Question

This should be self explanatory. I’m trying to implement a distribution sort, and the MSVC compiler is crashing. It seems to be a specific case to do with my SFINAE to detect a member function, this doesn’t appear to happen if I don’t pass indexert to a function, nor if I replace has_get_index. It also doesn’t happen if I remove either of the remaining indexer overloads. The problem does remain if sortable has a getIndex() const member.

1>test.cpp(34): fatal error C1001: An internal error has occurred in the compiler.
1>  (compiler file 'msc1.cpp', line 1420)
1>   To work around this problem, try simplifying or changing the program near the locations listed above.

(There are no “locations listed above”) A minimal test case is:

#include <vector>
#include <iterator>
#include <type_traits>

#ifndef HAS_MEM_FUNC //SFINAE (or maybe it is?)
#define HAS_MEM_FUNC(name, func)                                        \
    template<typename T>                                                \
    struct name {                                                       \
        typedef char yes[1];                                            \
        typedef char no [2];                                            \
        template <typename C> static yes& test( typename C::func ) ;    \
        template <typename C> static no&  test(...);                    \
        static bool const value = sizeof(test<T>(0)) == sizeof(yes);    \
    }
#endif
HAS_MEM_FUNC(has_get_index,getIndex);

//default indexer undefined
template <class T>
double indexer(...);
//indexer for objects that have a "T::getIndex() const" member
template <class T>
double indexer(const typename std::enable_if<has_get_index<T>::value,T>::type& b) {
    return b.getIndex();
};

template<class indexert> 
void function(indexert indexeri)
{}

struct sortable {};

int main () {
    function(indexer<sortable>); //line 34
}

Answer 1

This probably isn’t what you intended:

template <typename C> static yes& test( typename C::func ) ;

With typename you tell the compiler that C::func will be a type. In reality it will be a function, and putting a function name there in the parameter declaration doesn’t make any sense.

Did you maybe intend to use typeof instead of typename?