[FIR] Implement RECURSIVE_TYPEALIAS_EXPANSION, CYCLIC_INHERITANCE_HIERARCHY diagnostics, fix stackoverlow exception in case if typealias points to type with type arguments

compiler/fir/analysis-tests/testData/resolve/fakeRecursiveSupertype.fir.txt

@@ -5,7 +5,7 @@ FILE: fakeRecursiveSupertype.kt
         }
 
     }
-    public open class Your : R|His| {
+    public open class Your : <ERROR TYPE REF: Loop in supertype: /Your -> /His> {
         public constructor(): R|Your| {
             super<R|His|>()
         }

compiler/fir/analysis-tests/testData/resolve/fakeRecursiveSupertype.kt

@@ -1,7 +1,7 @@
 import incorrect.directory.My
 
-open class My : <!OTHER_ERROR!>My<!>()
+open class My : <!CYCLIC_INHERITANCE_HIERARCHY!>My<!>()
 
-open class Your : His()
+open class Your : <!CYCLIC_INHERITANCE_HIERARCHY!>His<!>()
 
-open class His : <!OTHER_ERROR!>Your<!>()
+open class His : <!CYCLIC_INHERITANCE_HIERARCHY!>Your<!>()

compiler/fir/analysis-tests/testData/resolve/fakeRecursiveTypealias.kt

@@ -2,4 +2,4 @@ import incorrect.directory.Your
 
 typealias My = <!UNRESOLVED_REFERENCE!>incorrect.directory.My<!>
 
-typealias Your = <!OTHER_ERROR!>Your<!>
+typealias Your = <!RECURSIVE_TYPEALIAS_EXPANSION!>Your<!>

compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/KJKComplexHierarchyNestedLoop.fir.txt

@@ -1,5 +1,5 @@
 FILE: K1.kt
-    public final class K2 : R|J1| {
+    public final class K2 : <ERROR TYPE REF: Loop in supertype: /K2 -> /J1> {
         public constructor(): R|K2| {
             super<R|J1|>()
         }

compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/KJKComplexHierarchyNestedLoop.kt

@@ -1,6 +1,6 @@
 // FIR_IDE_IGNORE
 // FILE: K1.kt
-class K2: J1() {
+class K2: <!CYCLIC_INHERITANCE_HIERARCHY!>J1<!>() {
     class Q : <!UNRESOLVED_REFERENCE!>Nested<!>()
     fun bar() {
         <!UNRESOLVED_REFERENCE!>foo<!>()

compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt

@@ -134,7 +134,7 @@ object DIAGNOSTICS_LIST : DiagnosticList("FirErrors") {
         val SUPERTYPE_NOT_A_CLASS_OR_INTERFACE by error<KtElement> {
             parameter<String>("reason")
         }
-
+        val CYCLIC_INHERITANCE_HIERARCHY by error<PsiElement>()
     }
 
     val CONSTRUCTOR_PROBLEMS by object : DiagnosticGroup("Constructor problems") {
@@ -867,6 +867,7 @@ object DIAGNOSTICS_LIST : DiagnosticList("FirErrors") {
 
     val TYPE_ALIAS by object : DiagnosticGroup("Type alias") {
         val TOPLEVEL_TYPEALIASES_ONLY by error<KtTypeAlias>()
+        val RECURSIVE_TYPEALIAS_EXPANSION by error<KtTypeAlias>()
     }
 
     val EXTENDED_CHECKERS by object : DiagnosticGroup("Extended checkers") {

compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt

@@ -143,6 +143,7 @@ object FirErrors {
     val SEALED_SUPERTYPE by error0<KtTypeReference>()
     val SEALED_SUPERTYPE_IN_LOCAL_CLASS by error0<KtTypeReference>()
     val SUPERTYPE_NOT_A_CLASS_OR_INTERFACE by error1<KtElement, String>()
+    val CYCLIC_INHERITANCE_HIERARCHY by error0<PsiElement>()
 
     // Constructor problems
     val CONSTRUCTOR_IN_OBJECT by error0<KtDeclaration>(SourceElementPositioningStrategies.DECLARATION_SIGNATURE)
@@ -481,6 +482,7 @@ object FirErrors {
 
     // Type alias
     val TOPLEVEL_TYPEALIASES_ONLY by error0<KtTypeAlias>()
+    val RECURSIVE_TYPEALIAS_EXPANSION by error0<KtTypeAlias>()
 
     // Extended checkers
     val REDUNDANT_VISIBILITY_MODIFIER by warning0<KtModifierListOwner>(SourceElementPositioningStrategies.VISIBILITY_MODIFIER)

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

@@ -5,14 +5,11 @@
 
 package org.jetbrains.kotlin.fir.analysis.checkers
 
-import org.jetbrains.kotlin.fir.analysis.checkers.type.FirSuspendModifierChecker
+import org.jetbrains.kotlin.fir.analysis.checkers.type.*
-import org.jetbrains.kotlin.fir.analysis.checkers.type.FirTypeAnnotationChecker
-import org.jetbrains.kotlin.fir.analysis.checkers.type.FirTypeRefChecker
-import org.jetbrains.kotlin.fir.analysis.checkers.type.TypeCheckers
 
 object CommonTypeCheckers : TypeCheckers() {
     override val typeRefCheckers: Set<FirTypeRefChecker> = setOf(
         FirTypeAnnotationChecker,
-        FirSuspendModifierChecker,
+        FirSuspendModifierChecker
     )
 }

