, Diagnostic>?
+
+    abstract fun extractType(proto: ProtoBuf.Expression): Type?
+
+    abstract fun loadConstant(value: ProtoBuf.Expression.ConstantValue): KtConstantReference<Type, Diagnostic>
+
+
+    abstract fun getNotNull(): KtConstantReference<Type, Diagnostic> 
+
+    abstract fun getWildcard(): KtConstantReference<Type, Diagnostic>
+
+
+    private fun getComplexType(proto: ProtoBuf.Expression): ComplexExpressionType? {
+        val isOrSequence = proto.orArgumentCount != 0
+        val isAndSequence = proto.andArgumentCount != 0
+        return when {
+            isOrSequence && isAndSequence -> null
+            isOrSequence -> ComplexExpressionType.OR_SEQUENCE
+            isAndSequence -> ComplexExpressionType.AND_SEQUENCE
+            else -> null
+        }
+    }
+
+    private fun getPrimitiveType(proto: ProtoBuf.Expression): PrimitiveExpressionType? {
+        // Expected to be one element, but can be empty (unknown expression) or contain several elements (invalid data)
+        val expressionTypes: MutableList<PrimitiveExpressionType> = mutableListOf()
+
+        // Check for predicates
+        when {
+            proto.hasValueParameterReference() && proto.hasType() ->
+                expressionTypes.add(PrimitiveExpressionType.INSTANCE_CHECK)
+
+            proto.hasValueParameterReference() && Flags.IS_NULL_CHECK_PREDICATE.get(proto.flags) ->
+                expressionTypes.add(PrimitiveExpressionType.NULLABILITY_CHECK)
+        }
+
+        // If message contains correct predicate, then predicate's type overrides type of value,
+        // even is message has one
+        if (expressionTypes.isNotEmpty()) {
+            return expressionTypes.singleOrNull() 
+        }
+
+        // Otherwise, check if it is a value
+        when {
+            proto.hasValueParameterReference() && proto.valueParameterReference > 0 ->
+                expressionTypes.add(PrimitiveExpressionType.VALUE_PARAMETER_REFERENCE)
+
+            proto.hasValueParameterReference() && proto.valueParameterReference == 0 ->
+                expressionTypes.add(PrimitiveExpressionType.RECEIVER_REFERENCE)
+
+            proto.hasConstantValue() -> expressionTypes.add(PrimitiveExpressionType.CONSTANT)
+        }
+
+        return expressionTypes.singleOrNull()
+    }
+
+    private fun ProtoBuf.Expression.hasType(): Boolean = this.hasIsInstanceType() || this.hasIsInstanceTypeId()
+
+    // Arguments of expressions with such types are never other expressions
+    private enum class PrimitiveExpressionType {
+        VALUE_PARAMETER_REFERENCE,
+        RECEIVER_REFERENCE,
+        CONSTANT,
+        INSTANCE_CHECK,
+        NULLABILITY_CHECK
+    }
+
+    // Expressions with such type can take other expressions as arguments.
+    // Additionally, for performance reasons, "complex expression" and "primitive expression"
+    // can co-exist in the one and the same message. If "primitive expression" is present
+    // in the current message, it is treated as the first argument of "complex expression".
+    private enum class ComplexExpressionType {
+        AND_SEQUENCE,
+        OR_SEQUENCE
+
+    }
+
+}