Function strlen

gil/std.str.hpp:44–49

}

static constexpr auto strlen(auto str) noexcept {
  using _impl_::idx;
  using _impl_::tmp;
  return for_(block_(idx = 0, tmp = str), true,
              ++idx)(if_(end(*tmp[*idx]))(break_(*idx)));
}

static constexpr auto strcpy(auto dst, auto src) noexcept {
  using _impl_::idx;