[FIR2IR] OptIn to using IrClass.declarations in all appropriate places

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrConverter.kt

@@ -31,6 +31,7 @@ import org.jetbrains.kotlin.fir.extensions.extensionService
 import org.jetbrains.kotlin.fir.extensions.generatedMembers
 import org.jetbrains.kotlin.fir.extensions.generatedNestedClassifiers
 import org.jetbrains.kotlin.fir.java.javaElementFinder
+import org.jetbrains.kotlin.fir.lazy.Fir2IrLazyClass
 import org.jetbrains.kotlin.fir.resolve.ScopeSession
 import org.jetbrains.kotlin.fir.symbols.lazyDeclarationResolver
 import org.jetbrains.kotlin.fir.types.resolvedType
@@ -48,9 +49,10 @@ import org.jetbrains.kotlin.ir.interpreter.IrInterpreterEnvironment
 import org.jetbrains.kotlin.ir.interpreter.checker.EvaluationMode
 import org.jetbrains.kotlin.ir.interpreter.transformer.transformConst
 import org.jetbrains.kotlin.ir.overrides.IrFakeOverrideBuilder
+import org.jetbrains.kotlin.ir.symbols.IrSymbolInternals
+import org.jetbrains.kotlin.ir.types.IrTypeSystemContext
 import org.jetbrains.kotlin.ir.symbols.impl.IrConstructorPublicSymbolImpl
 import org.jetbrains.kotlin.ir.symbols.impl.IrSimpleFunctionPublicSymbolImpl
-import org.jetbrains.kotlin.ir.types.IrTypeSystemContext
 import org.jetbrains.kotlin.ir.util.KotlinMangler
 import org.jetbrains.kotlin.ir.util.NaiveSourceBasedFileEntryImpl
 import org.jetbrains.kotlin.ir.util.defaultType
@@ -185,7 +187,10 @@ class Fir2IrConverter(
          * IrFile should contain declarations in the source order, but creating of IrClass automatically adds created class to the list
          *   of file declaration. And in this step we skip all callables, so by default all classes will be declared before all callables
          * To fix this issue the list of declarations is cleared at this point, and later it will be filled again in `processClassMembers`
+         *
+         * `irFile` is definitely not a lazy class
          */
+        @OptIn(IrSymbolInternals::class)
         irFile.declarations.clear()
     }
 
@@ -207,7 +212,10 @@ class Fir2IrConverter(
          * IrClass should contain declarations in the source order, but creating of nested IrClass automatically adds created class to the list
          *   of class declaration. And in this step we skip all callables, so by default all classes will be declared before all callables
          * To fix this issue the list of declarations is cleared at this point, and later it will be filled again in `processClassMembers`
+         *
+         * `irClass` is a source class and definitely is not a lazy class
          */
+        @OptIn(IrSymbolInternals::class)
         irClass.declarations.clear()
     }
 
@@ -220,6 +228,8 @@ class Fir2IrConverter(
             }
         }
 
+        // `irClass` is a source class and definitely is not a lazy class
+        @OptIn(IrSymbolInternals::class)
         irClass.declarations.addAll(classifierStorage.getFieldsWithContextReceiversForClass(irClass, klass))
 
         val irConstructor = klass.primaryConstructorIfAny(session)?.let {
@@ -343,6 +353,8 @@ class Fir2IrConverter(
 
     private fun bindFakeOverridesInFile(file: FirFile) {
         val irFile = declarationStorage.getIrFile(file)
+        // `irFile` definitely is not a lazy class
+        @OptIn(IrSymbolInternals::class)
         for (irDeclaration in irFile.declarations) {
             if (irDeclaration is IrClass) {
                 bindFakeOverridesInClass(irDeclaration)
@@ -350,7 +362,10 @@ class Fir2IrConverter(
         }
     }
 
+    // `irClass` is a source class and definitely is not a lazy class
+    @OptIn(IrSymbolInternals::class)
     fun bindFakeOverridesInClass(klass: IrClass) {
+        require(klass !is Fir2IrLazyClass)
         fakeOverrideGenerator.bindOverriddenSymbols(klass.declarations)
         delegatedMemberGenerator.bindDelegatedMembersOverriddenSymbols(klass)
         for (irDeclaration in klass.declarations) {
@@ -360,6 +375,8 @@ class Fir2IrConverter(
         }
     }
 
+    // `irClass` is a source class and definitely is not a lazy class
+    @OptIn(IrSymbolInternals::class)
     private fun delegatedMembers(irClass: IrClass): List<FirDeclaration> {
         return irClass.declarations.filter {
             it.origin == IrDeclarationOrigin.DELEGATED_MEMBER
@@ -419,7 +436,10 @@ class Fir2IrConverter(
          * IrClass should contain declarations in the source order, but creating of nested IrClass automatically adds created class to the list
          *   of class declaration. And in this step we skip all callables, so by default all classes will be declared before all callables
          * To fix this issue the list of declarations is cleared at this point, and later it will be filled again in `processFileAndClassMembers`
+         *
+         * `irClass` is a source class and definitely is not a lazy class
          */
+        @OptIn(IrSymbolInternals::class)
         irClass.declarations.clear()
     }
 