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDefaultErrorMessages.kt

@@ -82,6 +82,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CONST_VAL_WITH_NO
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CREATING_AN_INSTANCE_OF_ABSTRACT_CLASS
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CYCLIC_CONSTRUCTOR_DELEGATION_CALL
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CYCLIC_GENERIC_UPPER_BOUND
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CYCLIC_INHERITANCE_HIERARCHY
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DATA_CLASS_NOT_PROPERTY_PARAMETER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DATA_CLASS_VARARG_PARAMETER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.DATA_CLASS_WITHOUT_PARAMETERS
@@ -247,6 +248,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.QUALIFIED_SUPERTY
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.RECURSION_IN_IMPLICIT_TYPES
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.RECURSION_IN_INLINE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.RECURSION_IN_SUPERTYPES
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.RECURSIVE_TYPEALIAS_EXPANSION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDECLARATION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDUNDANT_ANNOTATION_TARGET
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.REDUNDANT_CALL_OF_CONVERSION_METHOD
@@ -438,7 +440,7 @@ class FirDefaultErrorMessages : DefaultErrorMessages.Extension {
             map.put(SEALED_SUPERTYPE, "This type is sealed, so it can be inherited by only its own nested classes or objects")
             map.put(SEALED_SUPERTYPE_IN_LOCAL_CLASS, "Local class cannot extend a sealed class")
             map.put(SUPERTYPE_NOT_A_CLASS_OR_INTERFACE, "Supertype is not a class or interface", TO_STRING)
-
+            map.put(CYCLIC_INHERITANCE_HIERARCHY, "There's a cycle in the inheritance hierarchy for this type")
 
             // Constructor problems
             map.put(CONSTRUCTOR_IN_OBJECT, "Constructors are not allowed for objects")
@@ -1109,6 +1111,7 @@ class FirDefaultErrorMessages : DefaultErrorMessages.Extension {
 
             // Type alias
             map.put(TOPLEVEL_TYPEALIASES_ONLY, "Nested and local type aliases are not supported")
+            map.put(RECURSIVE_TYPEALIAS_EXPANSION, "Recursive type alias in expansion")
 
             // Returns
             map.put(RETURN_NOT_ALLOWED, "'return' is not allowed here")

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/coneDiagnosticToFirDiagnostic.kt

@@ -62,7 +62,7 @@ private fun ConeDiagnostic.toFirDiagnostic(
         FirErrors.NO_TYPE_ARGUMENTS_ON_RHS.on(qualifiedAccessSource ?: source, this.desiredCount, this.type)
     is ConeSimpleDiagnostic -> when (source.kind) {
         is FirFakeSourceElementKind -> null
-        else -> this.getFactory(source).on(qualifiedAccessSource ?: source)
+        else -> this.getFactory(source)?.on(qualifiedAccessSource ?: source)
     }
     is ConeInstanceAccessBeforeSuperCall -> FirErrors.INSTANCE_ACCESS_BEFORE_SUPER_CALL.on(source, this.target)
     is ConeStubDiagnostic -> null
@@ -277,7 +277,7 @@ private fun ConstraintSystemError.toDiagnostic(
 private val NewConstraintError.lowerConeType: ConeKotlinType get() = lowerType as ConeKotlinType
 private val NewConstraintError.upperConeType: ConeKotlinType get() = upperType as ConeKotlinType
 
-private fun ConeSimpleDiagnostic.getFactory(source: FirSourceElement): FirDiagnosticFactory0<*> {
+private fun ConeSimpleDiagnostic.getFactory(source: FirSourceElement): FirDiagnosticFactory0<*>? {
     @Suppress("UNCHECKED_CAST")
     return when (kind) {
         DiagnosticKind.Syntax -> FirErrors.SYNTAX
@@ -309,11 +309,15 @@ private fun ConeSimpleDiagnostic.getFactory(source: FirSourceElement): FirDiagno
         DiagnosticKind.IntLiteralOutOfRange -> FirErrors.INT_LITERAL_OUT_OF_RANGE
         DiagnosticKind.FloatLiteralOutOfRange -> FirErrors.FLOAT_LITERAL_OUT_OF_RANGE
         DiagnosticKind.WrongLongSuffix -> FirErrors.WRONG_LONG_SUFFIX
-        DiagnosticKind.Other -> FirErrors.OTHER_ERROR
         DiagnosticKind.IncorrectCharacterLiteral -> FirErrors.INCORRECT_CHARACTER_LITERAL
         DiagnosticKind.EmptyCharacterLiteral -> FirErrors.EMPTY_CHARACTER_LITERAL
         DiagnosticKind.TooManyCharactersInCharacterLiteral -> FirErrors.TOO_MANY_CHARACTERS_IN_CHARACTER_LITERAL
         DiagnosticKind.IllegalEscape -> FirErrors.ILLEGAL_ESCAPE
+        DiagnosticKind.RecursiveTypealiasExpansion -> FirErrors.RECURSIVE_TYPEALIAS_EXPANSION
+        DiagnosticKind.LoopInSupertype -> FirErrors.CYCLIC_INHERITANCE_HIERARCHY
+        DiagnosticKind.UnresolvedSupertype,
+        DiagnosticKind.UnresolvedExpandedType,
+        DiagnosticKind.Other -> FirErrors.OTHER_ERROR
         else -> throw IllegalArgumentException("Unsupported diagnostic kind: $kind at $javaClass")
     }
 }

