On Tue, 11 Mar 2025, Tomasz Kaminski wrote:
>
>
> On Mon, Mar 10, 2025 at 11:28 PM Patrick Palka <ppa...@redhat.com> wrote:
> Tested on x86_64-pc-linux-gnu, does this look OK for trunk?
>
> -- >8 --
>
> libstdc++-v3/ChangeLog:
>
> * include/bits/version.def (ranges_to_input): Define.
> * include/bits/version.h: Regenerate.
> * include/std/ranges (ranges::to_input_view): Define for C++26.
> (views::__detail::__can_to_input): Likewise.
> (views::_ToInput, views::to_input): Likewise.
> * testsuite/std/ranges/adaptors/to_input/1.cc: New test.
> ---
> libstdc++-v3/include/bits/version.def | 8 +
> libstdc++-v3/include/bits/version.h | 10 ++
> libstdc++-v3/include/std/ranges | 170 ++++++++++++++++++
> .../std/ranges/adaptors/to_input/1.cc | 58 ++++++
> 4 files changed, 246 insertions(+)
> create mode 100644
> libstdc++-v3/testsuite/std/ranges/adaptors/to_input/1.cc
>
> diff --git a/libstdc++-v3/include/bits/version.def
> b/libstdc++-v3/include/bits/version.def
> index 2af5a54bff2..c2b5283df89 100644
> --- a/libstdc++-v3/include/bits/version.def
> +++ b/libstdc++-v3/include/bits/version.def
> @@ -1910,6 +1910,14 @@ ftms = {
> };
> };
>
> +ftms = {
> + name = ranges_to_input;
> + values = {
> + v = 202502;
> + cxxmin = 26;
> + };
> +};
> +
> ftms = {
> name = to_string;
> values = {
> diff --git a/libstdc++-v3/include/bits/version.h
> b/libstdc++-v3/include/bits/version.h
> index 9833023cfdc..775c8642139 100644
> --- a/libstdc++-v3/include/bits/version.h
> +++ b/libstdc++-v3/include/bits/version.h
> @@ -2120,6 +2120,16 @@
> #endif /* !defined(__cpp_lib_text_encoding) &&
> defined(__glibcxx_want_text_encoding) */
> #undef __glibcxx_want_text_encoding
>
> +#if !defined(__cpp_lib_ranges_to_input)
> +# if (__cplusplus > 202302L)
> +# define __glibcxx_ranges_to_input 202502L
> +# if defined(__glibcxx_want_all) ||
> defined(__glibcxx_want_ranges_to_input)
> +# define __cpp_lib_ranges_to_input 202502L
> +# endif
> +# endif
> +#endif /* !defined(__cpp_lib_ranges_to_input) &&
> defined(__glibcxx_want_ranges_to_input) */
> +#undef __glibcxx_want_ranges_to_input
> +
> #if !defined(__cpp_lib_to_string)
> # if (__cplusplus > 202302L) && _GLIBCXX_HOSTED &&
> (__glibcxx_to_chars)
> # define __glibcxx_to_string 202306L
> diff --git a/libstdc++-v3/include/std/ranges
> b/libstdc++-v3/include/std/ranges
> index e21f5284b46..dd97d276ef0 100644
> --- a/libstdc++-v3/include/std/ranges
> +++ b/libstdc++-v3/include/std/ranges
> @@ -69,6 +69,7 @@
> #define __glibcxx_want_ranges_slide
> #define __glibcxx_want_ranges_stride
> #define __glibcxx_want_ranges_to_container
> +#define __glibcxx_want_ranges_to_input
> #define __glibcxx_want_ranges_zip
> #include <bits/version.h>
>
> @@ -10390,6 +10391,175 @@ namespace ranges
> } // namespace ranges
> #endif // __cpp_lib_ranges_cache_latest
>
> +#if __cpp_lib_ranges_to_input // C++ >= 26
> +namespace ranges
> +{
> + template<input_range _Vp>
> + requires view<_Vp>
> + class to_input_view : public view_interface<to_input_view<_Vp>>
> + {
> + _Vp _M_base = _Vp();
> +
> + template<bool _Const>
> + class _Iterator;
> +
> + public:
> + to_input_view() requires default_initializable<_Vp> = default;
> +
> + constexpr explicit
> + to_input_view(_Vp __base)
> + : _M_base(std::move(__base))
> + { }
> +
> + constexpr _Vp
> + base() const & requires copy_constructible<_Vp>
> + { return _M_base; }
> +
> + constexpr _Vp
> + base() &&
> + { return std::move(_M_base); }
> +
> + constexpr auto
> + begin() requires (!__detail::__simple_view<_Vp>)
> + { return _Iterator<false>(ranges::begin(_M_base)); }
> +
> + constexpr auto
> + begin() const requires range<const _Vp>
> + { return _Iterator<true>(ranges::begin(_M_base)); }
> +
> + constexpr auto
> + end() requires (!__detail::__simple_view<_Vp>)
> + { return ranges::end(_M_base); }
> +
> + constexpr auto
> + end() const requires range<const _Vp>
> + { return ranges::end(_M_base); }
> +
> + constexpr auto
> + size() requires sized_range<_Vp>
> + { return ranges::size(_M_base); }
> +
> + constexpr auto
> + size() const requires sized_range<const _Vp>
> + { return ranges::size(_M_base); }
> + };
> +
> + template<typename _Range>
> + to_input_view(_Range&&) -> to_input_view<views::all_t<_Range>>;
> +
> + template<input_range _Vp>
> + requires view<_Vp>
> + template<bool _Const>
> + class to_input_view<_Vp>::_Iterator
> + {
> + using _Base = __maybe_const_t<_Const, _Vp>;