@@ -443,8 +463,13 @@ class Fir2IrConverter(
         containingClass: FirClass?,
         parent: IrDeclarationParent
     ) {
-        // This function is needed to preserve the source order of declaration in file
+        /*
-        // see the comment in [processClassHeaders] function
+         * This function is needed to preserve the source order of declaration in file
+         * see the comment in [processClassHeaders] function
+         *
+         * `irClass` is a source class and definitely is not a lazy class
+         */
+        @OptIn(IrSymbolInternals::class)
         fun addDeclarationToParentIfNeeded(irDeclaration: IrDeclaration) {
             when (parent) {
                 is IrFile -> parent.declarations += irDeclaration

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

@@ -41,6 +41,7 @@ import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.*
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
 import org.jetbrains.kotlin.ir.symbols.IrPropertySymbol
+import org.jetbrains.kotlin.ir.symbols.IrSymbolInternals
 import org.jetbrains.kotlin.ir.symbols.impl.IrValueParameterSymbolImpl
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.types.impl.IrErrorClassImpl
@@ -147,6 +148,9 @@ class Fir2IrVisitor(
             converter.bindFakeOverridesInClass(correspondingClass)
             conversionScope.withParent(correspondingClass) {
                 memberGenerator.convertClassContent(correspondingClass, anonymousObject)
+
+                // `correspondingClass` definitely is not a lazy class
+                @OptIn(IrSymbolInternals::class)
                 val constructor = correspondingClass.constructors.first()
                 irEnumEntry.initializerExpression = irFactory.createExpressionBody(
                     IrEnumConstructorCallImpl(
@@ -171,6 +175,8 @@ class Fir2IrVisitor(
             }
         } else if (irParentEnumClass != null && initializer == null) {
             // a default-ish enum entry whose initializer would be a delegating constructor call
+            // `irParentEnumClass` definitely is not a lazy class
+            @OptIn(IrSymbolInternals::class)
             val constructor = irParentEnumClass.defaultConstructor
                 ?: error("Assuming that default constructor should exist and be converted at this point")
             enumEntry.convertWithOffsets { startOffset, endOffset ->
@@ -325,6 +331,8 @@ class Fir2IrVisitor(
 
     override fun visitCodeFragment(codeFragment: FirCodeFragment, data: Any?): IrElement {
         val irClass = classifierStorage.getCachedIrCodeFragment(codeFragment)!!
+        // class for code fragment definitely is not a lazy class
+        @OptIn(IrSymbolInternals::class)
         val irFunction = irClass.declarations.firstIsInstance<IrSimpleFunction>()
 
         declarationStorage.enterScope(irFunction.symbol)
@@ -362,6 +370,8 @@ class Fir2IrVisitor(
                         startOffset,
                         endOffset,
                         anonymousClassType,
+                        // a class for an anonymous object definitely is not a lazy class
+                        @OptIn(IrSymbolInternals::class)
                         irAnonymousObject.constructors.first().symbol,
                         irAnonymousObject.typeParameters.size,
                         origin = IrStatementOrigin.OBJECT_LITERAL

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

@@ -157,6 +157,8 @@ class IrBuiltInsOverFir(
     }
 
     private val intrinsicConstAnnotation: IrConstructorCall by lazy {
+        // class for intrinsicConst is created manually and it definitely is not a lazy class
+        @OptIn(IrSymbolInternals::class)
         val constructor = intrinsicConst.constructors.single()
         IrConstructorCallImpl.Companion.fromSymbolOwner(intrinsicConst.defaultType, constructor)
     }
@@ -305,10 +307,17 @@ class IrBuiltInsOverFir(
                 returnType: IrType,
                 vararg valueParameterTypes: Pair<String, IrType>,
                 isIntrinsicConst: Boolean = false,
-            ) =
+            ): IrSimpleFunctionSymbol {
-                createFunction(name, returnType, valueParameterTypes, origin = BUILTIN_OPERATOR, isIntrinsicConst = isIntrinsicConst).also {
+                return createFunction(
+                    name, returnType, valueParameterTypes,
+                    origin = BUILTIN_OPERATOR,
+                    isIntrinsicConst = isIntrinsicConst
+                ).also {
+                    // `kotlinInternalIrPackageFragment` definitely is not a lazy class
+                    @OptIn(IrSymbolInternals::class)
                     declarations.add(it)
                 }.symbol
+            }
 
             primitiveFloatingPointIrTypes.forEach { fpType ->
                 _ieee754equalsFunByOperandType[fpType.classifierOrFail] = addBuiltinOperatorSymbol(
@@ -369,6 +378,8 @@ class IrBuiltInsOverFir(
                     typeParameters = listOf(typeParameter),
                     origin = BUILTIN_OPERATOR
                 ).also {
+                    // `kotlinInternalIrPackageFragment` definitely is not a lazy class
+                    @OptIn(IrSymbolInternals::class)
                     declarations.add(it)
                 }.symbol
             }
@@ -557,6 +568,8 @@ class IrBuiltInsOverFir(
         return builtInClass.functions.filter { it.owner.name == name }.asIterable()
     }
 
