fix wrong enum conversion in variant function 'convert(bool* ok'

When the conversion function was invoked and
the variant type was already an enum, the conversion failed.

This commit will fix it. Added missing test case for this behaviour.

Fixes #53

src/rttr/detail/variant/variant_impl.h

@@ -307,13 +307,26 @@ RTTR_INLINE detail::enable_if_t<!std::is_arithmetic<T>::value && !std::is_enum<T
 template<typename T>
 RTTR_INLINE detail::enable_if_t<std::is_enum<T>::value, T> variant::convert_impl(bool* ok) const
 {
-    variant var = type::get<T>();
-    auto wrapper = std::ref(var);
-    const bool could_convert = convert<std::reference_wrapper<variant>>(wrapper);
-    if (ok)
-        *ok = could_convert;
+    const auto target_type = type::get<T>();
+    if (get_type() == target_type)
+    {
+        T result;
+        const auto could_convert = convert<T>(result);
+        if (ok)
+            *ok = could_convert;
+
+        return result;
+    }
+    else
+    {
+        variant var = type::get<T>();
+        auto wrapper = std::ref(var);
+        const auto could_convert = convert<std::reference_wrapper<variant>>(wrapper);
+        if (ok)
+            *ok = could_convert;
 
-    return var.get_value<T>();
+        return var.get_value<T>();
+    }
 }
 
 /////////////////////////////////////////////////////////////////////////////////////////

src/unit_tests/variant/variant_conv_test.cpp

@@ -92,12 +92,24 @@ struct other_derived : virtual base
     RTTR_ENABLE(base)
 };
 
+enum class test_enum
+{
+    first = 1,
+    second = 2
+};
+
 } // end anonymous namespace
 
 RTTR_REGISTRATION
 {
     type::register_converter_func(convert_to_string);
     type::register_converter_func(convert_to_vector);
+
+    registration::enumeration<test_enum>("test_enum")
+        (
+            value("first", test_enum::first),
+            value("second", test_enum::second)
+    );
 }
 
 /////////////////////////////////////////////////////////////////////////////////////////
@@ -671,3 +683,17 @@ TEST_CASE("variant test - convert from wrapped value", "[variant]")
 }
 
 /////////////////////////////////////////////////////////////////////////////////////////
+
+TEST_CASE("variant test - convert from enum", "[variant]")
+{
+    auto ok = false;
+    rttr::variant var = type::get<test_enum>().get_enumeration().name_to_value("second");
+    test_enum converted = var.convert<test_enum>(&ok);
+
+    CHECK(ok == true);
+    CHECK(converted != test_enum::first);
+    CHECK(converted == test_enum::second);
+    CHECK(static_cast<int>(converted) == 2);
+}
+
+/////////////////////////////////////////////////////////////////////////////////////////