JS: prohibit non-abstract members of external interfaces, except for nullable properties. See KT-15308

compiler/testData/diagnostics/testsWithJsStdLib/native/nonAbstractMembersOfInterface.kt

@@ -0,0 +1,21 @@
+external interface I {
+    <!NON_ABSTRACT_MEMBER_OF_EXTERNAL_INTERFACE!>fun foo(): Unit<!> = noImpl
+
+    val a: Int?
+        get() = noImpl
+
+    var b: String?
+        get() = noImpl
+        set(value) = noImpl
+
+    <!NON_ABSTRACT_MEMBER_OF_EXTERNAL_INTERFACE!>val c: Int<!>
+        get() = noImpl
+
+    <!NON_ABSTRACT_MEMBER_OF_EXTERNAL_INTERFACE!>var d: String<!>
+        get() = noImpl
+        set(value) = noImpl
+
+    var e: dynamic
+        get() = noImpl
+        set(value) = noImpl
+}

compiler/testData/diagnostics/testsWithJsStdLib/native/nonAbstractMembersOfInterface.txt

@@ -0,0 +1,13 @@
+package
+
+public external interface I {
+    public open val a: kotlin.Int?
+    public open var b: kotlin.String?
+    public open val c: kotlin.Int
+    public open var d: kotlin.String
+    public open var e: dynamic
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open fun foo(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/testsWithJsStdLib/native/optionlBody/native.kt

@@ -11,7 +11,7 @@ external interface T {
     val baz: Int
 
     fun foo()
-    fun bar() {}
+    fun bar()
 
     companion object {
         val baz: Int

compiler/testData/diagnostics/testsWithJsStdLib/native/optionlBody/native.txt

@@ -40,7 +40,7 @@ public external object O {
 
 public external interface T {
     public abstract val baz: kotlin.Int
-    public open fun bar(): kotlin.Unit
+    public abstract fun bar(): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public abstract fun foo(): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int

compiler/testData/diagnostics/testsWithJsStdLib/native/optionlBody/nativeGetter.kt

@@ -9,5 +9,5 @@ external interface T {
     @nativeGetter
     fun foo(d: Double): String?
     @nativeGetter
-    fun bar(d: Double): String? = noImpl
+    fun bar(d: Double): String?
 }

compiler/testData/diagnostics/testsWithJsStdLib/native/optionlBody/nativeGetter.txt

@@ -4,7 +4,7 @@ package
 @kotlin.js.nativeGetter public fun kotlin.String.foo(/*0*/ n: kotlin.Int): kotlin.Int?
 
 public external interface T {
-    @kotlin.js.nativeGetter public open fun bar(/*0*/ d: kotlin.Double): kotlin.String?
+    @kotlin.js.nativeGetter public abstract fun bar(/*0*/ d: kotlin.Double): kotlin.String?
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     @kotlin.js.nativeGetter public abstract fun foo(/*0*/ d: kotlin.Double): kotlin.String?
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestWithJsStdLibGenerated.java

@@ -599,6 +599,12 @@ public class DiagnosticsTestWithJsStdLibGenerated extends AbstractDiagnosticsTes
             doTest(fileName);
         }
 
+        @TestMetadata("nonAbstractMembersOfInterface.kt")
+        public void testNonAbstractMembersOfInterface() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/testsWithJsStdLib/native/nonAbstractMembersOfInterface.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("overrideOptionalParam.kt")
         public void testOverrideOptionalParam() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/testsWithJsStdLib/native/overrideOptionalParam.kt");

js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/DefaultErrorMessagesJs.kt