> +
> + iterator_t<_Base> _M_current = iterator_t<_Base>();
> +
> + constexpr explicit
> + _Iterator(iterator_t<_Base> __current)
> + : _M_current(std::move(__current))
> + { }
> +
> + friend to_input_view;
> + friend _Iterator<!_Const>;
> +
> + public:
> + using difference_type = range_difference_t<_Base>;
> + using value_type = range_value_t<_Base>;
> + using iterator_concept = input_iterator_tag;
> +
> + _Iterator() requires default_initializable<iterator_t<_Base>> =
> default;
> +
> + _Iterator(_Iterator&&) = default;
> + _Iterator& operator=(_Iterator&&) = default;
> +
> + constexpr
> + _Iterator(_Iterator<!_Const> __i)
> + requires _Const && convertible_to<iterator_t<_Vp>,
> iterator_t<_Base>>
> + : _M_current(std::move(__i._M_current))
> + { }
> +
> + constexpr iterator_t<_Base>
> + base() &&
> + { return std::move(_M_current); }
> +
> + constexpr const iterator_t<_Base>&
> + base() const & noexcept
> + { return _M_current; }
> +
> + constexpr decltype(auto)
> + operator*() const
> + { return *_M_current; }
> +
> + constexpr _Iterator&
> + operator++()
> + {
> + ++_M_current;
> + return *this;
> + }
> +
> + constexpr void
> + operator++(int)
> + { ++*this; }
> +
> + friend constexpr bool
> + operator==(const _Iterator& __x, const sentinel_t<_Base>& __y)
> + { return __x._M_current == __y; }
> +
> + friend constexpr difference_type
> + operator-(const sentinel_t<_Base>& __y, const _Iterator& __x)
> + requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base>>
> + { return __y - __x._M_current; }
> +
> + friend constexpr difference_type
> + operator-(const _Iterator& __x, const sentinel_t<_Base>& __y)
> + requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base>>
> + { return __x._M_current - __y; }
> +
> + friend constexpr range_rvalue_reference_t<_Base>
> + iter_move(const _Iterator& __i)
> + noexcept(noexcept(ranges::iter_move(__i._M_current)))
> + { return ranges::iter_move(__i._M_current); }
> +
> + friend constexpr void
> + iter_swap(const _Iterator& __x, const _Iterator& __y)
> + noexcept(noexcept(ranges::iter_swap(__x._M_current,
> __y._M_current)))
> + requires indirectly_swappable<iterator_t<_Base>>
> + { ranges::iter_swap(__x._M_current, __y._M_current); }
> + };
> +
> + namespace views
> + {
> + namespace __detail
> + {
> + template<typename _Tp>
> + concept __can_to_input = requires {
> to_input_view(std::declval<_Tp>()); };
> + }
> +
> + struct _ToInput : __adaptor::_RangeAdaptorClosure<_ToInput>
> + {
> + template<viewable_range _Range>
> + requires __detail::__can_to_input<_Range>
> + constexpr auto
> + operator() [[nodiscard]] (_Range&& __r) const
> + {
> + if constexpr (input_range<_Range>
> + && !common_range<_Range>
> + && !forward_range<_Range>)
> + return views::all(__r);
> + else
> + return to_input_view(std::forward<_Range>(__r));
> + }
> +
> + static constexpr bool _S_has_simple_call_op = true;
> + };
> +
> + inline constexpr _ToInput to_input;
> + }
> +} // namespace ranges
> +#endif // __cpp_lib_ranges_to_input
> +
> _GLIBCXX_END_NAMESPACE_VERSION
> } // namespace std
> #endif // library concepts
> diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/to_input/1.cc
> b/libstdc++-v3/testsuite/std/ranges/adaptors/to_input/1.cc
> new file mode 100644
> index 00000000000..1e43281adb4
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/std/ranges/adaptors/to_input/1.cc
> @@ -0,0 +1,58 @@
> +// { dg-do run { target c++26 } }
> +
> +#include <ranges>
> +
> +#if __cpp_lib_ranges_to_input != 202502L
> +# error "Feature-test macro __cpp_lib_ranges_to_input has wrong value
> in <ranges>"
> +#endif
> +
> +#include <algorithm>
> +#include <vector>
> +#include <testsuite_hooks.h>
> +#include <testsuite_iterators.h>
> +
> +namespace ranges = std::ranges;
> +namespace views = std::views;
> +
> +void
> +test01()
> +{
> + std::vector<int> r{1,2,3};
> + auto v = r | views::to_input;
> + using type = decltype(v);
> + static_assert( ranges::input_range<type> &&
> !ranges::forward_range<type> );
> +
> + VERIFY( ranges::equal(v.base(), r) );
> + VERIFY( v.size() == r.size() );
> + VERIFY( v.end() == r.end() );
> + auto it = v.begin();
> + VERIFY( it != r.end() );
> + *it = 42;
> + ++it;
> + *it = 43;
> + it++;
> + ranges::iter_swap(v.begin(), it);
>
> As far as I can tell this is not invoking the iter_swap friend function, and
> instead defaulting to swap by 3 iter_moves.