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

@@ -11,6 +11,7 @@ import kotlinx.collections.immutable.toPersistentList
 import org.jetbrains.kotlin.fir.*
 import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.diagnostics.ConeSimpleDiagnostic
+import org.jetbrains.kotlin.fir.diagnostics.DiagnosticKind
 import org.jetbrains.kotlin.fir.expressions.FirStatement
 import org.jetbrains.kotlin.fir.extensions.extensionService
 import org.jetbrains.kotlin.fir.extensions.predicateBasedProvider
@@ -27,13 +28,16 @@ import org.jetbrains.kotlin.fir.scopes.impl.FirMemberTypeParameterScope
 import org.jetbrains.kotlin.fir.scopes.impl.nestedClassifierScope
 import org.jetbrains.kotlin.fir.scopes.impl.wrapNestedClassifierScopeWithSubstitutionForSuperType
 import org.jetbrains.kotlin.fir.symbols.impl.FirClassLikeSymbol
+import org.jetbrains.kotlin.fir.symbols.impl.FirRegularClassSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirTypeAliasSymbol
 import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.fir.types.builder.buildErrorTypeRef
-import org.jetbrains.kotlin.fir.visitors.*
+import org.jetbrains.kotlin.fir.visitors.FirDefaultTransformer
+import org.jetbrains.kotlin.fir.visitors.FirDefaultVisitor
+import org.jetbrains.kotlin.fir.visitors.FirTransformer
 import org.jetbrains.kotlin.name.ClassId
+import org.jetbrains.kotlin.types.model.TypeArgumentMarker
 import org.jetbrains.kotlin.utils.addIfNotNull
-import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
 class FirSupertypeResolverProcessor(session: FirSession, scopeSession: ScopeSession) :
     FirTransformerBasedResolveProcessor(session, scopeSession) {
@@ -273,7 +277,11 @@ class FirSupertypeResolverVisitor(
         when (val status = supertypeComputationSession.getSupertypesComputationStatus(classLikeDeclaration)) {
             is SupertypeComputationStatus.Computed -> return status.supertypeRefs
             is SupertypeComputationStatus.Computing -> return listOf(
-                createErrorTypeRef(classLikeDeclaration, "Loop in supertype definition for ${classLikeDeclaration.symbol.classId}")
+                createErrorTypeRef(
+                    classLikeDeclaration,
+                    "Loop in supertype definition for ${classLikeDeclaration.symbol.classId}",
+                    if (classLikeDeclaration is FirTypeAlias) DiagnosticKind.RecursiveTypealiasExpansion else DiagnosticKind.LoopInSupertype
+                )
             )
         }
 
@@ -326,7 +334,11 @@ class FirSupertypeResolverVisitor(
                             diagnostic = ConeTypeParameterSupertype(typeParameterType.lookupTag.typeParameterSymbol)
                         }
                     superTypeRef !is FirResolvedTypeRef ->
-                        createErrorTypeRef(superTypeRef, "Unresolved super-type: ${superTypeRef.render()}")
+                        createErrorTypeRef(
+                            superTypeRef,
+                            "Unresolved super-type: ${superTypeRef.render()}",
+                            DiagnosticKind.UnresolvedSupertype
+                        )
                     else ->
                         superTypeRef
                 }
@@ -360,18 +372,26 @@ class FirSupertypeResolverVisitor(
                     ?: return@resolveSpecificClassLikeSupertypes listOf(
                         createErrorTypeRef(
                             typeAlias.expandedTypeRef,
-                            "Unresolved expanded typeRef for ${typeAlias.symbol.classId}"
+                            "Unresolved expanded typeRef for ${typeAlias.symbol.classId}",
+                            DiagnosticKind.UnresolvedExpandedType
                         )
                     )
 
-            val type = resolvedTypeRef.type
+            fun visitNestedTypeAliases(type: TypeArgumentMarker) {
-            if (type is ConeClassLikeType) {
+                if (type is ConeClassLikeType) {
-                val expansionTypeAlias = type.lookupTag.toSymbol(session)?.safeAs<FirTypeAliasSymbol>()?.fir
+                    val symbol = type.lookupTag.toSymbol(session)
-                if (expansionTypeAlias != null) {
+                    if (symbol is FirTypeAliasSymbol) {
-                    visitTypeAlias(expansionTypeAlias, null)
+                        visitTypeAlias(symbol.fir, null)
+                    } else if (symbol is FirClassLikeSymbol) {
+                        for (typeArgument in type.typeArguments) {
+                            visitNestedTypeAliases(typeArgument)
+                        }
+                    }
                 }
             }
 
+            visitNestedTypeAliases(resolvedTypeRef.type)
+
             listOf(resolvedTypeRef)
         }
     }
@@ -381,9 +401,9 @@ class FirSupertypeResolverVisitor(
     }
 }
 
-private fun createErrorTypeRef(fir: FirElement, message: String) = buildErrorTypeRef {
+private fun createErrorTypeRef(fir: FirElement, message: String, kind: DiagnosticKind) = buildErrorTypeRef {
     source = fir.source
-    diagnostic = ConeSimpleDiagnostic(message)
+    diagnostic = ConeSimpleDiagnostic(message, kind)
 }
 
 class SupertypeComputationSession {
@@ -434,51 +454,95 @@ class SupertypeComputationSession {
     }
 
     private val newClassifiersForBreakingLoops = mutableListOf<FirClassLikeDeclaration<*>>()
-    private val breakLoopsDfsVisited = hashSetOf<FirClassLikeDeclaration<*>>()
 
     fun breakLoops(session: FirSession) {
-        val inProcess = hashSetOf<FirClassLikeDeclaration<*>>()
+        val visitedClassLikeDecls = mutableSetOf<FirClassLikeDeclaration<*>>()
+        val loopedClassLikeDecls = mutableSetOf<FirClassLikeDeclaration<*>>()
+        val path = mutableListOf<FirClassLikeDeclaration<*>>()
+        val pathSet = mutableSetOf<FirClassLikeDeclaration<*>>()
 