@@ -73,6 +73,8 @@ private val DIAGNOSTIC_FACTORY_TO_RENDERER by lazy {
             "Overriding `external` function with optional parameters by declaration from superclass: {0}", Renderers.COMPACT)
         put(ErrorsJs.IMPLEMENTING_FUNCTION_INTERFACE, "Implementing function interface is prohibited in JavaScript")
         put(ErrorsJs.INLINE_EXTERNAL_DECLARATION, "Inline external declaration")
+        put(ErrorsJs.NON_ABSTRACT_MEMBER_OF_EXTERNAL_INTERFACE,
+            "Only nullable properties of external interfaces are allowed to be non-abstract")
 
         this
     }

js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/ErrorsJs.java

@@ -78,6 +78,8 @@ public interface ErrorsJs {
             ERROR, PositioningStrategies.DECLARATION_SIGNATURE_OR_DEFAULT);
     DiagnosticFactory0<KtDeclaration> INLINE_EXTERNAL_DECLARATION = DiagnosticFactory0.create(
             ERROR, PositioningStrategies.DECLARATION_SIGNATURE_OR_DEFAULT);
+    DiagnosticFactory0<KtDeclaration> NON_ABSTRACT_MEMBER_OF_EXTERNAL_INTERFACE = DiagnosticFactory0.create(
+            ERROR, PositioningStrategies.DECLARATION_SIGNATURE_OR_DEFAULT);
 
     @SuppressWarnings("UnusedDeclaration")
     Object _initializer = new Object() {

js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/JsExternalChecker.kt

@@ -18,7 +18,6 @@ package org.jetbrains.kotlin.js.resolve.diagnostics
 
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.descriptors.*
-import org.jetbrains.kotlin.descriptors.annotations.isInlineOnlyOrReified
 import org.jetbrains.kotlin.diagnostics.DiagnosticSink
 import org.jetbrains.kotlin.js.PredefinedAnnotation
 import org.jetbrains.kotlin.js.translate.utils.AnnotationsUtils
@@ -80,6 +79,12 @@ object JsExternalChecker : SimpleDeclarationChecker {
         if (descriptor is FunctionDescriptor && descriptor.isInline) {
             diagnosticHolder.report(ErrorsJs.INLINE_EXTERNAL_DECLARATION.on(declaration))
         }
+
+        if (descriptor is CallableMemberDescriptor && descriptor.isNonAbstractMemberOfInterface() &&
+            !descriptor.isNullableProperty()
+        ) {
+            diagnosticHolder.report(ErrorsJs.NON_ABSTRACT_MEMBER_OF_EXTERNAL_INTERFACE.on(declaration))
+        }
     }
 
     private fun isDirectlyExternal(declaration: KtDeclaration, descriptor: DeclarationDescriptor): Boolean {
@@ -96,4 +101,31 @@ object JsExternalChecker : SimpleDeclarationChecker {
         val containingDeclaration = descriptor.containingDeclaration as? ClassDescriptor ?: return false
         return AnnotationsUtils.isNativeObject(containingDeclaration)
     }
+
+    private fun CallableMemberDescriptor.isNonAbstractMemberOfInterface() =
+            modality != Modality.ABSTRACT && DescriptorUtils.isInterface(containingDeclaration) &&
+            this !is PropertyAccessorDescriptor
+
+    private fun CallableMemberDescriptor.isNullableProperty() = this is PropertyDescriptor && TypeUtils.isNullableType(type)
+
+    private fun KtDeclarationWithBody.hasValidExternalBody(bindingContext: BindingContext): Boolean {
+        if (!hasBody()) return true
+        val body = bodyExpression!!
+        return if (!hasBlockBody()) {
+            body.isNoImplExpression(bindingContext)
+        }
+        else if (body is KtBlockExpression) {
+            val statement = body.statements.singleOrNull() ?: return false
+            statement.isNoImplExpression(bindingContext)
+        }
+        else {
+            false
+        }
+    }
+
+    private fun KtExpression.isNoImplExpression(bindingContext: BindingContext): Boolean {
+        val descriptor = getResolvedCall(bindingContext)?.resultingDescriptor as? PropertyDescriptor ?: return false
+        val container = descriptor.containingDeclaration as? PackageFragmentDescriptor ?: return false
+        return container.fqNameUnsafe == NO_IMPL_PROPERTY_NAME.parent() && descriptor.name == NO_IMPL_PROPERTY_NAME.shortName()
+    }
 }