Closure and boxing return value

idea/src/org/jetbrains/jet/codegen/ClosureCodegen.java

@@ -104,6 +104,7 @@ public class ClosureCodegen {
 
     private void generateBridge(String className, FunctionDescriptor funDescriptor, ClassVisitor cv) {
         final Method bridge = erasedInvokeSignature(funDescriptor);
+        final Method delegate = invokeSignature(funDescriptor);
 
         final MethodVisitor mv = cv.visitMethod(Opcodes.ACC_PUBLIC, "invoke", bridge.getDescriptor(), typeMapper.genericSignature(funDescriptor), new String[0]);
         mv.visitCode();
@@ -120,7 +121,9 @@ public class ClosureCodegen {
             count++;
         }
 
-        iv.invokespecial(className, "invoke", invokeSignature(funDescriptor).getDescriptor());
+        iv.invokespecial(className, "invoke", delegate.getDescriptor());
+        StackValue.onStack(delegate.getReturnType()).put(JetTypeMapper.TYPE_OBJECT, iv);
+
         iv.areturn(JetTypeMapper.TYPE_OBJECT);
 
         mv.visitMaxs(0, 0);

idea/src/org/jetbrains/jet/codegen/StackValue.java

@@ -140,6 +140,9 @@ public abstract class StackValue {
             box(this.type, type, v);
         }
         else if (this.type.getSort() == Type.OBJECT && type.getSort() <= Type.DOUBLE) {
+            if (this.type.equals(JetTypeMapper.TYPE_OBJECT)) {
+                v.checkcast(Type.getObjectType("java/lang/Number"));
+            }
             unbox(type, v);
         }
         else {

idea/testData/codegen/classes/simplestClosureAndBoxing.jet

+fun box() : String {
+    return if (int_invoker( { 7 } ) == 7) "OK" else "fail"
+}
+
+fun int_invoker(gen : {() : Int}) : Int {
+    return gen()
+}

idea/tests/org/jetbrains/jet/codegen/ClosuresGenTest.java

@@ -7,4 +7,8 @@ public class ClosuresGenTest extends CodegenTestCase {
     public void testSimplestClosure() throws Exception {
         blackBoxFile("classes/simplestClosure.jet");
     }
+
+    public void testSimplestClosureAndBoxing() throws Exception {
+        blackBoxFile("classes/simplestClosureAndBoxing.jet");
+    }
 }