> We cannot copy the iterator, but you could replace v.begin(), with
> views::to_input(v).begin() to call the overload, and
> have the same effect.
v is the to_input_view, not the vector, so both arguments are
to_input_view iterators and I'd expect the friend function gets
used here? Looks like it is, demonstrated by a static_assert(false)
added to its body:
In file included from
src/libstdc++-v3/testsuite/std/ranges/adaptors/to_input/1.cc:3:
/scratchpad/gcc-build/x86_64-pc-linux-gnu/libstdc++-v3/include/ranges: In
instantiation of ‘constexpr void std::ranges::iter_swap(const
to_input_view<ref_view<std::__debug::vector<int> > >::_Iterator<true>&, const
to_input_view<ref_view<std::__debug::vector<int> > >::_Iterator<true>&)
requires
indirectly_swappable<decltype(std::ranges::__access::__begin((declval<typename
std::__conditional<_Const>::type<const _Vp, _Vp>&>)())),
decltype(std::ranges::__access::__begin((declval<typename
std::__conditional<_Const>::type<const _Vp, _Vp>&>)()))>’:
/scratchpad/gcc-build/x86_64-pc-linux-gnu/libstdc++-v3/include/bits/iterator_concepts.h:949:15:
required from ‘constexpr void
std::ranges::__iswap::_IterSwap::operator()(_Tp&&, _Up&&) const [with _Tp =
std::ranges::to_input_view<std::ranges::ref_view<std::__debug::vector<int> >
>::_Iterator<true>; _Up =
std::ranges::to_input_view<std::ranges::ref_view<std::__debug::vector<int> >
>::_Iterator<true>&]’
949 | iter_swap(static_cast<_Tp&&>(__e1),
static_cast<_Up&&>(__e2));
|
~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/libstdc++-v3/testsuite/std/ranges/adaptors/to_input/1.cc:34:20: required
from here
34 | ranges::iter_swap(v.begin(), it);
| ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
/scratchpad/gcc-build/x86_64-pc-linux-gnu/libstdc++-v3/include/ranges:10529:21:
error: static assertion failed
10529 | { static_assert(false); ranges::iter_swap(__x._M_current,
__y._M_current); }
| ^~~~~
/scratchpad/gcc-build/x86_64-pc-linux-gnu/libstdc++-v3/include/ranges:10529:21:
note: ‘false’ evaluates to false
> + VERIFY( ranges::equal(r, (int[]){3,43,42}) );
> + *it = ranges::iter_move(it);
> + VERIFY( it == r.begin() + 2 );
> + VERIFY( r.end() - it == 1 );
> + VERIFY( it - r.end() == -1 );
> +}
> +
> +void
> +test02()
> +{
> + int x[] = {1,2,3};
> + __gnu_test::test_input_range<int> rx(x);
> + static_assert( !ranges::common_range<decltype(rx)> );
> + auto v = rx | views::to_input;
> + using type = decltype(v);
> + using type = ranges::ref_view<decltype(rx)>;
>
> I would prefer a more direct representation of this check, as
> static_assert(std::is_same_v<decltype(views::all(rx)), decltype())>);
Sounds good. The 'using' technique doesn't add much here since the type
names are short and we don't subsequently use the alias anywhere.
> +}
> +
> +int
> +main()
> +{
> + test01();
> + test02();
> +}
> --
> 2.49.0.rc1.37.ge969bc8759
>
>
>
