FIR2IR: Fix exception when local class used before declaration

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrClassifierStorage.kt

@@ -168,7 +168,7 @@ class Fir2IrClassifierStorage(
         }
     }
 
-    private fun createIrClass(klass: FirClass, parent: IrDeclarationParent? = null): IrClass {
+    private fun createLocalIrClass(klass: FirClass, parent: IrDeclarationParent? = null): IrClass {
         // NB: klass can be either FirRegularClass or FirAnonymousObject
         if (klass is FirAnonymousObject) {
             return createIrAnonymousObject(klass, irParent = parent)
@@ -434,7 +434,7 @@ class Fir2IrClassifierStorage(
         val firClass = firClassSymbol.fir
         getCachedIrClass(firClass)?.let { return it.symbol }
         if (firClass is FirAnonymousObject || firClass is FirRegularClass && firClass.visibility == Visibilities.Local) {
-            return createIrClass(firClass).symbol
+            return createLocalIrClass(firClass).symbol
         }
         val signature = signatureComposer.composeSignature(firClass)!!
         symbolTable.referenceClassIfAny(signature)?.let { irClassSymbol ->

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

@@ -221,7 +221,13 @@ class Fir2IrConverter(
     }
 
     private fun registerClassAndNestedClasses(regularClass: FirRegularClass, parent: IrDeclarationParent): IrClass {
-        val irClass = classifierStorage.registerIrClass(regularClass, parent)
+        val irClass =
+            // Local classes might be referenced before they declared (see usages of Fir2IrClassifierStorage.createLocalIrClass)
+            // So, we only need to set its parent properly
+            classifierStorage.getCachedIrClass(regularClass)?.apply {
+                this.parent = parent
+            }
+                ?: classifierStorage.registerIrClass(regularClass, parent)
         regularClass.declarations.forEach {
             if (it is FirRegularClass) {
                 registerClassAndNestedClasses(it, irClass)

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java

@@ -26508,6 +26508,12 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
             runTest("compiler/testData/codegen/box/localClasses/localClassInParameterInitializer.kt");
         }
 
+        @Test
+        @TestMetadata("localClassUsedBeforeDeclaration.kt")
+        public void testLocalClassUsedBeforeDeclaration() throws Exception {
+            runTest("compiler/testData/codegen/box/localClasses/localClassUsedBeforeDeclaration.kt");
+        }
+
         @Test
         @TestMetadata("localDataClass.kt")
         public void testLocalDataClass() throws Exception {

compiler/testData/codegen/box/localClasses/localClassUsedBeforeDeclaration.kt

@@ -0,0 +1,6 @@
+fun box(): String {
+    return object {
+        val a = A("OK")
+        inner class A(val ok: String)
+    }.a.ok
+}

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/BlackBoxCodegenTestGenerated.java

@@ -26370,6 +26370,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             runTest("compiler/testData/codegen/box/localClasses/localClassInParameterInitializer.kt");
         }
 
+        @Test
+        @TestMetadata("localClassUsedBeforeDeclaration.kt")
+        public void testLocalClassUsedBeforeDeclaration() throws Exception {
+            runTest("compiler/testData/codegen/box/localClasses/localClassUsedBeforeDeclaration.kt");
+        }
+
         @Test
         @TestMetadata("localDataClass.kt")
         public void testLocalDataClass() throws Exception {

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxCodegenTestGenerated.java

@@ -26508,6 +26508,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             runTest("compiler/testData/codegen/box/localClasses/localClassInParameterInitializer.kt");
         }
 
+        @Test
+        @TestMetadata("localClassUsedBeforeDeclaration.kt")
+        public void testLocalClassUsedBeforeDeclaration() throws Exception {
+            runTest("compiler/testData/codegen/box/localClasses/localClassUsedBeforeDeclaration.kt");
+        }
+
         @Test
         @TestMetadata("localDataClass.kt")
         public void testLocalDataClass() throws Exception {

compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -22277,6 +22277,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
             runTest("compiler/testData/codegen/box/localClasses/localClassInParameterInitializer.kt");
         }
 
+        @TestMetadata("localClassUsedBeforeDeclaration.kt")
+        public void testLocalClassUsedBeforeDeclaration() throws Exception {
+            runTest("compiler/testData/codegen/box/localClasses/localClassUsedBeforeDeclaration.kt");
+        }
+
         @TestMetadata("localDataClass.kt")
         public void testLocalDataClass() throws Exception {
             runTest("compiler/testData/codegen/box/localClasses/localDataClass.kt");

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/es6/semantics/IrJsCodegenBoxES6TestGenerated.java

@@ -17261,6 +17261,11 @@ public class IrJsCodegenBoxES6TestGenerated extends AbstractIrJsCodegenBoxES6Tes
             runTest("compiler/testData/codegen/box/localClasses/localClassInParameterInitializer.kt");
         }
 
+        @TestMetadata("localClassUsedBeforeDeclaration.kt")
+        public void testLocalClassUsedBeforeDeclaration() throws Exception {
+            runTest("compiler/testData/codegen/box/localClasses/localClassUsedBeforeDeclaration.kt");
+        }
+
         @TestMetadata("localDataClass.kt")
         public void testLocalDataClass() throws Exception {
             runTest("compiler/testData/codegen/box/localClasses/localDataClass.kt");

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/semantics/IrJsCodegenBoxTestGenerated.java

@@ -16667,6 +16667,11 @@ public class IrJsCodegenBoxTestGenerated extends AbstractIrJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/localClasses/localClassInParameterInitializer.kt");
         }
 
+        @TestMetadata("localClassUsedBeforeDeclaration.kt")
+        public void testLocalClassUsedBeforeDeclaration() throws Exception {
+            runTest("compiler/testData/codegen/box/localClasses/localClassUsedBeforeDeclaration.kt");
+        }
+
         @TestMetadata("localDataClass.kt")
         public void testLocalDataClass() throws Exception {
             runTest("compiler/testData/codegen/box/localClasses/localDataClass.kt");

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/wasm/semantics/IrCodegenBoxWasmTestGenerated.java

@@ -15963,6 +15963,11 @@ public class IrCodegenBoxWasmTestGenerated extends AbstractIrCodegenBoxWasmTest
             runTest("compiler/testData/codegen/box/localClasses/localClassInParameterInitializer.kt");
         }
 
+        @TestMetadata("localClassUsedBeforeDeclaration.kt")
+        public void testLocalClassUsedBeforeDeclaration() throws Exception {
+            runTest("compiler/testData/codegen/box/localClasses/localClassUsedBeforeDeclaration.kt");
+        }
+
         @TestMetadata("localDataClass.kt")
         public void testLocalDataClass() throws Exception {
             runTest("compiler/testData/codegen/box/localClasses/localDataClass.kt");

js/js.tests/tests-gen/org/jetbrains/kotlin/js/testNew/JsCodegenBoxTestGenerated.java

@@ -18704,6 +18704,12 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/localClasses/localClassInParameterInitializer.kt");
         }
 
+        @Test
+        @TestMetadata("localClassUsedBeforeDeclaration.kt")
+        public void testLocalClassUsedBeforeDeclaration() throws Exception {
+            runTest("compiler/testData/codegen/box/localClasses/localClassUsedBeforeDeclaration.kt");
+        }
+
         @Test
         @TestMetadata("localDataClass.kt")
         public void testLocalDataClass() throws Exception {