[FIR2IR] Properly setup IrClass.sealedSubclasses

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

@@ -561,3 +561,11 @@ fun Fir2IrComponents.computeInlineClassRepresentation(klass: FirRegularClass): I
         underlyingType as? IrSimpleType ?: error("Inline class underlying type is not a simple type: ${klass.render()}")
     )
 }
+
+fun FirRegularClass.getIrSymbolsForSealedSubclasses(components: Fir2IrComponents): List<IrClassSymbol> {
+    val session = components.session
+    val symbolProvider = session.symbolProvider
+    return getSealedClassInheritors(session).mapNotNull {
+        symbolProvider.getClassLikeSymbolByClassId(it)?.toSymbol(session, components.classifierStorage)
+    }.filterIsInstance<IrClassSymbol>()
+}

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

@@ -15,10 +15,7 @@ import org.jetbrains.kotlin.fir.backend.generators.OperatorExpressionGenerator
 import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.declarations.builder.buildProperty
 import org.jetbrains.kotlin.fir.declarations.impl.FirDeclarationStatusImpl
-import org.jetbrains.kotlin.fir.declarations.utils.expandedConeType
-import org.jetbrains.kotlin.fir.declarations.utils.isSynthetic
-import org.jetbrains.kotlin.fir.declarations.utils.primaryConstructor
-import org.jetbrains.kotlin.fir.declarations.utils.visibility
+import org.jetbrains.kotlin.fir.declarations.utils.*
 import org.jetbrains.kotlin.fir.expressions.*
 import org.jetbrains.kotlin.fir.expressions.builder.buildBlock
 import org.jetbrains.kotlin.fir.expressions.impl.FirElseIfTrueCondition
@@ -156,6 +153,9 @@ class Fir2IrVisitor(
             converter.processLocalClassAndNestedClasses(regularClass, irParent)
         }
         val irClass = classifierStorage.getCachedIrClass(regularClass)!!
+        if (regularClass.isSealed) {
+            irClass.sealedSubclasses = regularClass.getIrSymbolsForSealedSubclasses(components)
+        }
         return conversionScope.withParent(irClass) {
             conversionScope.withContainingFirClass(regularClass) {
                 memberGenerator.convertClassContent(irClass, regularClass)

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/lazy/Fir2IrLazyClass.kt

@@ -6,10 +6,8 @@
 package org.jetbrains.kotlin.fir.lazy
 
 import org.jetbrains.kotlin.descriptors.*
-import org.jetbrains.kotlin.fir.backend.Fir2IrComponents
-import org.jetbrains.kotlin.fir.backend.computeInlineClassRepresentation
+import org.jetbrains.kotlin.fir.backend.*
 import org.jetbrains.kotlin.fir.backend.declareThisReceiverParameter
-import org.jetbrains.kotlin.fir.backend.toIrType
 import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.declarations.utils.*
 import org.jetbrains.kotlin.fir.dispatchReceiverClassOrNull
@@ -104,7 +102,11 @@ class Fir2IrLazyClass(
     }
 
     override var sealedSubclasses: List<IrClassSymbol> by lazyVar(lock) {
-        TODO()
+        if (fir.isSealed) {
+            fir.getIrSymbolsForSealedSubclasses(components)
+        } else {
+            emptyList()
+        }
     }
 
