Allow no else in annotated when-statements

compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/PatternMatchingTypingVisitor.java

@@ -70,6 +70,10 @@ public class PatternMatchingTypingVisitor extends ExpressionTypingVisitor {
     }
 
     public JetTypeInfo visitWhenExpression(JetWhenExpression expression, ExpressionTypingContext contextWithExpectedType, boolean isStatement) {
+        if (isStatement) {
+            contextWithExpectedType.trace.record(BindingContext.STATEMENT, expression);
+        }
+
         DataFlowUtils.recordExpectedType(contextWithExpectedType.trace, expression, contextWithExpectedType.expectedType);
 
         ExpressionTypingContext context = contextWithExpectedType.replaceExpectedType(NO_EXPECTED_TYPE).replaceContextDependency(INDEPENDENT);

compiler/testData/diagnostics/tests/when/AnnotatedWhenStatement.kt

@@ -0,0 +1,8 @@
+fun foo(a: Int) {
+    [ann]
+    when (a) {
+        1 -> {}
+    }
+}
+
+annotation class ann

compiler/tests/org/jetbrains/jet/checkers/JetDiagnosticsTestGenerated.java

@@ -5888,6 +5888,11 @@ public class JetDiagnosticsTestGenerated extends AbstractDiagnosticsTestWithEage
                 JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), "org.jetbrains.jet.generators.tests.GenerateTests", new File("compiler/testData/diagnostics/tests/when"), Pattern.compile("^(.+)\\.kt$"), true);
             }
             
+            @TestMetadata("AnnotatedWhenStatement.kt")
+            public void testAnnotatedWhenStatement() throws Exception {
+                doTest("compiler/testData/diagnostics/tests/when/AnnotatedWhenStatement.kt");
+            }
+            
             @TestMetadata("NoElseExpectedUnit.kt")
             public void testNoElseExpectedUnit() throws Exception {
                 doTest("compiler/testData/diagnostics/tests/when/NoElseExpectedUnit.kt");

js/js.translator/src/org/jetbrains/k2js/translate/expression/ExpressionVisitor.java

@@ -138,7 +138,10 @@ public final class ExpressionVisitor extends TranslatorVisitor<JsNode> {
             @NotNull TranslationContext context) {
         JetExpression expressionInside = expression.getExpression();
         if (expressionInside != null) {
-            return expressionInside.accept(this, context);
+            JsNode translated = expressionInside.accept(this, context);
+            if (translated != null) {
+                return translated;
+            }
         }
         return context.program().getEmptyStatement();
     }