[K/JS] fix(KT-46643): prevent removal of setter for overridden external field.

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/dce/Dce.kt

@@ -77,7 +77,8 @@ private fun IrDeclaration.addRootsTo(
             }
         }
         this is IrSimpleFunction -> {
-            if (correspondingPropertySymbol?.owner?.isExported(context) == true) {
+            val correspondingProperty = correspondingPropertySymbol?.owner ?: return
+            if (correspondingProperty.isExported(context)) {
                 acceptVoid(nestedVisitor)
             }
         }

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/dce/UsefulDeclarationProcessor.kt

@@ -185,6 +185,10 @@ abstract class UsefulDeclarationProcessor(
             }
         }
 
+        if (declaration is IrSimpleFunction && declaration.isAccessorForOverriddenExternalField()) {
+            declaration.enqueue(declaration.correspondingPropertySymbol!!.owner, "overrides external property")
+        }
+
         // A hack to enforce property lowering.
         // Until a getter is accessed it doesn't get moved to the declaration list.
         if (declaration is IrProperty) {
@@ -197,6 +201,14 @@ abstract class UsefulDeclarationProcessor(
         }
     }
 
+    private fun IrSimpleFunction.isAccessorForOverriddenExternalField(): Boolean {
+        return correspondingPropertySymbol?.owner?.isExternalOrOverriddenExternal() ?: false
+    }
+
+    private fun IrProperty.isExternalOrOverriddenExternal(): Boolean {
+        return isEffectivelyExternal() || overriddenSymbols.any { it.owner.isExternalOrOverriddenExternal() }
+    }
+
     protected open fun handleAssociatedObjects(): Unit = Unit
 
     fun collectDeclarations(rootDeclarations: Iterable<IrDeclaration>): Set<IrDeclaration> {

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/JsClassGenerator.kt

@@ -416,7 +416,7 @@ fun IrSimpleFunction?.shouldExportAccessor(context: JsIrBackendContext): Boolean
 
     if (parentAsClass.isExported(context)) return true
 
-    return overriddenStableProperty(context)
+    return isAccessorOfOverriddenStableProperty(context)
 }
 
 fun IrSimpleFunction.overriddenStableProperty(context: JsIrBackendContext): Boolean {
@@ -429,10 +429,14 @@ fun IrSimpleFunction.overriddenStableProperty(context: JsIrBackendContext): Bool
     return overridesExternal() || property.getJsName() != null
 }
 
-private fun IrSimpleFunction.overridesExternal(): Boolean {
+fun IrSimpleFunction.isAccessorOfOverriddenStableProperty(context: JsIrBackendContext): Boolean {
+    return overriddenStableProperty(context) || correspondingPropertySymbol!!.owner.overridesExternal()
+}
+
+private fun IrOverridableDeclaration<*>.overridesExternal(): Boolean {
     if (this.isEffectivelyExternal()) return true
 
-    return this.overriddenSymbols.any { it.owner.overridesExternal() }
+    return overriddenSymbols.any { (it.owner as IrOverridableDeclaration<*>).overridesExternal() }
 }
 
 private val IrClassifierSymbol.isInterface get() = (owner as? IrClass)?.isInterface == true

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

@@ -7498,6 +7498,12 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
             runTest("js/js.translator/testData/box/native/externalNestedEnum.kt");
         }
 
+        @Test
+        @TestMetadata("externalValWithOverridenVar.kt")
+        public void testExternalValWithOverridenVar() throws Exception {
+            runTest("js/js.translator/testData/box/native/externalValWithOverridenVar.kt");
+        }
+
         @Test
         @TestMetadata("inheritanceFromNativeClass.kt")
         public void testInheritanceFromNativeClass() throws Exception {

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

@@ -7970,6 +7970,12 @@ public class FirJsTestGenerated extends AbstractFirJsTest {
             runTest("js/js.translator/testData/box/native/externalNestedEnum.kt");
         }
 
