Fix bugging disallowing optionals to hold items without copy constructors

include/rfl/parsing/Parser_optional.hpp

@@ -38,7 +38,7 @@ struct Parser<R, W, std::optional<T>, ProcessorsType> {
       if (_r.is_empty(_var)) {
         return std::optional<T>();
       }
-      const auto to_opt = [](auto&& _t) { return std::make_optional<T>(_t); };
+      const auto to_opt = [](auto&& _t) { return std::make_optional<T>(std::forward<decltype(_t)>(_t)); };
       return Parser<R, W, std::remove_cvref_t<T>, ProcessorsType>::read(_r,
                                                                         _var)
           .transform(to_opt);

tests/generic/test_optional.cpp

@@ -0,0 +1,17 @@
+#include <rfl.hpp>
+#include <string>
+#include <gtest/gtest.h>
+
+namespace test_optional {
+
+struct Person {
+    std::string name;
+    std::optional<rfl::Box<Person>> spouse;
+};
+
+TEST(generic, test_optional) {
+    rfl::Generic generic;
+    // This failed to compile due to optional copying rather than moving
+    rfl::from_generic<Person>(generic);
+}
+}  // namespace test_map