[K/JS] fix(KT-53569): skip double traversing for nested annotation classes.

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/AnnotationImplementationTransformer.kt

@@ -47,22 +47,31 @@ abstract class AnnotationImplementationTransformer(val context: BackendContext,
 
 
     override fun visitClassNew(declaration: IrClass): IrStatement {
-        declaration.takeIf { declaration.isAnnotationClass }?.constructors?.singleOrNull()?.apply {
-            // Compatibility hack. Now, frontend generates constructor body for annotations and makes them open
-            // but, if one gets annotation from pre-1.6.20 klib, it would have no constructor body and would be final,
-            // so we need to fix it
-            if (body == null) {
-                declaration.modality = Modality.OPEN
-                body = context.createIrBuilder(symbol)
-                    .irBlockBody(SYNTHETIC_OFFSET, SYNTHETIC_OFFSET) {
-                        +irDelegatingConstructorCall(context.irBuiltIns.anyClass.owner.constructors.single())
-                        +IrInstanceInitializerCallImpl(startOffset, endOffset, declaration.symbol, context.irBuiltIns.unitType)
-                    }
-            }
-        }
+        declaration.addConstructorBodyForCompatibility()
         return super.visitClassNew(declaration)
     }
 
+    protected fun IrClass.addConstructorBodyForCompatibility() {
+        if (!isAnnotationClass) return
+        val primaryConstructor = constructors.singleOrNull() ?: return
+
+        if (primaryConstructor.body != null) return
+        // Compatibility hack. Now, frontend generates constructor body for annotations and makes them open
+        // but, if one gets annotation from pre-1.6.20 klib, it would have no constructor body and would be final,
+        // so we need to fix it
+        modality = Modality.OPEN
+        primaryConstructor.body = context.createIrBuilder(symbol)
+            .irBlockBody(SYNTHETIC_OFFSET, SYNTHETIC_OFFSET) {
+                +irDelegatingConstructorCall(context.irBuiltIns.anyClass.owner.constructors.single())
+                +IrInstanceInitializerCallImpl(
+                    startOffset,
+                    endOffset,
+                    this@addConstructorBodyForCompatibility.symbol,
+                    context.irBuiltIns.unitType
+                )
+            }
+    }
+
     abstract fun chooseConstructor(implClass: IrClass, expression: IrConstructorCall) : IrConstructor
 
     override fun visitConstructorCall(expression: IrConstructorCall): IrExpression {

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/JsAnnotationImplementationLowering.kt

@@ -40,10 +40,12 @@ class JsAnnotationImplementationTransformer(val jsContext: JsIrBackendContext) :
         compilationException("Should not be called", implClass)
 
     override fun visitClassNew(declaration: IrClass): IrStatement {
-        if (declaration.isAnnotationClass) {
-            implementGeneratedFunctions(declaration, declaration)
+        return declaration.apply {
+            if (isAnnotationClass) {
+                implementGeneratedFunctions(this, this)
+            }
+            addConstructorBodyForCompatibility()
         }
-        return super.visitClassNew(declaration)
     }
 
     private val arraysContentEquals: Map<IrType, IrSimpleFunctionSymbol> =

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/BoxJsTestGenerated.java

@@ -39,6 +39,12 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
         public void testAnnotationClass() throws Exception {
             runTest("js/js.translator/testData/box/annotation/annotationClass.kt");
         }
+
+        @Test
+        @TestMetadata("multipleEqualMethodsBug.kt")
+        public void testMultipleEqualMethodsBug() throws Exception {
+            runTest("js/js.translator/testData/box/annotation/multipleEqualMethodsBug.kt");
+        }
     }
 
     @Nested

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

@@ -39,6 +39,12 @@ public class FirJsTestGenerated extends AbstractFirJsTest {
         public void testAnnotationClass() throws Exception {
             runTest("js/js.translator/testData/box/annotation/annotationClass.kt");
         }
+
+        @Test
+        @TestMetadata("multipleEqualMethodsBug.kt")
+        public void testMultipleEqualMethodsBug() throws Exception {
+            runTest("js/js.translator/testData/box/annotation/multipleEqualMethodsBug.kt");
+        }
     }
 
     @Nested

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

@@ -39,6 +39,12 @@ public class IrBoxJsTestGenerated extends AbstractIrBoxJsTest {
         public void testAnnotationClass() throws Exception {
             runTest("js/js.translator/testData/box/annotation/annotationClass.kt");
         }
+
+        @Test
+        @TestMetadata("multipleEqualMethodsBug.kt")
+        public void testMultipleEqualMethodsBug() throws Exception {
+            runTest("js/js.translator/testData/box/annotation/multipleEqualMethodsBug.kt");
+        }
     }
 
     @Nested

js/js.translator/testData/box/annotation/multipleEqualMethodsBug.kt

@@ -0,0 +1,11 @@
+// IGNORE_BACKEND: JS
+// EXPECTED_REACHABLE_NODES: 1280
+package foo
+
+annotation class Parent {
+    annotation class Child
+}
+
+fun box(): String {
+    return if (Parent.Child() == Parent.Child()) "OK" else "FAIL"
+}