On Tue, Mar 11, 2025 at 5:04 PM Patrick Palka <ppa...@redhat.com> wrote:
> 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:
>
Indeed, I got confused by the name (v being for vector), and the friend
overload is called.
We are also calling begin on input_range twice, which is not guaranteed to
work in general,
but seem to be well-defined in this case.
>
> 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
> >
> >
> >