-        fun dfs(classLikeDeclaration: FirClassLikeDeclaration<*>) {
+        fun checkIsInLoop(classLikeDecl: FirClassLikeDeclaration<*>?) {
-            if (classLikeDeclaration in breakLoopsDfsVisited) return
+            if (classLikeDecl == null) return
-            val supertypeComputationStatus = supertypeStatusMap[classLikeDeclaration] ?: return
-            if (classLikeDeclaration in inProcess) return
 
-            inProcess.add(classLikeDeclaration)
+            val supertypeRefs: List<FirResolvedTypeRef>
-
+            val supertypeComputationStatus = supertypeStatusMap[classLikeDecl]
-            require(supertypeComputationStatus is SupertypeComputationStatus.Computed) {
+            supertypeRefs = if (supertypeComputationStatus != null) {
-                "Expected computed supertypes in breakLoops for ${classLikeDeclaration.symbol.classId}"
+                require(supertypeComputationStatus is SupertypeComputationStatus.Computed) {
+                    "Expected computed supertypes in breakLoops for ${classLikeDecl.symbol.classId}"
+                }
+                supertypeComputationStatus.supertypeRefs
+            } else {
+                when (classLikeDecl) {
+                    is FirRegularClass ->
+                        classLikeDecl.superTypeRefs.filterIsInstance<FirResolvedTypeRef>()
+                    is FirTypeAlias ->
+                        (classLikeDecl.expandedTypeRef as? FirResolvedTypeRef)?.let { listOf(it) } ?: listOf()
+                    else -> return
+                }
             }
 
-            val typeRefs = supertypeComputationStatus.supertypeRefs
+            if (classLikeDecl in visitedClassLikeDecls) {
-            val resultingTypeRefs = mutableListOf<FirResolvedTypeRef>()
+                if (classLikeDecl in pathSet) {
-            var wereChanges = false
+                    loopedClassLikeDecls.add(classLikeDecl)
+                    loopedClassLikeDecls.addAll(path.takeLastWhile { element -> element != classLikeDecl })
+                }
+                return
+            }
 
-            for (typeRef in typeRefs) {
+            path.add(classLikeDecl)
-                val fir = typeRef.firClassLike(session)
+            pathSet.add(classLikeDecl)
-                fir?.let(::dfs)
+            visitedClassLikeDecls.add(classLikeDecl)
-                resultingTypeRefs.add(
+
-                    if (fir in inProcess) {
+            val parentId = classLikeDecl.symbol.classId.relativeClassName.parent()
-                        wereChanges = true
+            if (!parentId.isRoot) {
+                val parentSymbol = session.symbolProvider.getClassLikeSymbolByFqName(ClassId.fromString(parentId.asString()))
+                if (parentSymbol is FirRegularClassSymbol) {
+                    checkIsInLoop(parentSymbol.fir)
+                }
+            }
+
+            val isTypeAlias = classLikeDecl is FirTypeAlias
+            var isErrorInSupertypesFound = false
+            val resultSupertypeRefs = mutableListOf<FirResolvedTypeRef>()
+            for (supertypeRef in supertypeRefs) {
+                val supertypeFir = supertypeRef.firClassLike(session)
+                checkIsInLoop(supertypeFir)
+
+                if (isTypeAlias) {
+                    for (typeArgument in supertypeRef.type.typeArguments) {
+                        if (typeArgument is ConeClassLikeType) {
+                            checkIsInLoop(typeArgument.lookupTag.toSymbol(session)?.fir)
+                        }
+                    }
+                }
+
+                resultSupertypeRefs.add(
+                    if (classLikeDecl in loopedClassLikeDecls) {
+                        isErrorInSupertypesFound = true
                         createErrorTypeRef(
-                            typeRef,
+                            supertypeRef,
-                            "Loop in supertype: ${classLikeDeclaration.symbol.classId} -> ${fir?.symbol?.classId}"
+                            "Loop in supertype: ${classLikeDecl.symbol.classId} -> ${supertypeFir?.symbol?.classId}",
+                            if (isTypeAlias) DiagnosticKind.RecursiveTypealiasExpansion else DiagnosticKind.LoopInSupertype
                         )
-                    } else
+                    } else {
-                        typeRef
+                        supertypeRef
+                    }
                 )
             }
 
-            if (wereChanges) {
+            if (isErrorInSupertypesFound) {
-                supertypeStatusMap[classLikeDeclaration] = SupertypeComputationStatus.Computed(resultingTypeRefs)
+                supertypeStatusMap[classLikeDecl] = SupertypeComputationStatus.Computed(resultSupertypeRefs)
             }
 
-            inProcess.remove(classLikeDeclaration)
+            path.removeAt(path.size - 1)
-            breakLoopsDfsVisited.add(classLikeDeclaration)
+            pathSet.remove(classLikeDecl)
         }
 
         for (classifier in newClassifiersForBreakingLoops) {
-            dfs(classifier)
+            checkIsInLoop(classifier)
+            require(path.isEmpty()) {
+                "Path should be empty"
+            }
         }
         newClassifiersForBreakingLoops.clear()
     }

compiler/fir/tree/src/org/jetbrains/kotlin/fir/diagnostics/ConeSimpleDiagnostic.kt

@@ -36,6 +36,11 @@ enum class DiagnosticKind {
     IllegalProjectionUsage,
     MissingStdlibClass,
 
