fork download

copy

#include <iostream>
using namespace std;
 
template<int k>
struct Base{
   int a = k;
};
 
struct C1 : Base<1>{};
struct C2 : Base<2>{int b;};
 
typedef Base<1> C1T;
 
 
    template<
            typename BufferType,
 
            typename VerticesType,
            VerticesType BufferType::* VerticesField = nullptr
            >
    void t(){};
 
 
int main() {
// WHY this work??
	t<C1T , int, &C1T::a>();
 
// And this not?
C1 c1;
t<C1 , int, &c1::a>();
 
// ok.
//	t< Base<1>, int, &Base<1>::a >();
 
// also, ok
t<C2 , int, &C2::b>();
	return 0;
}

prog.cpp: In function ‘int main()’:
prog.cpp:30:1: error: parse error in template argument list
 t<C1 , int, &c1::a>();
 ^
prog.cpp:30:21: error: no matching function for call to ‘t()’
 t<C1 , int, &c1::a>();
                     ^
prog.cpp:30:21: note: candidate is:
prog.cpp:21:10: note: template<class BufferType, class VerticesType, VerticesType BufferType::* VerticesField> void t()
     void t(){};
          ^
prog.cpp:21:10: note:   template argument deduction/substitution failed:
prog.cpp:30:21: error: template argument 3 is invalid
 t<C1 , int, &c1::a>();
                     ^

Standard output is empty