diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges index 0588bebb351..767a65c5822 100644 --- a/libstdc++-v3/include/std/ranges +++ b/libstdc++-v3/include/std/ranges @@ -499,6 +499,10 @@ namespace ranges _M_equal(const _Iterator& __x) const { return __x._M_value == _M_bound; } + constexpr auto + _M_distance_from(const _Iterator& __x) const + { return _M_bound - __x._M_value; } + _Bound _M_bound = _Bound(); public: @@ -515,12 +519,12 @@ namespace ranges friend constexpr iter_difference_t<_Winc> operator-(const _Iterator& __x, const _Sentinel& __y) requires sized_sentinel_for<_Bound, _Winc> - { return __x._M_value - __y._M_bound; } + { return -__y._M_distance_from(__x); } friend constexpr iter_difference_t<_Winc> operator-(const _Sentinel& __x, const _Iterator& __y) requires sized_sentinel_for<_Bound, _Winc> - { return -(__y - __x); } + { return __x._M_distance_from(__y); } }; _Winc _M_value = _Winc(); diff --git a/libstdc++-v3/testsuite/std/ranges/iota/iota_view.cc b/libstdc++-v3/testsuite/std/ranges/iota/iota_view.cc index be8695120ad..362ef1f7f78 100644 --- a/libstdc++-v3/testsuite/std/ranges/iota/iota_view.cc +++ b/libstdc++-v3/testsuite/std/ranges/iota/iota_view.cc @@ -80,6 +80,16 @@ test04() // Verify we optimize away the 'bound' data member of an unbounded iota_view. static_assert(sizeof(std::ranges::iota_view) == 1); +void +test05() +{ + // PR libstdc++/100690 + int x[] = {42, 42, 42}; + auto r = std::views::iota(std::ranges::begin(x), std::ranges::cbegin(x) + 3); + VERIFY( r.end() - r.begin() == 3 ); + VERIFY( r.begin() - r.end() == -3 ); +} + int main() { @@ -87,4 +97,5 @@ main() test02(); test03(); test04(); + test05(); }