+    LoopInSupertype,
+    RecursiveTypealiasExpansion,
+    UnresolvedSupertype,
+    UnresolvedExpandedType,
+
     IncorrectCharacterLiteral,
     EmptyCharacterLiteral,
     TooManyCharactersInCharacterLiteral,

compiler/testData/diagnostics/tests/cast/IsRecursionSustainable.fir.kt

@@ -1,6 +1,6 @@
-open class RecA<T>: RecB<T>()
+open class RecA<T>: <!CYCLIC_INHERITANCE_HIERARCHY!>RecB<T><!>()
-open class RecB<T>: <!OTHER_ERROR!>RecA<T><!>()
+open class RecB<T>: <!CYCLIC_INHERITANCE_HIERARCHY!>RecA<T><!>()
-open class SelfR<T>: <!OTHER_ERROR!>SelfR<T><!>()
+open class SelfR<T>: <!CYCLIC_INHERITANCE_HIERARCHY!>SelfR<T><!>()
 
 fun test(f: SelfR<String>) = f is RecA<String>
-fun test(f: RecB<String>) = f is RecA<String>
+fun test(f: RecB<String>) = f is RecA<String>

compiler/testData/diagnostics/tests/cyclicHierarchy/classIndirectlyInheritsNested.fir.kt

@@ -1,4 +0,0 @@
-open class C : D() {
-    open class CC
-}
-open class D : C.CC()

compiler/testData/diagnostics/tests/cyclicHierarchy/classIndirectlyInheritsNested.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 open class C : <!CYCLIC_INHERITANCE_HIERARCHY!>D<!>() {
     open class CC
 }

compiler/testData/diagnostics/tests/cyclicHierarchy/classInheritsNested.fir.kt

@@ -1,3 +0,0 @@
-open class E : E.EE() {
-    open class EE
-}

compiler/testData/diagnostics/tests/cyclicHierarchy/classInheritsNested.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 open class E : <!CYCLIC_INHERITANCE_HIERARCHY!>E.EE<!>() {
     open class EE
 }

compiler/testData/diagnostics/tests/cyclicHierarchy/commonSupertypeForCyclicAndUsualTypes.fir.kt

@@ -1,8 +0,0 @@
-open class A : B()
-open class B : <!OTHER_ERROR!>A<!>()
-
-fun <T> select(vararg xs: T): T = xs[0]
-
-fun foo() {
-    val x = select(A(), B(), "foo")
-}

compiler/testData/diagnostics/tests/cyclicHierarchy/commonSupertypeForCyclicAndUsualTypes.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 open class A : <!CYCLIC_INHERITANCE_HIERARCHY!>B<!>()
 open class B : <!CYCLIC_INHERITANCE_HIERARCHY!>A<!>()
 

compiler/testData/diagnostics/tests/cyclicHierarchy/commonSupertypeForCyclicTypes.fir.kt

@@ -1,8 +0,0 @@
-open class A : B()
-open class B : <!OTHER_ERROR!>A<!>()
-
-fun <T> select(vararg xs: T): T = xs[0]
-
-fun foo() {
-    select(A(), B())
-}

compiler/testData/diagnostics/tests/cyclicHierarchy/commonSupertypeForCyclicTypes.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 open class A : <!CYCLIC_INHERITANCE_HIERARCHY!>B<!>()
 open class B : <!CYCLIC_INHERITANCE_HIERARCHY!>A<!>()
 

compiler/testData/diagnostics/tests/cyclicHierarchy/cyclicHierarchy.fir.kt

@@ -1,30 +0,0 @@
-interface A {
-    fun foo() {}
-}
-interface B : A, E {}
-interface C : <!OTHER_ERROR!>B<!> {}
-interface D : <!OTHER_ERROR!>B<!> {}
-interface E : F {}
-interface F : D, C {}
-interface G : F {}
-interface H : F {}
-
-val a : A? = null
-val b : B? = null
-val c : C? = null
-val d : D? = null
-val e : E? = null
-val f : F? = null
-val g : G? = null
-val h : H? = null
-
-fun test() {
-    a?.foo()
-    b?.foo()
-    c?.<!UNRESOLVED_REFERENCE!>foo<!>()
-    d?.<!UNRESOLVED_REFERENCE!>foo<!>()
-    e?.<!UNRESOLVED_REFERENCE!>foo<!>()
-    f?.<!UNRESOLVED_REFERENCE!>foo<!>()
-    g?.<!UNRESOLVED_REFERENCE!>foo<!>()
-    h?.<!UNRESOLVED_REFERENCE!>foo<!>()
-}

compiler/testData/diagnostics/tests/cyclicHierarchy/cyclicHierarchy.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 interface A {
     fun foo() {}
 }

compiler/testData/diagnostics/tests/cyclicHierarchy/javaKotlinJavaCycle.fir.kt

@@ -1,17 +0,0 @@
-// FILE: A.java
-
-interface A extends C {
-    void foo();
-}
-
-// FILE: B.kt
-
-interface B : <!EXPOSED_SUPER_INTERFACE!>A<!> {
-    fun bar()
-}
-
-// FILE: C.java
-
-interface C extends B {
-    void baz();
-}

compiler/testData/diagnostics/tests/cyclicHierarchy/javaKotlinJavaCycle.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // FILE: A.java
 
 interface A extends C {

compiler/testData/diagnostics/tests/cyclicHierarchy/kotlinJavaCycle.fir.kt

@@ -1,11 +0,0 @@
-// FILE: J.java
-
-class J extends K {
-    void foo() {}
-}
-
-// FILE: K.kt
-
-class K : <!EXPOSED_SUPER_CLASS!>J<!>() {
-    fun bar() {}
-}

compiler/testData/diagnostics/tests/cyclicHierarchy/kotlinJavaCycle.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // FILE: J.java
 
 class J extends K {

compiler/testData/diagnostics/tests/cyclicHierarchy/kotlinJavaKotlinCycle.fir.kt

@@ -12,6 +12,6 @@ class J extends I {
 
 // FILE: K.kt
 
-open class K : <!EXPOSED_SUPER_CLASS!>J<!>() {
+open class K : <!CYCLIC_INHERITANCE_HIERARCHY!>J<!>() {
     fun baz() {}
 }

compiler/testData/diagnostics/tests/cyclicHierarchy/kotlinJavaNestedCycle.fir.kt

@@ -5,7 +5,7 @@ interface ExceptionTracker : <!EXPOSED_SUPER_INTERFACE!>LockBasedStorageManager.
 
