Is there a way to avoid implicit conversion to void*?

Question

I'm using an API that accepts void* in certain functions. I frequently accidentally pass the wrong pointer type to the function, and of course it compiles fine, but doesn't work at runtime.

Is there a way to disable implicit conversion to void* for pointers to a certain class?

Answer 1

You can add a deleted overload for the API function:

// API function
void api(void* p) {
    // ... 
}

// Special case for nullptr
inline void api(std::nullptr_t) {
    api((void*)nullptr);
}

// Everything else is disabled
template <class ...T>
void api(T&&... t) = delete;

int main() {
    int i = 0;
    void* p = &i;
    api(p); // Compiles
    // api(&i); // Doesn't compile
}