Serialize function fails to be found for templated type when compiling with clang 6

[gouletr]

The following code compiles fine in VS2017, but fails in clang 6:

template <class T> class RectT {
public:
    T x, y, w, h;
}

typedef RectT<float> Rectf;

template <class Archive> void serialize(Archive& archive, Rectf& rect) {
    archive(rect.x, rect.y, rect.w, rect.h);
}

Clang 6 reports that it can't find the serialize function:

../cereal-1.2.2/include/cereal/cereal.hpp:851:9: error: static_assert failed "cereal could not find any input serialization functions for the provided type and archive combination. \n\n Types must either have a serialize function, load/save pair, or load_minimal/save_minimal pair (you may not mix these). \n Serialize functions generally have the following signature: \n\n template<class Archive> \n   void serialize(Archive & ar) \n   { \n     ar( member1, member2, member3 ); \n   } \n\n "
        static_assert(traits::detail::count_input_serializers<T, ArchiveType>::value != 0,
        ^             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../cereal-1.2.2/include/cereal/cereal.hpp:730:15: note: in instantiation of function template specialization 'cereal::InputArchive<cereal::JSONInputArchive, 0>::processImpl<RectT<float>, 0>' requested here
        self->processImpl( head );
              ^
../cereal-1.2.2/include/cereal/cereal.hpp:619:9: note: in instantiation of function template specialization 'cereal::InputArchive<cereal::JSONInputArchive, 0>::process<RectT<float> &>' requested here
        process( std::forward<Types>( args )... );
        ^
../cereal-1.2.2/include/cereal/archives/json.hpp:913:5: note: in instantiation of function template specialization 'cereal::InputArchive<cereal::JSONInputArchive, 0>::operator()<RectT<float> &>' requested here
    ar( t.value );
    ^
../cereal-1.2.2/include/cereal/cereal.hpp:807:9: note: in instantiation of function template specialization 'cereal::load<RectT<float> &>' requested here
        CEREAL_LOAD_FUNCTION_NAME(*self, t);
        ^
../cereal-1.2.2/include/cereal/macros.hpp:85:35: note: expanded from macro 'CEREAL_LOAD_FUNCTION_NAME'
#define CEREAL_LOAD_FUNCTION_NAME load
                                  ^
../cereal-1.2.2/include/cereal/cereal.hpp:730:15: note: in instantiation of function template specialization 'cereal::InputArchive<cereal::JSONInputArchive, 0>::processImpl<cereal::NameValuePair<RectT<float> &>, 0>' requested here
        self->processImpl( head );
              ^
../cereal-1.2.2/include/cereal/cereal.hpp:619:9: note: (skipping 11 contexts in backtrace; use -ftemplate-backtrace-limit=0 to see all)
        process( std::forward<Types>( args )... );
        ^

It does work for all other regular structs, why is it failing for a templated type? Since it does work properly in VS2017, that makes me believe my usage of cereal is ok, but maybe I'm wrong. Anyone else has this issue?

[gouletr]

FYI, I commented out the static_assert that checks for the intput/output serializers count in cereal.hpp, and the code compile and runs just fine. For the moment I can work around it this way when __clang__ is defined and leave it enabled for MSVC. But yeah, make kitties sad 😿

[AzothAmmo]

That's a really strange error, especially since the types are so simple. I'll have to get an up-to-date clang and see if I can reproduce it and try to debug.

[BinaryAura]

I'm getting this same with glm::vec. clang as well.