 // FILE: StorageManager.kt
 
-interface StorageManager : ExceptionTracker {
+interface StorageManager : <!CYCLIC_INHERITANCE_HIERARCHY!>ExceptionTracker<!> {
     fun foo()
 }
 

compiler/testData/diagnostics/tests/cyclicHierarchy/kt303.fir.kt

@@ -1,10 +1,10 @@
 // KT-303 Stack overflow on a cyclic class hierarchy
 
-open class Foo() : Bar() {
+open class Foo() : <!CYCLIC_INHERITANCE_HIERARCHY!>Bar<!>() {
   val a : Int = 1
 }
 
-open class Bar() : <!OTHER_ERROR!>Foo<!>() {
+open class Bar() : <!CYCLIC_INHERITANCE_HIERARCHY!>Foo<!>() {
 
 }
 

compiler/testData/diagnostics/tests/cyclicHierarchy/objectInheritsNested.fir.kt

@@ -1,22 +0,0 @@
-// As in KT-18514
-object A : A.I {
-    interface I
-}
-
-// Similar to 'classIndirectlyInheritsNested.kt'
-object D : E() {
-    open class NestedD
-}
-
-open class E : D.NestedD()
-
-
-
-// Similar to 'twoClassesWithNestedCycle.kt'
-object G : H.NestedH() {
-    open class NestedG
-}
-object H : G.NestedG() {
-    open class NestedH
-}
-

compiler/testData/diagnostics/tests/cyclicHierarchy/objectInheritsNested.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // As in KT-18514
 object A : <!CYCLIC_INHERITANCE_HIERARCHY!>A.I<!> {
     interface I

compiler/testData/diagnostics/tests/cyclicHierarchy/twoClassesWithNestedCycle.fir.kt

@@ -1,6 +0,0 @@
-open class A : B.BB() {
-    open class AA
-}
-open class B : A.AA() {
-    open class BB
-}

compiler/testData/diagnostics/tests/cyclicHierarchy/twoClassesWithNestedCycle.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 open class A : <!CYCLIC_INHERITANCE_HIERARCHY!>B.BB<!>() {
     open class AA
 }

compiler/testData/diagnostics/tests/resolve/dslMarker/dslMarkerWithTypealiasRecursion.fir.kt

@@ -8,8 +8,8 @@ class Foo
 
 class Bar
 
-typealias YBar = <!OTHER_ERROR!>ZBar<!>
+typealias YBar = <!RECURSIVE_TYPEALIAS_EXPANSION!>ZBar<!>
-typealias ZBar = YBar
+typealias ZBar = <!RECURSIVE_TYPEALIAS_EXPANSION!>YBar<!>
 
 fun Foo.foo(body: Foo.() -> Unit) = body()
 fun Foo.zbar(body: ZBar.() -> Unit) = Bar().body()

compiler/testData/diagnostics/tests/scopes/classHeader/companionObjectParents.fir.kt

@@ -7,7 +7,7 @@ val bImpl: B.Companion.Interface
     get() = null!!
 
 interface A {
-    companion object : <!FINAL_SUPERTYPE!>Nested<!>(), Interface by aImpl, I<Nested, Interface> {
+    companion object : <!CYCLIC_INHERITANCE_HIERARCHY!>Nested<!>(), <!CYCLIC_INHERITANCE_HIERARCHY!>Interface<!> by aImpl, <!CYCLIC_INHERITANCE_HIERARCHY!>I<Nested, Interface><!> {
 
         class Nested
 
@@ -16,7 +16,7 @@ interface A {
 }
 
 class B {
-    companion object : <!FINAL_SUPERTYPE!>Nested<!>(), Interface by aImpl, I<Nested, Interface> {
+    companion object : <!CYCLIC_INHERITANCE_HIERARCHY!>Nested<!>(), <!CYCLIC_INHERITANCE_HIERARCHY!>Interface<!> by aImpl, <!CYCLIC_INHERITANCE_HIERARCHY!>I<Nested, Interface><!> {
 
         class Nested
 

compiler/testData/diagnostics/tests/typealias/cyclicInheritanceViaTypeAlias.fir.kt

@@ -1,7 +1,7 @@
-class A : B() {
+class A : <!CYCLIC_INHERITANCE_HIERARCHY!>B<!>() {
     open class Nested<T>
 }
 
-typealias ANested<T> = A.Nested<T>
+typealias ANested<T> = <!RECURSIVE_TYPEALIAS_EXPANSION!>A.Nested<T><!>
 
-open class B : ANested<Int>()
+open class B : <!CYCLIC_INHERITANCE_HIERARCHY, UNRESOLVED_REFERENCE!>ANested<Int><!>()

compiler/testData/diagnostics/tests/typealias/recursive.fir.kt

@@ -1,11 +1,12 @@
-typealias R = <!OTHER_ERROR!>R<!>
+typealias R = <!RECURSIVE_TYPEALIAS_EXPANSION!>R<!>
 
