fix KT-2167 (enum generation)

#KT-2167 fixed

compiler/backend/src/org/jetbrains/jet/codegen/JetTypeMapper.java

@@ -311,6 +311,21 @@ public class JetTypeMapper {
             throw new IllegalStateException("missed something");
         }
 
+        if (descriptor instanceof ClassDescriptor) {
+            ClassDescriptor klass = (ClassDescriptor) descriptor;
+            if (klass.getKind() == ClassKind.OBJECT) {
+                if (klass.getContainingDeclaration() instanceof ClassDescriptor) {
+                    ClassDescriptor containingKlass = (ClassDescriptor) klass.getContainingDeclaration();
+                    if (containingKlass.getKind() == ClassKind.ENUM_CLASS) {
+                        return getFQName(containingKlass);
+                    }
+                }
+            }
+            else if (klass.getKind() == ClassKind.ENUM_ENTRY) {
+                return getFQName(klass.getContainingDeclaration());
+            }
+        }
+
         DeclarationDescriptor container = descriptor.getContainingDeclaration();
         Name name = descriptor.getName();
         if(JetPsiUtil.NO_NAME_PROVIDED.equals(name)) {

compiler/testData/codegen/enum/asReturnExpression.kt

@@ -0,0 +1,14 @@
+// http://youtrack.jetbrains.com/issue/KT-2167
+
+enum class Season {
+    WINTER
+    SPRING
+    SUMMER
+    AUTUMN
+}
+
+fun foo() = Season.SPRING
+
+fun box() =
+    if (foo() == Season.SPRING) "OK"
+    else "fail"

compiler/tests/org/jetbrains/jet/codegen/EnumGenTest.java

@@ -34,4 +34,9 @@ public class EnumGenTest extends CodegenTestCase {
         blackBoxFile("enum/simple.kt");
     }
 
+    public void testAsReturnExpression() {
+        blackBoxFile("enum/asReturnExpression.kt");
+    }
+
+
 }