Some tests for return types

idea/src/org/jetbrains/jet/lang/cfg/JetControlFlowProcessor.java

@@ -438,6 +438,14 @@ public class JetControlFlowProcessor {
             }
         }
 
+        @Override
+        public void visitTupleExpression(JetTupleExpression expression) {
+            for (JetExpression entry : expression.getEntries()) {
+                value(entry, false);
+            }
+            builder.readNode(expression);
+        }
+
         @Override
         public void visitTypeProjection(JetTypeProjection typeProjection) {
             // TODO : Support Type Arguments. Class object may be initialized at this point");

idea/testData/checker/FunctionReturnTypes.jet

+<error>fun none()</error>
+
+fun unitEmptyInfer() {}
+fun unitEmpty() : Unit {}
+fun unitEmptyReturn() : Unit {return}
+fun unitShort() : Unit = ()
+fun unitShortConv() : Unit = 1
+fun unitShortNull() : Unit = null
+
+<error>fun intEmpty() : Int {}</error>
+fun intShortInfer() = 1
+fun intShort() : Int = 1
+fun intBlockInfer()  {1}
+fun intBlock() : Int {1}
+
+fun blockReturnUnitMismatch() : Int {<error>return</error>}
+fun blockReturnValueTypeMismatch() : Int {return <error>3.4</error>}
+fun blockReturnValueTypeMatch() : Int {return 1}