boost::gil::iterator_from_2d::operator‐‐

constexpr
iterator_from_2d&
operator‐‐() noexcept;

constexpr
iterator_from_2d
operator‐‐(int) noexcept;

constexpr
decltype(auto)
operator‐‐(this auto& self)
requires requires { self += ‐difference_type(1); };

constexpr
auto
operator‐‐(this
    auto& self,
    int)
requires requires { ‐‐self; };