     override var thisReceiver: IrValueParameter? by lazyVar(lock) {

compiler/testData/codegen/box/smartCasts/kt44814.fir.txt

@@ -19,6 +19,9 @@ FILE fqName:<root> fileName:/kt44814.kt
         public open fun toString (): kotlin.String declared in kotlin.Any
       $this: VALUE_PARAMETER name:<this> type:kotlin.Any
   CLASS CLASS name:FirSourceElement modality:SEALED visibility:public superTypes:[kotlin.Any]
+    sealedSubclasses:
+      CLASS CLASS name:FirPsiSourceElement modality:FINAL visibility:public superTypes:[<root>.FirSourceElement]
+      CLASS CLASS name:FirLightSourceElement modality:FINAL visibility:public superTypes:[<root>.FirSourceElement]
     $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.FirSourceElement
     CONSTRUCTOR visibility:protected <> () returnType:<root>.FirSourceElement [primary]
       BLOCK_BODY
@@ -368,6 +371,9 @@ FILE fqName:<root> fileName:/kt44814.kt
         public open fun toString (): kotlin.String [fake_override] declared in <root>.PsiElement
       $this: VALUE_PARAMETER name:<this> type:kotlin.Any
   CLASS CLASS name:FirModifier modality:SEALED visibility:internal superTypes:[kotlin.Any]
+    sealedSubclasses:
+      CLASS CLASS name:FirPsiModifier modality:FINAL visibility:public superTypes:[<root>.FirModifier<<root>.ASTNode>]
+      CLASS CLASS name:FirLightModifier modality:FINAL visibility:public superTypes:[<root>.FirModifier<<root>.LighterASTNode>]
     $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.FirModifier<Node of <root>.FirModifier>
     TYPE_PARAMETER name:Node index:0 variance: superTypes:[kotlin.Any]
     CONSTRUCTOR visibility:protected <> (node:Node of <root>.FirModifier, token:<root>.KtModifierKeywordToken) returnType:<root>.FirModifier<Node of <root>.FirModifier> [primary]
@@ -504,6 +510,9 @@ FILE fqName:<root> fileName:/kt44814.kt
         public open fun toString (): kotlin.String declared in kotlin.Any
       $this: VALUE_PARAMETER name:<this> type:kotlin.Any
   CLASS CLASS name:FirModifierList modality:SEALED visibility:internal superTypes:[kotlin.Any]
+    sealedSubclasses:
+      CLASS CLASS name:FirPsiModifierList modality:FINAL visibility:public superTypes:[<root>.FirModifierList]
+      CLASS CLASS name:FirLightModifierList modality:FINAL visibility:public superTypes:[<root>.FirModifierList]
     $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.FirModifierList
     CONSTRUCTOR visibility:protected <> () returnType:<root>.FirModifierList [primary]
       BLOCK_BODY

compiler/testData/ir/irText/firProblems/ArrayMap.fir.txt

@@ -1,5 +1,9 @@
 FILE fqName:<root> fileName:/ArrayMap.kt
   CLASS CLASS name:ArrayMap modality:SEALED visibility:public superTypes:[kotlin.collections.Iterable<T of <root>.ArrayMap>]
+    sealedSubclasses:
+      CLASS OBJECT name:EmptyArrayMap modality:FINAL visibility:internal superTypes:[<root>.ArrayMap<kotlin.Nothing>]
+      CLASS CLASS name:OneElementArrayMap modality:FINAL visibility:internal superTypes:[<root>.ArrayMap<T of <root>.OneElementArrayMap>]
+      CLASS CLASS name:ArrayMapImpl modality:FINAL visibility:internal superTypes:[<root>.ArrayMap<T of <root>.ArrayMapImpl>]
     $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.ArrayMap<T of <root>.ArrayMap>
     TYPE_PARAMETER name:T index:0 variance: superTypes:[kotlin.Any]
     CONSTRUCTOR visibility:protected <> () returnType:<root>.ArrayMap<T of <root>.ArrayMap> [primary]

compiler/testData/ir/irText/regressions/kt45236.fir.txt

@@ -1,5 +1,7 @@
 FILE fqName:<root> fileName:/kt45236.kt
   CLASS CLASS name:NetRequestStatus modality:SEALED visibility:public superTypes:[kotlin.Any]
+    sealedSubclasses:
+      CLASS CLASS name:Error modality:FINAL visibility:public [data] superTypes:[<root>.NetRequestStatus<T of <root>.NetRequestStatus.Error>]
     $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.NetRequestStatus<T of <root>.NetRequestStatus>
     TYPE_PARAMETER name:T index:0 variance:out superTypes:[kotlin.Any]
     CONSTRUCTOR visibility:protected <> () returnType:<root>.NetRequestStatus<T of <root>.NetRequestStatus> [primary]