fix(KT-40236): compute JsName from overridden symbols.

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/AnnotationUtils.kt

@@ -8,6 +8,7 @@ package org.jetbrains.kotlin.ir.backend.js.utils
 import org.jetbrains.kotlin.ir.declarations.IrAnnotationContainer
 import org.jetbrains.kotlin.ir.declarations.IrClass
 import org.jetbrains.kotlin.ir.declarations.IrDeclarationWithName
+import org.jetbrains.kotlin.ir.declarations.IrOverridableDeclaration
 import org.jetbrains.kotlin.ir.expressions.IrClassReference
 import org.jetbrains.kotlin.ir.expressions.IrConst
 import org.jetbrains.kotlin.ir.expressions.IrConstructorCall
@@ -56,8 +57,19 @@ fun IrAnnotationContainer.isJsNativeSetter(): Boolean = hasAnnotation(JsAnnotati
 
 fun IrAnnotationContainer.isJsNativeInvoke(): Boolean = hasAnnotation(JsAnnotations.jsNativeInvoke)
 
+fun IrDeclarationWithName.getJsNameForOverriddenDeclaration(): String? {
+    val jsName = getJsName()
+
+    return when {
+        jsName != null -> jsName
+        this is IrOverridableDeclaration<*> ->
+            overriddenSymbols.firstNotNullOfOrNull { (it.owner as? IrAnnotationContainer)?.getJsName() }
+        else -> null
+    }
+}
+
 fun IrDeclarationWithName.getJsNameOrKotlinName(): Name =
-    when (val jsName = getJsName()) {
+    when (val jsName = getJsNameForOverriddenDeclaration()) {
         null -> name
         else -> Name.identifier(jsName)
     }

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/es6/semantics/IrBoxJsES6TestGenerated.java

@@ -7488,6 +7488,11 @@ public class IrBoxJsES6TestGenerated extends AbstractIrBoxJsES6Test {
             runTest("js/js.translator/testData/box/propertyOverride/exportedBaseClass.kt");
         }
 
+        @TestMetadata("externalPropertyOverride.kt")
+        public void testExternalPropertyOverride() throws Exception {
+            runTest("js/js.translator/testData/box/propertyOverride/externalPropertyOverride.kt");
+        }
+
         @TestMetadata("initOverrideInConstructor.kt")
         public void testInitOverrideInConstructor() throws Exception {
             runTest("js/js.translator/testData/box/propertyOverride/initOverrideInConstructor.kt");

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

@@ -7483,6 +7483,11 @@ public class IrBoxJsTestGenerated extends AbstractIrBoxJsTest {
             runTest("js/js.translator/testData/box/propertyOverride/exportedBaseClass.kt");
         }
 
+        @TestMetadata("externalPropertyOverride.kt")
+        public void testExternalPropertyOverride() throws Exception {
+            runTest("js/js.translator/testData/box/propertyOverride/externalPropertyOverride.kt");
+        }
+
         @TestMetadata("initOverrideInConstructor.kt")
         public void testInitOverrideInConstructor() throws Exception {
             runTest("js/js.translator/testData/box/propertyOverride/initOverrideInConstructor.kt");

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

@@ -8088,6 +8088,12 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
             runTest("js/js.translator/testData/box/propertyOverride/exportedBaseClass.kt");
         }
 
+        @Test
+        @TestMetadata("externalPropertyOverride.kt")
+        public void testExternalPropertyOverride() throws Exception {
+            runTest("js/js.translator/testData/box/propertyOverride/externalPropertyOverride.kt");
+        }
+
         @Test
         @TestMetadata("initOverrideInConstructor.kt")
         public void testInitOverrideInConstructor() throws Exception {

js/js.translator/testData/box/propertyOverride/externalPropertyOverride.kt

@@ -0,0 +1,33 @@
+external interface A {
+    @JsName("__name")
+    val name: String
+
+    @JsName("bar")
+    fun foo(): String
+}
+
+external class B: A {
+    override val name: String
+    override fun foo(): String
+}
+
+fun box(): String {
+    val c = js("{ __name: 'Frodo', bar: function() { return 'Baggins' } }")
+
+    val a: A = c
+    val b: B = c
+
+    assertEquals(a.name, "Frodo")
+    assertEquals(a.asDynamic().__name, "Frodo")
+
+    assertEquals(b.name, "Frodo")
+    assertEquals(b.asDynamic().__name, "Frodo")
+
+    assertEquals(a.foo(), "Baggins")
+    assertEquals(a.asDynamic().bar(), "Baggins")
+
+    assertEquals(b.foo(), "Baggins")
+    assertEquals(b.asDynamic().bar(), "Baggins")
+
+    return "OK"
+}