JS frontend: additional check for nativeSetter -- check that the return type is either Unit or a supertype of the second parameter's type.

js/js.frontend/src/org/jetbrains/k2js/resolve/KotlinJsDeclarationCheckerProvider.kt

@@ -30,6 +30,7 @@ import org.jetbrains.k2js.PredefinedAnnotation
 import org.jetbrains.jet.lang.resolve.DescriptorUtils
 import org.jetbrains.k2js.translate.utils.AnnotationsUtils
 import org.jetbrains.jet.lang.descriptors.Visibilities
+import org.jetbrains.jet.lang.types.typeUtil.isSubtypeOf
 
 public object KotlinJsDeclarationCheckerProvider : AdditionalCheckerProvider {
     override val annotationCheckers: List<AnnotationChecker> = listOf(NativeInvokeChecker(), NativeGetterChecker(), NativeSetterChecker())
@@ -76,7 +77,7 @@ private abstract class AbstractNativeIndexerChecker(
             if (firstParamClassDescriptor != KotlinBuiltIns.getInstance().getString() &&
                 !DescriptorUtils.isSubclass(firstParamClassDescriptor, KotlinBuiltIns.getInstance().getNumber())
             ) {
-                diagnosticHolder.report(ErrorsJs.NATIVE_INDEXER_KEY_SHOULD_BE_STRING_OR_NUMBER.on(declaration.getValueParameters().first, indexerKind))
+                diagnosticHolder.report(ErrorsJs.NATIVE_INDEXER_KEY_SHOULD_BE_STRING_OR_NUMBER.on(declaration.getValueParameters().firstOrNull(), indexerKind))
             }
         }
 
@@ -102,4 +103,19 @@ public class NativeGetterChecker : AbstractNativeIndexerChecker(PredefinedAnnota
     }
 }
 
-public class NativeSetterChecker : AbstractNativeIndexerChecker(PredefinedAnnotation.NATIVE_SETTER, "setter", requiredParametersCount = 2)
+public class NativeSetterChecker : AbstractNativeIndexerChecker(PredefinedAnnotation.NATIVE_SETTER, "setter", requiredParametersCount = 2) {
+    override fun additionalCheck(declaration: JetNamedFunction, descriptor: FunctionDescriptor, diagnosticHolder: DiagnosticSink) {
+        super.additionalCheck(declaration, descriptor, diagnosticHolder)
+
+        val returnType = descriptor.getReturnType()
+        if (KotlinBuiltIns.isUnit(returnType)) return
+
+        val parameters = descriptor.getValueParameters()
+        if (parameters.size() < 2) return
+
+        val secondParameterType = parameters.get(1).getType()
+        if (secondParameterType isSubtypeOf returnType) return
+
+        diagnosticHolder.report(ErrorsJs.NATIVE_SETTER_WRONG_RETURN_TYPE.on(declaration))
+    }
+}

js/js.frontend/src/org/jetbrains/k2js/resolve/diagnostics/DefaultErrorMessagesJs.kt

@@ -29,6 +29,7 @@ private val DIAGNOSTIC_FACTORY_TO_RENDERER by Delegates.lazy {
         put(ErrorsJs.NATIVE_INDEXER_KEY_SHOULD_BE_STRING_OR_NUMBER, "Native {0}''s first parameter type should be ''kotlin.String'' or subtype of ''kotlin.Number''", Renderers.STRING)
         put(ErrorsJs.NATIVE_INDEXER_CAN_NOT_HAVE_DEFAULT_ARGUMENTS, "Native {0}''s parameter can not have default value", Renderers.STRING)
         put(ErrorsJs.NATIVE_GETTER_RETURN_TYPE_SHOULD_BE_NULLABLE, "Native getter''s return type should be nullable")
+        put(ErrorsJs.NATIVE_SETTER_WRONG_RETURN_TYPE, "Native setter''s return type should be ''Unit'' or a supertype of the second parameter''s type")
         put(ErrorsJs.NATIVE_INDEXER_WRONG_PARAMETER_COUNT, "Expected {0} parameters for native {1}", Renderers.TO_STRING, Renderers.STRING)
         put(ErrorsJs.JSCODE_ERROR, "JavaScript: {0}", Renderers.TO_STRING, Renderers.TO_STRING)
         put(ErrorsJs.JSCODE_WARNING, "JavaScript: {0}", Renderers.TO_STRING, Renderers.TO_STRING)

js/js.frontend/src/org/jetbrains/k2js/resolve/diagnostics/ErrorsJs.java

@@ -36,6 +36,7 @@ public interface ErrorsJs {
     DiagnosticFactory1<JetElement, String> NATIVE_INDEXER_KEY_SHOULD_BE_STRING_OR_NUMBER = DiagnosticFactory1.create(ERROR, DECLARATION_SIGNATURE_OR_DEFAULT);
     DiagnosticFactory1<JetElement, String> NATIVE_INDEXER_CAN_NOT_HAVE_DEFAULT_ARGUMENTS = DiagnosticFactory1.create(ERROR, DECLARATION_SIGNATURE_OR_DEFAULT);
     DiagnosticFactory0<JetDeclaration> NATIVE_GETTER_RETURN_TYPE_SHOULD_BE_NULLABLE = DiagnosticFactory0.create(ERROR, DECLARATION_RETURN_TYPE);
+    DiagnosticFactory0<JetDeclaration> NATIVE_SETTER_WRONG_RETURN_TYPE = DiagnosticFactory0.create(ERROR, DECLARATION_RETURN_TYPE);
     DiagnosticFactory2<JetElement, Integer, String> NATIVE_INDEXER_WRONG_PARAMETER_COUNT = DiagnosticFactory2.create(ERROR, DECLARATION_SIGNATURE_OR_DEFAULT);
     DiagnosticFactory2<JetExpression, String, List<TextRange>> JSCODE_ERROR = DiagnosticFactory2.create(ERROR, JsCodePositioningStrategy.INSTANCE$);
     DiagnosticFactory2<JetExpression, String, List<TextRange>> JSCODE_WARNING = DiagnosticFactory2.create(WARNING, JsCodePositioningStrategy.INSTANCE$);