[K/JS] Fix problem with saving of parameter's default values after overriding ^KT-63907 Fixed

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/export/ExportModelGenerator.kt

@@ -85,6 +85,7 @@ class ExportModelGenerator(val context: JsIrBackendContext, val generateNamespac
             is Exportability.Prohibited -> ErrorDeclaration(exportability.reason)
             is Exportability.Allowed -> {
                 val parent = function.parent
+                val realOverrideTarget = function.realOverrideTarget
                 ExportedFunction(
                     function.getExportedIdentifier(),
                     returnType = exportType(function.returnType),
@@ -96,7 +97,13 @@ class ExportModelGenerator(val context: JsIrBackendContext, val generateNamespac
                     ir = function,
                     parameters = (listOfNotNull(function.extensionReceiverParameter) + function.valueParameters)
                         .filter { it.shouldBeExported() }
-                        .memoryOptimizedMap { exportParameter(it) },
+                        .memoryOptimizedMapIndexed { i, it ->
+                            exportParameter(
+                                it,
+                                it.hasDefaultValue
+                                        || realOverrideTarget.valueParameters.getOrNull(i)?.hasDefaultValue == true
+                            )
+                        }
                 )
             }
         }
@@ -106,12 +113,14 @@ class ExportModelGenerator(val context: JsIrBackendContext, val generateNamespac
         if (!constructor.isPrimary) return null
         val allValueParameters = listOfNotNull(constructor.extensionReceiverParameter) + constructor.valueParameters
         return ExportedConstructor(
-            parameters = allValueParameters.filterNot { it.isBoxParameter }.memoryOptimizedMap { exportParameter(it) },
+            parameters = allValueParameters
+                .filterNot { it.isBoxParameter }
+                .memoryOptimizedMap { exportParameter(it, it.hasDefaultValue) },
             visibility = constructor.visibility.toExportedVisibility()
         )
     }
 
-    private fun exportParameter(parameter: IrValueParameter): ExportedParameter {
+    private fun exportParameter(parameter: IrValueParameter, hasDefaultValue: Boolean): ExportedParameter {
         // Parameter names do not matter in d.ts files. They can be renamed as we like
         var parameterName = sanitizeName(parameter.name.asString(), withHash = false)
         if (parameterName in allReservedWords)
@@ -120,10 +129,13 @@ class ExportModelGenerator(val context: JsIrBackendContext, val generateNamespac
         return ExportedParameter(
             parameterName,
             exportType(parameter.type),
-            parameter.origin == JsLoweredDeclarationOrigin.JS_SHADOWED_DEFAULT_PARAMETER
+            hasDefaultValue
         )
     }
 
+    private val IrValueParameter.hasDefaultValue: Boolean
+        get() = origin == JsLoweredDeclarationOrigin.JS_SHADOWED_DEFAULT_PARAMETER
+
     private fun exportProperty(property: IrProperty): ExportedDeclaration? {
         for (accessor in listOfNotNull(property.getter, property.setter)) {
             // TODO: Report a frontend error

js/js.translator/testData/typescript-export/interfaces-in-exported-file/interfaces.d.ts

@@ -53,5 +53,18 @@ declare namespace JS_TESTS {
                 readonly "foo.ExportedChildInterface": unique symbol;
             };
         }
+        interface InterfaceWithDefaultArguments {
+            foo(x?: number): number;
+            bar(x?: number): number;
+            readonly __doNotUseOrImplementIt: {
+                readonly "foo.InterfaceWithDefaultArguments": unique symbol;
+            };
+        }
+        class ImplementorOfInterfaceWithDefaultArguments implements foo.InterfaceWithDefaultArguments {
+            constructor();
+            bar(x?: number): number;
+            foo(x?: number): number;
+            readonly __doNotUseOrImplementIt: foo.InterfaceWithDefaultArguments["__doNotUseOrImplementIt"];
+        }
     }
 }

js/js.translator/testData/typescript-export/interfaces-in-exported-file/interfaces.kt

