static inline void function has warning "control reaches end of non-void function"

Question

I currently have the following function in C:

static inline void *cmyk_to_rgb(int *dest, int *cmyk)
{
    double c = cmyk[0] / 100.0;
    double m = cmyk[1] / 100.0;
    double y = cmyk[2] / 100.0;
    double k = cmyk[3] / 100.0;

    c = c * (1 - k) + k;
    m = m * (1 - k) + k;
    y = y * (1 - k) + k;

    dest[0] = ROUND((1 - c) * 255);
    dest[1] = ROUND((1 - m) * 255);
    dest[2] = ROUND((1 - y) * 255);
}

When compiling, I am warned that

warning: control reaches end of non-void function [-Wreturn-type]

I've tried adding an explicit return at the end of the function body and that results in an outright error. What is the proper way to resolve this warning? Any solutions I've found online involve adding a return statement where the function is supposed to return some value (int etc.), but that is not the case here.

Answer 1

void * is not void

Change your first line to

static inline void cmyk_to_rgb(int *dest, int *cmyk)

void * is some pointer that isn't specified as being a particular type. Not returning a value from a function specified as returning int * would give you a similar error.