Clad fails to provide enough arguments for the pullback if the function's return value isn't used

[gojakuch]

reproducer:

#include "clad/Differentiator/Differentiator.h"
#include <iostream>

struct S {
    double r;

    double g(double x) {
        r = x;
        return x;
    }
};

double fn(double x, double y) {
    S s;
    s.r = y;
    s.g(x);
    return s.r; // x
}

int main() {
    double dx=0, dy=0; 
    auto df = clad::gradient(fn);
    df.execute(3, 4, &dx, &dy);
    std::cout << dx << ' ' << dy <<'\n';
}

here, the method S::g returns a double value that's not being used. in this case, Clad fails to provide enough arguments for its pullback call when generating the code.