@@ -68,9 +68,20 @@ interface InterfaceWithCompanion {
 }
 
 
+// KT-64708
 external interface ExportedParentInterface
 
-
 interface ExportedChildInterface : ExportedParentInterface {
     fun bar()
+}
+
+// KT-63907
+interface InterfaceWithDefaultArguments {
+    fun foo(x: Int = 0) = x
+    fun bar(x: Int = 0) = x
+}
+
+
+class ImplementorOfInterfaceWithDefaultArguments : InterfaceWithDefaultArguments {
+    override fun bar(x: Int) = x + 1
 }

js/js.translator/testData/typescript-export/interfaces-in-exported-file/interfaces__main.ts

@@ -3,6 +3,7 @@ import ChildTestInterfaceImpl = JS_TESTS.foo.ChildTestInterfaceImpl;
 import processInterface = JS_TESTS.foo.processInterface;
 import processOptionalInterface = JS_TESTS.foo.processOptionalInterface;
 import WithTheCompanion = JS_TESTS.foo.WithTheCompanion;
+import ImplementorOfInterfaceWithDefaultArguments = JS_TESTS.foo.ImplementorOfInterfaceWithDefaultArguments;
 
 function assert(condition: boolean) {
     if (!condition) {
@@ -23,5 +24,11 @@ function box(): string {
 
     assert(WithTheCompanion.companionFunction() == "FUNCTION")
 
+    const instance = new ImplementorOfInterfaceWithDefaultArguments()
+    assert(instance.foo() === 0);
+    assert(instance.foo(2) === 2);
+    assert(instance.bar() === 1);
+    assert(instance.bar(2) === 3);
+
     return "OK";
 }

js/js.translator/testData/typescript-export/interfaces/interfaces.d.ts

@@ -53,5 +53,18 @@ declare namespace JS_TESTS {
                 readonly "foo.ExportedChildInterface": unique symbol;
             };
         }
+        interface InterfaceWithDefaultArguments {
+            foo(x?: number): number;
+            bar(x?: number): number;
+            readonly __doNotUseOrImplementIt: {
+                readonly "foo.InterfaceWithDefaultArguments": unique symbol;
+            };
+        }
+        class ImplementorOfInterfaceWithDefaultArguments implements foo.InterfaceWithDefaultArguments {
+            constructor();
+            bar(x?: number): number;
+            foo(x?: number): number;
+            readonly __doNotUseOrImplementIt: foo.InterfaceWithDefaultArguments["__doNotUseOrImplementIt"];
+        }
     }
 }

js/js.translator/testData/typescript-export/interfaces/interfaces.kt

@@ -63,10 +63,23 @@ interface InterfaceWithCompanion {
     }
 }
 
+// KT-64708
 @JsExport
 external interface ExportedParentInterface
 
 @JsExport
 interface ExportedChildInterface : ExportedParentInterface {
     fun bar()
+}
+
+// KT-63907
+@JsExport
+interface InterfaceWithDefaultArguments {
+    fun foo(x: Int = 0) = x
+    fun bar(x: Int = 0) = x
+}
+
+@JsExport
+class ImplementorOfInterfaceWithDefaultArguments : InterfaceWithDefaultArguments {
+    override fun bar(x: Int) = x + 1
 }

js/js.translator/testData/typescript-export/interfaces/interfaces__main.ts

@@ -3,6 +3,7 @@ import ChildTestInterfaceImpl = JS_TESTS.foo.ChildTestInterfaceImpl;
 import processInterface = JS_TESTS.foo.processInterface;
 import processOptionalInterface = JS_TESTS.foo.processOptionalInterface;
 import WithTheCompanion = JS_TESTS.foo.WithTheCompanion;
+import ImplementorOfInterfaceWithDefaultArguments = JS_TESTS.foo.ImplementorOfInterfaceWithDefaultArguments;
 
 function assert(condition: boolean) {
     if (!condition) {
@@ -23,5 +24,11 @@ function box(): string {
 
     assert(WithTheCompanion.companionFunction() == "FUNCTION")
 
+    const instance = new ImplementorOfInterfaceWithDefaultArguments()
+    assert(instance.foo() === 0);
+    assert(instance.foo(2) === 2);
+    assert(instance.bar() === 1);
+    assert(instance.bar(2) === 3);
+
     return "OK";
 }