gistfile1.cpp

// From library

typedef void (*Callback) ( int nEvent, const char* sMessage );
void SetCallback( Callback * cbk );

// My code

void MyCallback(int nEvent, const char* sMessage) {
    // ....
}

SetCallback(MyCallback);
// No matching function for call to 'SetCallback'
// Candidate function not viable: no known conversion from 'void (int, const char *)' to 'Callback *' (aka 'void (**)(int, const char *)') for 1st argument

SetCallback(&MyCallback);
// No matching function for call to 'SetCallback'
// Candidate function not viable: no known conversion from 'void (*)(int, const char *)' to 'Callback *' (aka 'void (**)(int, const char *)') for 1st argument

SetCallback(&&MyCallback);
// No matching function for call to 'SetCallback'
// Candidate function not viable: cannot convert argument of incomplete type 'void *' to 'Callback *' (aka 'void (**)(int, const char *)')

SetCallback((Callback*)MyCallback);
SetCallback((Callback*)&MyCallback);
SetCallback((Callback*)&&MyCallback);
// They all crash when the library tries to call my callback