Static assertion of `is_base_of` in templated class fails with unexpected type in MSVC

Question

I want to make sure that one of the template parameters of my class is derived of a specific (abstract) class. With this intention is wrote this

class abstract_record
    {};
        template<typename Record, typename Container = std::vector>  //requires SequenceContainer<Container> //See ISO/IEC PRF TS 19217
    class mddb_adapter : public Wt::WAbstractTableModel
    {
        static_assert(std::is_base_of<abstract_record, Record>,"Record must be derived of MDDB_Service::MDDB_Web::abstract_record");
...

But I get a compiler error:

error C2226: syntax error : unexpected type 'std::is_base_of<abstract_record,Record>'

Is this a problem of MSVC (I'm using Visual Studio 2013 Express) or did I got something wrong, e.g. how do I solve this?

Answer 1

The result of the is_base_of verification is accessible via a static nested value data member:

static_assert(std::is_base_of<abstract_record, Record>::value
//                                                    ~~~~~~^
     , "Record must be derived of MDDB_Service::MDDB_Web::abstract_record");

If your compiler supports constexpr evaluation of a conversion operator, you can instead use the below syntax:

static_assert(std::is_base_of<abstract_record, Record>{}
//                                                    ↑↑
     , "Record must be derived of MDDB_Service::MDDB_Web::abstract_record");