-typealias L = List<L>
+typealias L = <!RECURSIVE_TYPEALIAS_EXPANSION!>List<L><!>
 
-typealias A = <!OTHER_ERROR!>B<!>
+typealias A = <!RECURSIVE_TYPEALIAS_EXPANSION!>B<!>
-typealias B = A
+typealias B = <!RECURSIVE_TYPEALIAS_EXPANSION!>A<!>
 
-typealias F1 = (Int) -> F2
+typealias F1 = <!RECURSIVE_TYPEALIAS_EXPANSION!>(Int) -> F2<!>
-typealias F2 = (F1) -> Int
+typealias F2 = <!RECURSIVE_TYPEALIAS_EXPANSION!>(F1) -> Int<!>
+typealias F3 = (F1) -> Int
 
-val x: A = TODO()
+val x: F3 = TODO()

compiler/testData/diagnostics/tests/typealias/recursive.kt

@@ -7,5 +7,6 @@ typealias B = <!RECURSIVE_TYPEALIAS_EXPANSION!>A<!>
 
 typealias F1 = <!RECURSIVE_TYPEALIAS_EXPANSION!>(Int) -> F2<!>
 typealias F2 = <!RECURSIVE_TYPEALIAS_EXPANSION!>(F1) -> Int<!>
+typealias F3 = <!RECURSIVE_TYPEALIAS_EXPANSION!>(F1) -> Int<!>
 
-val x: <!RECURSIVE_TYPEALIAS_EXPANSION!>A<!> = TODO()
+val x: <!RECURSIVE_TYPEALIAS_EXPANSION!>F3<!> = TODO()

compiler/testData/diagnostics/tests/typealias/recursive.txt

@@ -1,9 +1,11 @@
 package
 
-public val x: [ERROR : Recursive type alias: A]
+public val x: F3 /* = (F1 /* = (kotlin.Int) -> F2 /* = ([ERROR : Recursive type alias: F1]) -> kotlin.Int */ */) -> kotlin.Int */
 public typealias A = B
 public typealias B = A
 public typealias F1 = (kotlin.Int) -> F2
 public typealias F2 = (F1) -> kotlin.Int
+public typealias F3 = (F1) -> kotlin.Int
 public typealias L = kotlin.collections.List<L>
 public typealias R = R
+

compiler/tests-spec/testData/diagnostics/linked/declarations/classifier-declaration/class-declaration/abstract-classes/p-2/neg/1.10.fir.kt

@@ -1,51 +0,0 @@
-// !LANGUAGE: +NewInference +ProhibitInvisibleAbstractMethodsInSuperclasses
-// !DIAGNOSTICS: -UNUSED_VARIABLE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -UNUSED_PARAMETER -UNUSED_EXPRESSION
-// SKIP_TXT
-// FULL_JDK
-
-// TESTCASE NUMBER: 1
-<!ABSTRACT_CLASS_MEMBER_NOT_IMPLEMENTED!>class Case1<!>() : BaseCase1(), InterfaceCase1 {}
-
-abstract class BaseCase1() {
-    abstract fun foo(): String
-    abstract val a: String
-}
-
-interface InterfaceCase1 {
-    fun foo() = "foo"
-    val a: String
-        get() = "a"
-}
-
-// TESTCASE NUMBER: 2
-class Case2Outer {
-    val v = "v"
-
-    abstract class Case2Base() {
-        abstract fun foo(): String
-    }
-
-    inner
-    <!ABSTRACT_CLASS_MEMBER_NOT_IMPLEMENTED!>class A<!>() : Case2Base() {
-
-    }
-}
-
-// TESTCASE NUMBER: 3
-fun case3() {
-    <!ABSTRACT_CLASS_MEMBER_NOT_IMPLEMENTED!>object<!> : CaseOuter.CaseBase() {}.outerFoo()
-}
-
-<!ABSTRACT_CLASS_MEMBER_NOT_IMPLEMENTED!>class B<!>() : CaseOuter.CaseBase() {}
-
-sealed class CaseOuter {
-    val v = "v"
-    abstract fun outerFoo();
-
-    abstract class CaseBase() : CaseOuter() {
-        abstract fun foo(): String
-    }
-
-    <!ABSTRACT_CLASS_MEMBER_NOT_IMPLEMENTED!>class A<!>() : CaseBase() {
-    }
-}

compiler/tests-spec/testData/diagnostics/linked/declarations/classifier-declaration/class-declaration/abstract-classes/p-2/neg/1.10.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // !LANGUAGE: +NewInference +ProhibitInvisibleAbstractMethodsInSuperclasses
 // !DIAGNOSTICS: -UNUSED_VARIABLE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -UNUSED_PARAMETER -UNUSED_EXPRESSION
 // SKIP_TXT

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDataClassConverters.kt

@@ -407,6 +407,12 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirErrors.CYCLIC_INHERITANCE_HIERARCHY) { firDiagnostic ->
+        CyclicInheritanceHierarchyImpl(
+            firDiagnostic as FirPsiDiagnostic<*>,
+            token,
+        )
+    }
     add(FirErrors.CONSTRUCTOR_IN_OBJECT) { firDiagnostic ->
         ConstructorInObjectImpl(
             firDiagnostic as FirPsiDiagnostic<*>,
@@ -2378,6 +2384,12 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirErrors.RECURSIVE_TYPEALIAS_EXPANSION) { firDiagnostic ->
+        RecursiveTypealiasExpansionImpl(
+            firDiagnostic as FirPsiDiagnostic<*>,
+            token,
+        )
+    }
     add(FirErrors.REDUNDANT_VISIBILITY_MODIFIER) { firDiagnostic ->
         RedundantVisibilityModifierImpl(
             firDiagnostic as FirPsiDiagnostic<*>,

