Error when pass "enum" in a function with variable arguments

I'm reading the book Head First C and I am the part about the variable arguments.

I wrote the following code:

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>

enum drink {
    MUDSLIDE, FUZZY_NAVEL, MONKEY_GLAND, ZOMBIE
};

double price(enum drink d) {
    switch(d) {
    case MUDSLIDE:
        return 6.79;
    case FUZZY_NAVEL:
        return 5.31;
    case MONKEY_GLAND:
        return 4.82;
    case ZOMBIE:
        return 5.89;
    }
    return 0;
}

double calc(int args, ...) {
    double total = 0;

    va_list ap;
    va_start(ap, args);

    int i;
    for (i = 0; i < args; i++) {
        int currentDrink = va_arg(ap, int);
        total += price((drink) currentDrink);
    }

    va_end(ap);
    return total;
}

int main() {
    printf("Price is %.2f\n", calc(2, MONKEY_GLAND, MUDSLIDE));
    return 0;
}

The code compiles and works perfectly.

But... There are two different lines of my solution with the book.

My:

int currentDrink = va_arg(ap, int);
total += price((drink) currentDrink);

Book:

enum drink currentDrink = va_arg(ap, enum drink);
total += price(currentDrink);

I tried to use the solution proposed in the book, but the error during execution and reports a warning: 'drink' is promoted to 'int' when passed through '...'

The book is used gcc compiler on linux. I am using gcc on Windows.

Question: What is the reason I was unable to compile the code proposed in the book?

Edit There configured wrong. Was using a C++ compiler was thinking of using a C. But the question remains: why in C++ results in a warning and error in the execution?