On Thu, 20 May 2021, 19:35 Patrick Palka via Libstdc++, <
libstd...@gcc.gnu.org> wrote:
> Tested on x86_64-pc-linux-gnu, does this look OK for trunk/11/10?
>
Yes/yes/yes
Thanks.
>
> libstdc++-v3/ChangeLog:
>
> PR libstdc++/100690
> * include/std/ranges (iota_view::_Sentinel::_M_distance_from):
> Split out into this member function from ...
> (iota_view::_Sentinel::operator-): ... here, for sake of access
> checking.
> * testsuite/std/ranges/iota/iota_view.cc:
> ---
> libstdc++-v3/include/std/ranges | 8 ++++++--
> libstdc++-v3/testsuite/std/ranges/iota/iota_view.cc | 11 +++++++++++
> 2 files changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/libstdc++-v3/include/std/ranges
> b/libstdc++-v3/include/std/ranges
> index 704f924557c..76add252ca6 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<char>) == 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();
> }
> --
> 2.32.0.rc0
>
>