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnostics.kt

@@ -303,6 +303,10 @@ sealed class KtFirDiagnostic<PSI: PsiElement> : KtDiagnosticWithPsi<PSI> {
         abstract val reason: String
     }
 
+    abstract class CyclicInheritanceHierarchy : KtFirDiagnostic<PsiElement>() {
+        override val diagnosticClass get() = CyclicInheritanceHierarchy::class
+    }
+
     abstract class ConstructorInObject : KtFirDiagnostic<KtDeclaration>() {
         override val diagnosticClass get() = ConstructorInObject::class
     }
@@ -1670,6 +1674,10 @@ sealed class KtFirDiagnostic<PSI: PsiElement> : KtDiagnosticWithPsi<PSI> {
         override val diagnosticClass get() = ToplevelTypealiasesOnly::class
     }
 
+    abstract class RecursiveTypealiasExpansion : KtFirDiagnostic<KtTypeAlias>() {
+        override val diagnosticClass get() = RecursiveTypealiasExpansion::class
+    }
+
     abstract class RedundantVisibilityModifier : KtFirDiagnostic<KtModifierListOwner>() {
         override val diagnosticClass get() = RedundantVisibilityModifier::class
     }

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnosticsImpl.kt

@@ -472,6 +472,13 @@ internal class SupertypeNotAClassOrInterfaceImpl(
     override val firDiagnostic: FirPsiDiagnostic<*> by weakRef(firDiagnostic)
 }
 
+internal class CyclicInheritanceHierarchyImpl(
+    firDiagnostic: FirPsiDiagnostic<*>,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.CyclicInheritanceHierarchy(), KtAbstractFirDiagnostic<PsiElement> {
+    override val firDiagnostic: FirPsiDiagnostic<*> by weakRef(firDiagnostic)
+}
+
 internal class ConstructorInObjectImpl(
     firDiagnostic: FirPsiDiagnostic<*>,
     override val token: ValidityToken,
@@ -2703,6 +2710,13 @@ internal class ToplevelTypealiasesOnlyImpl(
     override val firDiagnostic: FirPsiDiagnostic<*> by weakRef(firDiagnostic)
 }
 
+internal class RecursiveTypealiasExpansionImpl(
+    firDiagnostic: FirPsiDiagnostic<*>,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.RecursiveTypealiasExpansion(), KtAbstractFirDiagnostic<KtTypeAlias> {
+    override val firDiagnostic: FirPsiDiagnostic<*> by weakRef(firDiagnostic)
+}
+
 internal class RedundantVisibilityModifierImpl(
     firDiagnostic: FirPsiDiagnostic<*>,
     override val token: ValidityToken,

idea/testData/checker/CyclicHierarchy.fir.kt

@@ -1,11 +1,11 @@
 interface A {
     fun foo() {}
 }
-interface B : A, E {}
+interface B : A, <error descr="[CYCLIC_INHERITANCE_HIERARCHY] There's a cycle in the inheritance hierarchy for this type">E</error> {}
-interface C : <error descr="[OTHER_ERROR] Unknown (other) error">B</error> {}
+interface C : <error descr="[CYCLIC_INHERITANCE_HIERARCHY] There's a cycle in the inheritance hierarchy for this type">B</error> {}
-interface D : <error descr="[OTHER_ERROR] Unknown (other) error">B</error> {}
+interface D : <error descr="[CYCLIC_INHERITANCE_HIERARCHY] There's a cycle in the inheritance hierarchy for this type">B</error> {}
-interface E : F {}
+interface E : <error descr="[CYCLIC_INHERITANCE_HIERARCHY] There's a cycle in the inheritance hierarchy for this type">F</error> {}
-interface F : D, C {}
+interface F : <error descr="[CYCLIC_INHERITANCE_HIERARCHY] There's a cycle in the inheritance hierarchy for this type">D</error>, <error descr="[CYCLIC_INHERITANCE_HIERARCHY] There's a cycle in the inheritance hierarchy for this type">C</error> {}
 interface G : F {}
 interface H : F {}
 

idea/testData/checker/regression/kt303.fir.kt

@@ -1,10 +1,10 @@
 // KT-303 Stack overflow on a cyclic class hierarchy
 
-open class Foo() : Bar() {
+open class Foo() : <error descr="[CYCLIC_INHERITANCE_HIERARCHY] There's a cycle in the inheritance hierarchy for this type">Bar</error>() {
   val a : Int = 1
 }
 
-open class Bar() : <error descr="[OTHER_ERROR] Unknown (other) error">Foo</error>() {
+open class Bar() : <error descr="[CYCLIC_INHERITANCE_HIERARCHY] There's a cycle in the inheritance hierarchy for this type">Foo</error>() {
 
 }
 

idea/testData/checker/trivialHierarchyLoop.fir.kt

@@ -1,3 +1,3 @@
-class A : <error descr="[OTHER_ERROR] Unknown (other) error">A</error>() {}
+class A : <error descr="[CYCLIC_INHERITANCE_HIERARCHY] There's a cycle in the inheritance hierarchy for this type">A</error>() {}
 
 val x : Int = <error descr="[INITIALIZER_TYPE_MISMATCH] Initializer type mismatch: expected kotlin/Int, actual A"><error descr="[TYPE_MISMATCH] Type mismatch: inferred type is A but kotlin/Int was expected">A()</error></error>