[K/JS] Add ability to use is checks on external objects

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsIntrinsics.kt

@@ -95,6 +95,7 @@ class JsIntrinsics(private val irBuiltIns: IrBuiltIns, val context: JsIrBackendC
 
     val jsInstanceOf = getInternalFunction("jsInstanceOfIntrinsic")
     val jsTypeOf = getInternalFunction("jsTypeOf")
+    val isExternalObject = getInternalFunction("isExternalObject")
 
     // Number conversions:
 

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

@@ -53,6 +53,7 @@ class TypeOperatorLowering(val context: JsIrBackendContext) : BodyLoweringPass {
     private val isObjectSymbol get() = context.intrinsics.isObjectSymbol
 
     private val instanceOfIntrinsicSymbol = context.intrinsics.jsInstanceOf
+    private val isExternalObjectSymbol = context.intrinsics.isExternalObject
     private val typeOfIntrinsicSymbol = context.intrinsics.jsTypeOf
     private val jsClassIntrinsicSymbol = context.intrinsics.jsClass
 
@@ -270,6 +271,7 @@ class TypeOperatorLowering(val context: JsIrBackendContext) : BodyLoweringPass {
                             generateInterfaceCheck(argument, toType)
                         }
                     }
+                    toType.isExternalObject() -> generateIsExternalObject(argument, toType)
                     else -> generateNativeInstanceOf(argument, toType)
                 }
             }
@@ -360,6 +362,14 @@ class TypeOperatorLowering(val context: JsIrBackendContext) : BodyLoweringPass {
                 }
             }
 
+            private fun generateIsExternalObject(argument: IrExpression, toType: IrType): IrExpression {
+                val irType = wrapTypeReference(toType)
+                return JsIrBuilder.buildCall(isExternalObjectSymbol).apply {
+                    putValueArgument(0, argument)
+                    putValueArgument(1, irType)
+                }
+            }
+
             private fun generateNativeInstanceOf(argument: IrExpression, toType: IrType): IrExpression {
                 val irType = wrapTypeReference(toType)
                 return JsIrBuilder.buildCall(instanceOfIntrinsicSymbol).apply {

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/IrTypeUtils.kt

@@ -57,6 +57,8 @@ fun IrType.isTypeParameter() = classifierOrNull is IrTypeParameterSymbol
 
 fun IrType.isInterface() = classOrNull?.owner?.kind == ClassKind.INTERFACE
 
+fun IrType.isExternalObject() = classOrNull?.owner.let { it?.kind == ClassKind.OBJECT && it.isExternal }
+
 fun IrType.isAnnotation() = classOrNull?.owner?.kind == ClassKind.ANNOTATION_CLASS
 
 fun IrType.isFunctionOrKFunction() = isFunction() || isKFunction()

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

@@ -3824,6 +3824,12 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
             public void testSimpleIsInterface() throws Exception {
                 runTest("js/js.translator/testData/box/expression/typeCheck/simpleIsInterface.kt");
             }
+
+            @Test
+            @TestMetadata("simpleIsObject.kt")
+            public void testSimpleIsObject() throws Exception {
+                runTest("js/js.translator/testData/box/expression/typeCheck/simpleIsObject.kt");
+            }
         }
 
         @Nested

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/fir/FirJsBoxTestGenerated.java

@@ -4440,6 +4440,12 @@ public class FirJsBoxTestGenerated extends AbstractFirJsBoxTest {
             public void testSimpleIsInterface() throws Exception {
                 runTest("js/js.translator/testData/box/expression/typeCheck/simpleIsInterface.kt");
             }
+
+            @Test
+            @TestMetadata("simpleIsObject.kt")
+            public void testSimpleIsObject() throws Exception {
+                runTest("js/js.translator/testData/box/expression/typeCheck/simpleIsObject.kt");
+            }
         }
 
         @Nested

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

@@ -4546,6 +4546,12 @@ public class IrBoxJsES6TestGenerated extends AbstractIrBoxJsES6Test {
             public void testSimpleIsInterface() throws Exception {
                 runTest("js/js.translator/testData/box/expression/typeCheck/simpleIsInterface.kt");
             }
+
+            @Test
+            @TestMetadata("simpleIsObject.kt")
+            public void testSimpleIsObject() throws Exception {
+                runTest("js/js.translator/testData/box/expression/typeCheck/simpleIsObject.kt");
+            }
         }
 
         @Nested

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

@@ -4440,6 +4440,12 @@ public class IrBoxJsTestGenerated extends AbstractIrBoxJsTest {
             public void testSimpleIsInterface() throws Exception {
                 runTest("js/js.translator/testData/box/expression/typeCheck/simpleIsInterface.kt");
             }
+
+            @Test
+            @TestMetadata("simpleIsObject.kt")
+            public void testSimpleIsObject() throws Exception {
+                runTest("js/js.translator/testData/box/expression/typeCheck/simpleIsObject.kt");
+            }
         }
 
         @Nested

js/js.translator/testData/box/expression/typeCheck/simpleIsObject.kt

@@ -0,0 +1,22 @@
+// EXPECTED_REACHABLE_NODES: 1403
+// IGNORE_BACKEND: JS
+
+package foo
+
+object RegularKotlinObject
+
+@JsName("Array")
+external object JsArray
+
+@JsName("Math")
+external object JsMath
+
+fun box(): String {
+    if (js("[]") !is JsArray) return "fail1"
+    if (js("[]") is JsMath) return "fail2"
+    if (js("[]") is RegularKotlinObject) return "fail3"
+    if (JsMath !is JsMath) return "fail4"
+    if (RegularKotlinObject !is RegularKotlinObject) return "fail5"
+
+    return "OK"
+}

libraries/stdlib/js-ir/runtime/typeCheckUtils.kt

@@ -239,3 +239,8 @@ internal fun isComparable(value: dynamic): Boolean {
 @OptIn(JsIntrinsic::class)
 internal fun isCharSequence(value: dynamic): Boolean =
     jsTypeOf(value) == "string" || isInterface(value, jsClassIntrinsic<CharSequence>())
+
+
+@OptIn(JsIntrinsic::class)
+internal fun isExternalObject(value: dynamic, ktExternalObject: dynamic) =
+    jsEqeqeq(value, ktExternalObject) || (jsTypeOf(ktExternalObject) == "function" && jsInstanceOf(value, ktExternalObject))