fix(KT-46961): add support of nested external enums.

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

@@ -88,10 +88,9 @@ class IrElementToJsExpressionTransformer : BaseIrElementToJsNodeTransformer<JsEx
             assert(fieldParent.isEnumClass) {
                 "${field.render()} in non-external class ${fieldParent.render()}"
             }
-            return JsNameRef(
-                field.getJsNameOrKotlinName().identifier,
-                context.getNameForClass(fieldParent).makeRef()
-            ).withSource(expression, context)
+
+            val receiver = expression.receiver?.accept(this, context) ?: error("Expect expression.receiver to not be null")
+            return JsNameRef(field.getJsNameOrKotlinName().identifier, receiver).withSource(expression, context)
         }
 
         if (fieldParent is IrClass && fieldParent.isInline) {

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

@@ -6697,6 +6697,11 @@ public class IrBoxJsES6TestGenerated extends AbstractIrBoxJsES6Test {
             runTest("js/js.translator/testData/box/native/exception.kt");
         }
 
+        @TestMetadata("externalNestedEnum.kt")
+        public void testExternalNestedEnum() throws Exception {
+            runTest("js/js.translator/testData/box/native/externalNestedEnum.kt");
+        }
+
         @TestMetadata("inheritanceFromNativeClass.kt")
         public void testInheritanceFromNativeClass() throws Exception {
             runTest("js/js.translator/testData/box/native/inheritanceFromNativeClass.kt");

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

@@ -6692,6 +6692,11 @@ public class IrBoxJsTestGenerated extends AbstractIrBoxJsTest {
             runTest("js/js.translator/testData/box/native/exception.kt");
         }
 
+        @TestMetadata("externalNestedEnum.kt")
+        public void testExternalNestedEnum() throws Exception {
+            runTest("js/js.translator/testData/box/native/externalNestedEnum.kt");
+        }
+
         @TestMetadata("inheritanceFromNativeClass.kt")
         public void testInheritanceFromNativeClass() throws Exception {
             runTest("js/js.translator/testData/box/native/inheritanceFromNativeClass.kt");

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

@@ -6382,6 +6382,11 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
             runTest("js/js.translator/testData/box/native/exception.kt");
         }
 
+        @TestMetadata("externalNestedEnum.kt")
+        public void testExternalNestedEnum() throws Exception {
+            runTest("js/js.translator/testData/box/native/externalNestedEnum.kt");
+        }
+
         @TestMetadata("inheritanceFromNativeClass.kt")
         public void testInheritanceFromNativeClass() throws Exception {
             runTest("js/js.translator/testData/box/native/inheritanceFromNativeClass.kt");

js/js.translator/testData/box/native/externalNestedEnum.js

@@ -0,0 +1,6 @@
+var O = {
+    Foo: {
+        A: {},
+        B: {}
+    }
+};

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

@@ -0,0 +1,24 @@
+// KT-46961
+// IGNORE_BACKEND: JS
+
+external object O {
+    enum class Foo {
+        A, B
+    }
+}
+
+fun box(): String {
+    val a = foo(O.Foo.A)
+    val b = foo(O.Foo.B)
+
+    if (a != "!") return "fail1: $a"
+    if (b != "@") return "fail2: $b"
+
+    return "OK"
+}
+
+fun foo(x: O.Foo) = when (x) {
+    O.Foo.A -> "!"
+    O.Foo.B -> "@"
+    else -> ""
+}