+        @Test
+        @TestMetadata("externalValWithOverridenVar.kt")
+        public void testExternalValWithOverridenVar() throws Exception {
+            runTest("js/js.translator/testData/box/native/externalValWithOverridenVar.kt");
+        }
+
         @Test
         @TestMetadata("inheritanceFromNativeClass.kt")
         public void testInheritanceFromNativeClass() throws Exception {

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

@@ -7970,6 +7970,12 @@ public class IrBoxJsTestGenerated extends AbstractIrBoxJsTest {
             runTest("js/js.translator/testData/box/native/externalNestedEnum.kt");
         }
 
+        @Test
+        @TestMetadata("externalValWithOverridenVar.kt")
+        public void testExternalValWithOverridenVar() throws Exception {
+            runTest("js/js.translator/testData/box/native/externalValWithOverridenVar.kt");
+        }
+
         @Test
         @TestMetadata("inheritanceFromNativeClass.kt")
         public void testInheritanceFromNativeClass() throws Exception {

js/js.tests/tests-gen/org/jetbrains/kotlin/js/testOld/wasm/semantics/JsTranslatorWasmTestGenerated.java

@@ -125,6 +125,11 @@ public class JsTranslatorWasmTestGenerated extends AbstractJsTranslatorWasmTest
             runTest("js/js.translator/testData/box/native/classObject.kt");
         }
 
+        @TestMetadata("externalValWithOverridenVar.kt")
+        public void testExternalValWithOverridenVar() throws Exception {
+            runTest("js/js.translator/testData/box/native/externalValWithOverridenVar.kt");
+        }
+
         @TestMetadata("kt2209.kt")
         public void testKt2209() throws Exception {
             runTest("js/js.translator/testData/box/native/kt2209.kt");

js/js.translator/testData/box/native/externalValWithOverridenVar.js

@@ -0,0 +1,3 @@
+function Base() {
+    this.foo = "K"
+}

js/js.translator/testData/box/native/externalValWithOverridenVar.kt

@@ -0,0 +1,91 @@
+// KT-46643
+// IGNORE_BACKEND: WASM
+// WITH_STDLIB
+
+import kotlin.reflect.KProperty
+
+external interface IBase {
+    val foo: String
+}
+
+external abstract class Base : IBase
+
+open class A : Base() {
+    override var foo: String = "Error: A setter was not called."
+        set(k) { result = "O$k"}
+
+    lateinit var result: String
+}
+
+open class B : Base() {
+    override val foo: String = "OK"
+
+    open val result: String get() = foo
+}
+
+class C : B() {
+    override var foo: String = "Error: C setter was not called."
+        set(k) { result = "O$k"}
+
+    override lateinit var result: String
+}
+
+open class D : B() {
+    override val foo: String = "OK"
+}
+
+open class E : D() {
+    override var foo: String = "Error: E setter was not called."
+        set(k) { result = "O$k"}
+
+    override lateinit var result: String
+}
+
+open class F: B() {
+    override var foo: String by CustomDelegator
+
+    private object CustomDelegator {
+        operator fun getValue(thisRef: Any?, property: KProperty<*>): String {
+            return "Error: F setter was not called."
+        }
+
+        operator fun setValue(thisRef: Any?, property: KProperty<*>, value: String) {
+            result = "O$value"
+        }
+
+        lateinit var result: String
+    }
+
+    override val result: String get() = CustomDelegator.result
+}
+
+class G(val b: B): IBase by b {
+    val result: String get() = b.result
+}
+
+fun box(): String {
+    val a = A()
+    if (a.result != "OK") return a.foo
+
+    val b = B()
+    if (b.result != "OK") return b.foo
+
+    val c = C()
+    if (c.result != "OK") return c.foo
+
+    val d = D()
+    if (d.result != "OK") return d.foo
+
+    val e = E()
+    if (e.result != "OK") return e.foo
+
+    try {
+        val f = F()
+        return "Failed: it should not work for now, because of delegating objects initialization order"
+    } catch (e: Throwable) {}
+
+    val g = G(e)
+    if (g.result != "OK") return g.foo
+
+    return "OK"
+}