Compiler Error C2298

'operation' : illegal operation on pointer to member function expression

A pointer to member-function expression must call the member function.

Examples

The following sample generates C2298.

// C2298.cpp
#include <stdio.h>

struct X {
   void mf() {
      puts("in X::mf");
   }

   void mf2() {
      puts("in X::mf2");
   }
};

X x;
// pointer to member functions with no params and void return in X
typedef void (X::*pmf_t)();

// a pointer to member function X::mf
void (X::*pmf)() = &X::mf;

int main() {
   int (*pf)();
   pf = x.*pmf;   // C2298
   +(x.*pmf);     // C2298

   pmf_t pf2 = &X::mf2;
   (x.*pf2)();   // uses X::mf2
   (x.*pmf)();   // uses X::mf
}

The following sample generates C2298.

// C2298_b.cpp
// compile with: /c
void F() {}

class Measure {
public:
   void SetTrackingFunction(void (Measure::*fnc)()) {
      TrackingFunction = this->*fnc;   // C2298
      TrackingFunction = fnc;   // OK
      GlobalTracker = F;   // OK
   }
private:
   void (Measure::*TrackingFunction)(void);
   void (*GlobalTracker)(void);
};