JS backend: report diagonstic message for unsupported element instead of throw exception.

#KT-6507 Fixed

compiler/testData/cli/js/diagnosticForUnhandledElements.args

@@ -0,0 +1,4 @@
+$TESTDATA_DIR$/diagnosticForUnhandledElements.kt
+-no-stdlib
+-output
+$TEMP_DIR$/out.js

compiler/testData/cli/js/diagnosticForUnhandledElements.kt

@@ -0,0 +1,18 @@
+package foo
+
+annotation class fancy
+
+[fancy]
+class Foo {
+    [fancy]
+    fun baz([fancy] foo : Int) : Int {
+        return [fancy] 1
+    }
+}
+
+fun test() {
+
+    class A {
+        fun foo(){}
+    }
+}

compiler/testData/cli/js/diagnosticForUnhandledElements.out

@@ -0,0 +1,4 @@
+WARNING: compiler/testData/cli/js/diagnosticForUnhandledElements.kt: (8, 21) Parameter 'foo' is never used
+ERROR: compiler/testData/cli/js/diagnosticForUnhandledElements.kt: (9, 16) Cannot translate (not supported yet): '[fancy] 1'
+ERROR: compiler/testData/cli/js/diagnosticForUnhandledElements.kt: (15, 5) Cannot translate (not supported yet): 'class A {...'
+COMPILATION_ERROR

compiler/tests/org/jetbrains/kotlin/cli/KotlincExecutableTestGenerated.java

@@ -183,6 +183,12 @@ public class KotlincExecutableTestGenerated extends AbstractKotlincExecutableTes
             JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/cli/js"), Pattern.compile("^(.+)\\.args$"), false);
         }
 
+        @TestMetadata("diagnosticForUnhandledElements.args")
+        public void testDiagnosticForUnhandledElements() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/cli/js/diagnosticForUnhandledElements.args");
+            doJsTest(fileName);
+        }
+
         @TestMetadata("jsExtraHelp.args")
         public void testJsExtraHelp() throws Exception {
             String fileName = JetTestUtils.navigationMetadata("compiler/testData/cli/js/jsExtraHelp.args");

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

@@ -34,6 +34,8 @@ private val DIAGNOSTIC_FACTORY_TO_RENDERER by Delegates.lazy {
         put(ErrorsJs.JSCODE_ERROR, "JavaScript: {0}", JsCallDataTextRenderer)
         put(ErrorsJs.JSCODE_WARNING, "JavaScript: {0}", JsCallDataTextRenderer)
         put(ErrorsJs.JSCODE_ARGUMENT_SHOULD_BE_CONSTANT, "Argument must be string constant")
+        put(ErrorsJs.NOT_SUPPORTED, "Cannot translate (not supported yet): ''{0}''", RenderFirstLineOfElementText)
+
 
         this
     }

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

@@ -39,6 +39,7 @@ public interface ErrorsJs {
     DiagnosticFactory1<JetExpression, JsCallData> JSCODE_ERROR = DiagnosticFactory1.create(ERROR, JsCodePositioningStrategy.INSTANCE$);
     DiagnosticFactory1<JetExpression, JsCallData> JSCODE_WARNING = DiagnosticFactory1.create(WARNING, JsCodePositioningStrategy.INSTANCE$);
     DiagnosticFactory0<JetExpression> JSCODE_ARGUMENT_SHOULD_BE_CONSTANT = DiagnosticFactory0.create(ERROR, DEFAULT);
+    DiagnosticFactory1<JetElement, JetElement> NOT_SUPPORTED = DiagnosticFactory1.create(ERROR, DEFAULT);
 
     @SuppressWarnings("UnusedDeclaration")
     Object _initializer = new Object() {

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

@@ -16,10 +16,17 @@
 
 package org.jetbrains.kotlin.js.resolve.diagnostics
 
-import org.jetbrains.kotlin.renderer.Renderer
-import org.jetbrains.kotlin.js.resolve.diagnostics.JsCallData
-import org.jetbrains.kotlin.js.resolve.diagnostics.JsCallDataWithCode
 import com.google.gwt.dev.js.rhino.Utils.isEndOfLine
+import com.intellij.psi.PsiElement
+import org.jetbrains.kotlin.renderer.Renderer
+
+object RenderFirstLineOfElementText : Renderer<PsiElement> {
+    override fun render(element: PsiElement): String {
+        val text = element.getText()
+        val index = text.indexOf('\n')
+        return if (index == -1) text else text.substring(0, index) + "..."
+    }
+}
 
 abstract class JsCallDataRenderer : Renderer<JsCallData> {
     protected abstract fun format(data: JsCallDataWithCode): String

js/js.translator/src/org/jetbrains/kotlin/js/translate/declaration/DeclarationBodyVisitor.java

@@ -63,6 +63,11 @@ public class DeclarationBodyVisitor extends TranslatorVisitor<Void> {
         return enumEntryList;
     }
 
+    @Override
+    protected Void emptyResult(@NotNull TranslationContext context) {
+        return null;
+    }
+
     @Override
     public Void visitClass(@NotNull JetClass expression, TranslationContext context) {
         return null;

js/js.translator/src/org/jetbrains/kotlin/js/translate/expression/ExpressionVisitor.java

@@ -60,6 +60,11 @@ import static org.jetbrains.kotlin.js.translate.utils.TranslationUtils.translate
 import static org.jetbrains.kotlin.resolve.BindingContextUtils.isVarCapturedInClosure;
 
 public final class ExpressionVisitor extends TranslatorVisitor<JsNode> {
+    @Override
+    protected JsNode emptyResult(@NotNull TranslationContext context) {
+        return context.getEmptyExpression();
+    }
+
     @Override
     @NotNull
     public JsNode visitConstantExpression(@NotNull JetConstantExpression expression, @NotNull TranslationContext context) {

js/js.translator/src/org/jetbrains/kotlin/js/translate/general/TranslatorVisitor.java

@@ -17,6 +17,7 @@
 package org.jetbrains.kotlin.js.translate.general;
 
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.kotlin.js.resolve.diagnostics.ErrorsJs;
 import org.jetbrains.kotlin.js.translate.context.TranslationContext;
 import org.jetbrains.kotlin.psi.JetDeclaration;
 import org.jetbrains.kotlin.psi.JetDeclarationContainer;
@@ -26,12 +27,14 @@ import org.jetbrains.kotlin.psi.JetVisitor;
 /**
  * This class is a base class for all visitors.
  */
-public class TranslatorVisitor<T> extends JetVisitor<T, TranslationContext> {
+public abstract class TranslatorVisitor<T> extends JetVisitor<T, TranslationContext> {
+
+    protected abstract T emptyResult(@NotNull TranslationContext context);
 
     @Override
-    @NotNull
     public T visitJetElement(@NotNull JetElement expression, TranslationContext context) {
-        throw new UnsupportedOperationException("Unsupported expression encountered:" + expression.toString());
+        context.bindingTrace().report(ErrorsJs.NOT_SUPPORTED.on(expression, expression));
+        return emptyResult(context);
     }
 
     public final void traverseContainer(@NotNull JetDeclarationContainer jetClass,

js/js.translator/src/org/jetbrains/kotlin/js/translate/initializer/InitializerVisitor.java

@@ -37,6 +37,11 @@ public final class InitializerVisitor extends TranslatorVisitor<Void> {
         this.result = result;
     }
 
+    @Override
+    protected Void emptyResult(@NotNull TranslationContext context) {
+        return null;
+    }
+
     @Override
     public final Void visitProperty(@NotNull JetProperty property, @NotNull TranslationContext context) {
         JetExpression initializer = property.getInitializer();