fix #346 (workaround)

see
https://github.com/Microsoft/TypeScript-wiki/blob/master/Breaking-Changes.md#extending-built-ins-like-error-array-and-map-may-no-longer-work

transpiler/src/main/java/org/jsweet/transpiler/Java2TypeScriptTranslator.java

@@ -540,8 +540,9 @@ public class Java2TypeScriptTranslator extends AbstractTreePrinter {
 			}
 
 			if (symbol != null) {
-				// @ represents a common root in case there is no common root package
-				// => pathToImportedClass cannot be null because of the common @ root
+				// '@' represents a common root in case there is no common root
+				// package => pathToImportedClass cannot be null because of the
+				// common '@' root
 				String pathToImportedClass = Util.getRelativePath(
 						"@/" + compilationUnit.packge.toString().replace('.', '/'),
 						"@/" + importedClass.toString().replace('.', '/'));
@@ -2470,6 +2471,12 @@ public class Java2TypeScriptTranslator extends AbstractTreePrinter {
 	protected void printInstanceInitialization(JCClassDecl clazz, MethodSymbol method) {
 		if (method == null || method.isConstructor()) {
 			getScope().hasDeclaredConstructor = true;
+			// this workaround will not work on all browsers (see
+			// https://github.com/Microsoft/TypeScript-wiki/blob/master/Breaking-Changes.md#extending-built-ins-like-error-array-and-map-may-no-longer-work)
+			if (context.types.isAssignable(clazz.sym.type, context.symtab.throwableType)) {
+				printIndent().print("(<any>Object).setPrototypeOf(this, " + getClassName(clazz.sym) + ".prototype);")
+						.println();
+			}
 			if (getScope().innerClassNotStatic && !getScope().enumWrapperClassScope) {
 				printIndent().print("this." + PARENT_CLASS_FIELD_NAME + " = " + PARENT_CLASS_FIELD_NAME + ";")
 						.println();

transpiler/src/main/java/org/jsweet/transpiler/extension/Java2TypeScriptAdapter.java

@@ -787,7 +787,7 @@ public class Java2TypeScriptAdapter extends PrinterAdapter {
 			case "getMessage":
 				if (targetType instanceof TypeElement) {
 					if (types().isAssignable(targetType.asType(), util().getType(Throwable.class))) {
-						print(invocationElement.getTargetExpression()).print(".message");
+						printTarget(invocationElement.getTargetExpression()).print(".message");
 						return true;
 					}
 				}

transpiler/src/test/java/org/jsweet/test/transpiler/ThrowableTests.java

@@ -21,6 +21,7 @@ import org.jsweet.transpiler.ModuleKind;
 import org.junit.Assert;
 import org.junit.Test;
 
+import source.throwable.ExtendedThrowables;
 import source.throwable.InvalidTryCatchTest;
 import source.throwable.MultipleTryCatchTest;
 import source.throwable.Throwables;
@@ -75,4 +76,11 @@ public class ThrowableTests extends AbstractTest {
 		}, getSourceFile(Throwables.class));
 	}
 
+	@Test
+	public void testExtendedThrowables() {
+		eval((handler, result) -> {
+			handler.assertNoProblems();
+		}, getSourceFile(ExtendedThrowables.class));
+	}
+	
 }

transpiler/src/test/java/source/throwable/ExtendedThrowables.java

@@ -0,0 +1,71 @@
+/* 
+ * JSweet - http://www.jsweet.org
+ * Copyright (C) 2015 CINCHEO SAS <renaud.pawlak@cincheo.fr>
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package source.throwable;
+
+public class ExtendedThrowables {
+
+	public static void main(String[] args) {
+
+		try {
+			m2();
+		} catch (MyThrowable4 t) {
+			assert t instanceof MyThrowable4;
+			assert t.getMessage().equals("message");
+			assert t.getMsg2().equals("message");
+		}
+		try {
+			if (true) {
+				throw new MyError(true);
+			}
+		} catch (MyError ex) {
+			assert ex.isValid();
+		}
+	}
+
+	static void m2() {
+		throw new MyThrowable4("message");
+	}
+
+}
+
+@SuppressWarnings("serial")
+class MyThrowable4 extends RuntimeException {
+
+	public MyThrowable4(String message) {
+		super(message);
+	}
+
+	public String getMsg2() {
+		return getMessage();
+	}
+
+}
+
+@SuppressWarnings("serial")
+class MyError extends def.js.Error {
+
+	private final boolean valid;
+
+	public MyError(boolean valid) {
+		this.valid = valid;
+	}
+
+	public boolean isValid() {
+		return valid;
+	}
+
+}