On Thu, 9 Nov 2023 at 16:01, Patrick Palka <ppa...@redhat.com> wrote:
>
> Tested on x86_64-pc-linux-gnu, does this look OK for trunk/13? (The
> && overloads are also missing on earlier branches, but I don't think
> it makes a difference there since all uses of that operator* are on
> lvalues before this fix.)
OK for trunk and gcc-13, thanks.
>
> -- >8 --
>
> We need to respect the value category of the repeat_view passed to these
> two functions when accessing its _M_value member. This revealed that
> the space-efficient partial specialization of __box lacks && overloads
> of operator* to match std::optional's API.
>
> PR libstdc++/112453
>
> libstdc++-v3/ChangeLog:
>
> * include/std/ranges (__detail::__box::operator*): Define &&
> overloads as well.
> (__detail::__take_of_repeat_view): Forward __r when accessing
> its _M_value member.
> (__detail::__drop_of_repeat_view): Likewise.
> * testsuite/std/ranges/repeat/1.cc (test07): New test.
> ---
> libstdc++-v3/include/std/ranges | 20 ++++++++++++++-----
> libstdc++-v3/testsuite/std/ranges/repeat/1.cc | 13 ++++++++++++
> 2 files changed, 28 insertions(+), 5 deletions(-)
>
> diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
> index 7893e3a84c9..41f95dc8f78 100644
> --- a/libstdc++-v3/include/std/ranges
> +++ b/libstdc++-v3/include/std/ranges
> @@ -250,13 +250,21 @@ namespace ranges
> { return true; };
>
> constexpr _Tp&
> - operator*() noexcept
> + operator*() & noexcept
> { return _M_value; }
>
> constexpr const _Tp&
> - operator*() const noexcept
> + operator*() const & noexcept
> { return _M_value; }
>
> + constexpr _Tp&&
> + operator*() && noexcept
> + { return std::move(_M_value); }
> +
> + constexpr const _Tp&&
> + operator*() const && noexcept
> + { return std::move(_M_value); }
> +
> constexpr _Tp*
> operator->() noexcept
> { return std::__addressof(_M_value); }
> @@ -7799,9 +7807,10 @@ namespace views::__adaptor
> using _Tp = remove_cvref_t<_Range>;
> static_assert(__is_repeat_view<_Tp>);
> if constexpr (sized_range<_Tp>)
> - return views::repeat(*__r._M_value,
> std::min(ranges::distance(__r), __n));
> + return views::repeat(*std::forward<_Range>(__r)._M_value,
> + std::min(ranges::distance(__r), __n));
> else
> - return views::repeat(*__r._M_value, __n);
> + return views::repeat(*std::forward<_Range>(__r)._M_value, __n);
> }
>
> template<typename _Range>
> @@ -7813,7 +7822,8 @@ namespace views::__adaptor
> if constexpr (sized_range<_Tp>)
> {
> auto __sz = ranges::distance(__r);
> - return views::repeat(*__r._M_value, __sz - std::min(__sz, __n));
> + return views::repeat(*std::forward<_Range>(__r)._M_value,
> + __sz - std::min(__sz, __n));
> }
> else
> return __r;
> diff --git a/libstdc++-v3/testsuite/std/ranges/repeat/1.cc
> b/libstdc++-v3/testsuite/std/ranges/repeat/1.cc
> index 30636407ee2..9551414e2c8 100644
> --- a/libstdc++-v3/testsuite/std/ranges/repeat/1.cc
> +++ b/libstdc++-v3/testsuite/std/ranges/repeat/1.cc
> @@ -2,6 +2,7 @@
>
> #include <ranges>
> #include <algorithm>
> +#include <memory>
> #include <testsuite_hooks.h>
>
> #if __cpp_lib_ranges_repeat != 202207L
> @@ -137,6 +138,17 @@ test06()
> static_assert( requires { views::repeat(move_only{}, 2); } );
> }
>
> +void
> +test07()
> +{
> + // PR libstdc++/112453
> + auto t = std::views::repeat(std::make_unique<int>(5)) |
> std::views::take(2);
> + auto d = std::views::repeat(std::make_unique<int>(5)) |
> std::views::drop(2);
> +
> + auto t2 = std::views::repeat(std::make_unique<int>(5), 4) |
> std::views::take(2);
> + auto d2 = std::views::repeat(std::make_unique<int>(5), 4) |
> std::views::drop(2);
> +}
> +
> int
> main()
> {
> @@ -146,4 +158,5 @@ main()
> static_assert(test04());
> test05();
> test06();
> + test07();
> }
> --
> 2.43.0.rc1
>