+    // This function should not be called from fir2ir code
+    @IrSymbolInternals
     override fun getBinaryOperator(name: Name, lhsType: IrType, rhsType: IrType): IrSimpleFunctionSymbol {
         val definingClass = lhsType.getMaybeBuiltinClass() ?: error("Defining class not found: $lhsType")
         return definingClass.functions.single { function ->
@@ -564,6 +577,8 @@ class IrBuiltInsOverFir(
         }.symbol
     }
 
+    // This function should not be called from fir2ir code
+    @IrSymbolInternals
     override fun getUnaryOperator(name: Name, receiverType: IrType): IrSimpleFunctionSymbol {
         val definingClass = receiverType.getMaybeBuiltinClass() ?: error("Defining class not found: $receiverType")
         return definingClass.functions.single { function ->

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/generators/DataClassMembersGenerator.kt

@@ -26,6 +26,7 @@ import org.jetbrains.kotlin.ir.builders.IrGeneratorContextBase
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.IrMemberAccessExpression
 import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
+import org.jetbrains.kotlin.ir.symbols.IrSymbolInternals
 import org.jetbrains.kotlin.ir.symbols.impl.IrValueParameterSymbolImpl
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.util.*
@@ -101,6 +102,8 @@ class DataClassMembersGenerator(val components: Fir2IrComponents) : Fir2IrCompon
 
             override fun getProperty(irValueParameter: IrValueParameter?): IrProperty =
                 irValueParameter?.let {
+                    // `irClass` is a source class and definitely is not a lazy class
+                    @OptIn(IrSymbolInternals::class)
                     irClass.properties.single { irProperty ->
                         irProperty.name == irValueParameter.name && irProperty.backingField?.type == irValueParameter.type
                     }
@@ -232,6 +235,8 @@ class DataClassMembersGenerator(val components: Fir2IrComponents) : Fir2IrCompon
             return result
         }
 
+        // `irClass` is a source class and definitely is not a lazy class
+        @OptIn(IrSymbolInternals::class)
         fun generateBodies() {
             val propertyParametersCount = irClass.primaryConstructor?.explicitParameters?.size ?: 0
             val properties = irClass.properties.filter { it.backingField != null }.take(propertyParametersCount).toList()
@@ -280,6 +285,8 @@ class DataClassMembersGenerator(val components: Fir2IrComponents) : Fir2IrCompon
         fun generateComponentBody(irFunction: IrFunction) {
             irFunction.origin = origin
             val index = DataClassResolver.getComponentIndex(irFunction.name.asString())
+            // `irClass` is a source class and definitely is not a lazy class
+            @OptIn(IrSymbolInternals::class)
             val valueParameter = irClass.primaryConstructor!!.valueParameters[index - 1]
             val irProperty = irDataClassMembersGenerator.getProperty(valueParameter)
             irDataClassMembersGenerator.generateComponentFunction(irFunction, irProperty)
@@ -287,6 +294,8 @@ class DataClassMembersGenerator(val components: Fir2IrComponents) : Fir2IrCompon
 
         fun generateCopyBody(irFunction: IrFunction) {
             irFunction.origin = origin
+            // `irClass` is a source class and definitely is not a lazy class
+            @OptIn(IrSymbolInternals::class)
             irDataClassMembersGenerator.generateCopyFunction(irFunction, irClass.primaryConstructor!!.symbol)
         }
 

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/generators/Fir2IrCallableDeclarationsGenerator.kt

@@ -42,10 +42,7 @@ import org.jetbrains.kotlin.ir.declarations.impl.IrVariableImpl
 import org.jetbrains.kotlin.ir.declarations.impl.SCRIPT_K2_ORIGIN
 import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.expressions.impl.IrErrorExpressionImpl
-import org.jetbrains.kotlin.ir.symbols.IrConstructorSymbol
+import org.jetbrains.kotlin.ir.symbols.*
-import org.jetbrains.kotlin.ir.symbols.IrFieldSymbol
-import org.jetbrains.kotlin.ir.symbols.IrPropertySymbol
-import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
 import org.jetbrains.kotlin.ir.symbols.impl.*
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.util.*
@@ -1119,6 +1116,7 @@ internal fun IrDeclaration.setParent(irParent: IrDeclarationParent?) {
  *      Note that IrClass will be a parent if some declaration is declared inside anonymous initializer, because IrAnonymousInitializer
  *      is not a IrDeclarationParent
  */
+@OptIn(IrSymbolInternals::class)
 internal fun addDeclarationToParent(declaration: IrDeclaration, irParent: IrDeclarationParent?) {
     if (irParent == null) return
     when (irParent) {

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/generators/Fir2IrClassifiersGenerator.kt

@@ -167,6 +167,8 @@ class Fir2IrClassifiersGenerator(val components: Fir2IrComponents) : Fir2IrCompo
         return irClass
     }
 
+    // `irClass` is a source class and definitely is not a lazy class
+    @OptIn(IrSymbolInternals::class)
     private fun IrClass.declareTypeParameters(klass: FirClass) {
         classifierStorage.preCacheTypeParameters(klass, symbol)
         setTypeParameters(this, klass)