JS: initialize fields of coroutine state machine with `undefined` value so...

JS: initialize fields of coroutine state machine with `undefined` value so that they match local variable semantics. Fix KT-15366

compiler/testData/codegen/box/coroutines/multiModule/inlineFunctionWithOptionalParam.kt

+// MODULE: lib
+// FILE: lib.kt
+inline fun foo(x: String = "OK"): String {
+    return x + x
+}
+
+// MODULE: main(lib)
+// FILE: main.kt
+// WITH_RUNTIME
+// WITH_COROUTINES
+import kotlin.coroutines.*
+
+var result = ""
+
+fun builder(c: suspend () -> Unit) {
+    c.startCoroutine(object : Continuation<Unit> {
+        override fun resume(value: Unit) {
+        }
+        override fun resumeWithException(exception: Throwable) {
+        }
+    })
+}
+
+fun box(): String {
+    builder {
+        result = foo()
+    }
+    if (result != "OKOK") return "fail: $result"
+    return "OK"
+}

compiler/testData/codegen/light-analysis/coroutines/multiModule/inlineFunctionWithOptionalParam.txt

+public final class CoroutineUtilKt {
+    public final static @org.jetbrains.annotations.NotNull method handleExceptionContinuation(@org.jetbrains.annotations.NotNull p0: kotlin.jvm.functions.Function1): kotlin.coroutines.Continuation
+    public final static @org.jetbrains.annotations.NotNull method handleResultContinuation(@org.jetbrains.annotations.NotNull p0: kotlin.jvm.functions.Function1): kotlin.coroutines.Continuation
+}
+
+
+public final class EmptyContinuation {
+    public final static field INSTANCE: EmptyContinuation
+    private method <init>(): void
+    public method resume(@org.jetbrains.annotations.Nullable p0: java.lang.Object): void
+    public method resumeWithException(@org.jetbrains.annotations.NotNull p0: java.lang.Throwable): void
+}
+
+
+public final class LibKt {
+    public synthetic static method foo$default(p0: java.lang.String, p1: int, p2: java.lang.Object): java.lang.String
+    public final static @org.jetbrains.annotations.NotNull method foo(@org.jetbrains.annotations.NotNull p0: java.lang.String): java.lang.String
+}
+
+
+public final class MainKt {
+    private static @org.jetbrains.annotations.NotNull field result: java.lang.String
+    public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
+    public final static method builder(@org.jetbrains.annotations.NotNull p0: kotlin.jvm.functions.Function1): void
+    public final static @org.jetbrains.annotations.NotNull method getResult(): java.lang.String
+    public final static method setResult(@org.jetbrains.annotations.NotNull p0: java.lang.String): void
+}

compiler/tests-ir-jvm/tests/org/jetbrains/kotlin/codegen/ir/IrBlackBoxCodegenTestGenerated.java

@@ -4933,6 +4933,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                 KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/box/coroutines/multiModule"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.JVM, true);
             }
 
+            @TestMetadata("inlineFunctionWithOptionalParam.kt")
+            public void testInlineFunctionWithOptionalParam() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/multiModule/inlineFunctionWithOptionalParam.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("simple.kt")
             public void testSimple() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/multiModule/simple.kt");

compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java

@@ -4933,6 +4933,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                 KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/box/coroutines/multiModule"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.JVM, true);
             }
 
+            @TestMetadata("inlineFunctionWithOptionalParam.kt")
+            public void testInlineFunctionWithOptionalParam() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/multiModule/inlineFunctionWithOptionalParam.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("simple.kt")
             public void testSimple() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/multiModule/simple.kt");

compiler/tests/org/jetbrains/kotlin/codegen/LightAnalysisModeCodegenTestGenerated.java

@@ -4933,6 +4933,12 @@ public class LightAnalysisModeCodegenTestGenerated extends AbstractLightAnalysis
                 KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/box/coroutines/multiModule"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.JVM, true);
             }
 
+            @TestMetadata("inlineFunctionWithOptionalParam.kt")
+            public void testInlineFunctionWithOptionalParam() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/multiModule/inlineFunctionWithOptionalParam.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("simple.kt")
             public void testSimple() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/multiModule/simple.kt");

js/js.inliner/src/org/jetbrains/kotlin/js/coroutine/CoroutineFunctionTransformer.kt

@@ -83,7 +83,7 @@ class CoroutineFunctionTransformer(private val program: JsProgram, private val f
             }
             assignToField(context.metadata.exceptionStateName, program.getNumberLiteral(globalCatchBlockIndex))
             for (localVariable in localVariables) {
-                val value = if (localVariable !in parameterNames) JsLiteral.NULL else localVariable.makeRef()
+                val value = if (localVariable !in parameterNames) Namer.getUndefinedExpression() else localVariable.makeRef()
                 assignToField(function.scope.getFieldName(localVariable), value)
             }
         }

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java

@@ -5720,6 +5720,12 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
                 KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/box/coroutines/multiModule"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.JS, true);
             }
 
+            @TestMetadata("inlineFunctionWithOptionalParam.kt")
+            public void testInlineFunctionWithOptionalParam() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/multiModule/inlineFunctionWithOptionalParam.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("simple.kt")
             public void testSimple() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/multiModule/simple.kt");