#include <ranges>
#include <utility>

struct Tag {};

using Sent = std::pair<Tag, int>;

bool operator==(int*, Sent);
std::ptrdiff_t operator-(int*, Sent);
std::ptrdiff_t operator-(Sent, int*);

struct Rng {
    int* begin();
    Sent end();
};

int main() {
    auto x  = std::views::cartesian_product(Rng{});
    (void) (x.begin() - std::default_sentinel); // `operator-` calls `_It._Distance_from(_It._End_tuple(...))`
    // Before: `_End_tuple` returns a `tuple<Tag, int>`, which results in an error in `_Distance_from`
    // After: `_End_tuple` returns a `tuple<Sent>` as expected
}