On Wed, 16 Aug 2023 at 17:05, Patrick Palka via Libstdc++
<libstd...@gcc.gnu.org> wrote:
>
> On Mon, Apr 17, 2023 at 9:39 AM Patrick Palka <ppa...@redhat.com> wrote:
> >
> > This C++23 paper fixes a bug in these views when adapting a certain kind
> > of non-forward range, and we treat it as a DR against C++20.
> >
> > Tested on x86_64-pc-linux-gnu, does this look OK for GCC 13? This
> > is an ABI change for join_view so it'd be unsuitable for backporting
> > later I think :(
>
> Ping, does this look OK for trunk?
Looks like I completely missed this one, sorry.
OK for trunk.
>
> >
> > libstdc++-v3/ChangeLog:
> >
> > * include/bits/regex.h (regex_iterator::iterator_concept):
> > Define for C++20 as per P2770R0.
> > (regex_token_iterator::iterator_concept): Likewise.
> > * include/std/ranges (__detail::__as_lvalue): Define.
> > (join_view::_Iterator): Befriend join_view.
> > (join_view::_Iterator::_M_satisfy): Use _M_get_outer
> > instead of _M_outer.
> > (join_view::_Iterator::_M_get_outer): Define.
> > (join_view::_Iterator::_Iterator): Split constructor taking
> > _Parent argument into two as per P2770R0. Remove constraint on
> > default constructor.
> > (join_view::_Iterator::_M_outer): Make this data member present
> > only when the underlying range is forward.
> > (join_view::_Iterator::operator++): Use _M_get_outer instead of
> > _M_outer.
> > (join_view::_Iterator::operator--): Use __as_lvalue helper.
> > (join_view::_Iterator::operator==): Adjust constraints as per
> > P2770R0.
> > (join_view::_Sentinel::__equal): Use _M_get_outer instead of
> > _M_outer.
> > (join_view::_M_outer): New data member when the underlying range
> > is non-forward.
> > (join_view::begin): Adjust definition as per P2770R0.
> > (join_view::end): Likewise.
> > (join_with_view::_M_outer_it): New data member when the
> > underlying range is non-forward.
> > (join_with_view::begin): Adjust definition as per P2770R0.
> > (join_with_view::end): Likewise.
> > (join_with_view::_Iterator::_M_outer_it): Make this data member
> > present only when the underlying range is forward.
> > (join_with_view::_Iterator::_M_get_outer): Define.
> > (join_with_view::_Iterator::_Iterator): Split constructor
> > taking _Parent argument into two as per P2770R0. Remove
> > constraint on default constructor.
> > (join_with_view::_Iterator::_M_update_inner): Adjust definition
> > as per P2770R0.
> > (join_with_view::_Iterator::_M_get_inner): Likewise.
> > (join_with_view::_Iterator::_M_satisfy): Adjust calls to
> > _M_get_inner. Use _M_get_outer instead of _M_outer_it.
> > (join_with_view::_Iterator::operator==): Adjust constraints
> > as per P2770R0.
> > (join_with_view::_Sentinel::operator==): Use _M_get_outer
> > instead of _M_outer_it.
> > * testsuite/std/ranges/adaptors/p2770r0.cc: New test.
> > ---
> > libstdc++-v3/include/bits/regex.h | 6 +
> > libstdc++-v3/include/std/ranges | 190 +++++++++++++-----
> > .../testsuite/std/ranges/adaptors/p2770r0.cc | 110 ++++++++++
> > 3 files changed, 257 insertions(+), 49 deletions(-)
> > create mode 100644 libstdc++-v3/testsuite/std/ranges/adaptors/p2770r0.cc
> >
> > diff --git a/libstdc++-v3/include/bits/regex.h
> > b/libstdc++-v3/include/bits/regex.h
> > index 26ac6a21c31..2d306868721 100644
> > --- a/libstdc++-v3/include/bits/regex.h
> > +++ b/libstdc++-v3/include/bits/regex.h
> > @@ -2740,6 +2740,9 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
> > typedef const value_type* pointer;
> > typedef const value_type& reference;
> > typedef std::forward_iterator_tag iterator_category;
> > +#if __cplusplus > 201703L
> > + typedef std::input_iterator_tag iterator_concept;
> > +#endif
> >
> > /**
> > * @brief Provides a singular iterator, useful for indicating
> > @@ -2869,6 +2872,9 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
> > typedef const value_type* pointer;
> > typedef const value_type& reference;
> > typedef std::forward_iterator_tag iterator_category;
> > +#if __cplusplus > 201703L
> > + typedef std::input_iterator_tag iterator_concept;
> > +#endif
> >
> > public:
> > /**
> > diff --git a/libstdc++-v3/include/std/ranges
> > b/libstdc++-v3/include/std/ranges
> > index 283d757faa4..ddcf50cc93e 100644
> > --- a/libstdc++-v3/include/std/ranges
> > +++ b/libstdc++-v3/include/std/ranges
> > @@ -2705,6 +2705,14 @@ namespace views::__adaptor
> > inline constexpr _DropWhile drop_while;
> > } // namespace views
> >
> > + namespace __detail
> > + {
> > + template<typename _Tp>
> > + constexpr _Tp&
> > + __as_lvalue(_Tp&& __t)
> > + { return static_cast<_Tp&>(__t); }
> > + } // namespace __detail
> > +
> > template<input_range _Vp>
> > requires view<_Vp> && input_range<range_reference_t<_Vp>>
> > class join_view : public view_interface<join_view<_Vp>>
> > @@ -2767,6 +2775,8 @@ namespace views::__adaptor
> > using _Parent = __detail::__maybe_const_t<_Const, join_view>;
> > using _Base = join_view::_Base<_Const>;
> >
> > + friend join_view;
> > +
> > static constexpr bool _S_ref_is_glvalue
> > = join_view::_S_ref_is_glvalue<_Const>;
> >
> > @@ -2780,9 +2790,10 @@ namespace views::__adaptor
> > return _M_parent->_M_inner._M_emplace_deref(__x);
> > };
> >
> > - for (; _M_outer != ranges::end(_M_parent->_M_base); ++_M_outer)
> > + _Outer_iter& __outer = _M_get_outer();
> > + for (; __outer != ranges::end(_M_parent->_M_base); ++__outer)
> > {
> > - auto&& __inner = __update_inner(_M_outer);
> > + auto&& __inner = __update_inner(__outer);
> > _M_inner = ranges::begin(__inner);
> > if (_M_inner != ranges::end(__inner))
> > return;
> > @@ -2811,7 +2822,36 @@ namespace views::__adaptor
> > using _Outer_iter = join_view::_Outer_iter<_Const>;
> > using _Inner_iter = join_view::_Inner_iter<_Const>;
> >
> > - _Outer_iter _M_outer = _Outer_iter();
> > + constexpr _Outer_iter&
> > + _M_get_outer()
> > + {
> > + if constexpr (forward_range<_Base>)
> > + return _M_outer;
> > + else
> > + return *_M_parent->_M_outer;
> > + }
> > +
> > + constexpr const _Outer_iter&
> > + _M_get_outer() const
> > + {
> > + if constexpr (forward_range<_Base>)
> > + return _M_outer;
> > + else
> > + return *_M_parent->_M_outer;
> > + }
> > +
> > + constexpr
> > + _Iterator(_Parent* __parent, _Outer_iter __outer) requires
> > forward_range<_Base>
> > + : _M_outer(std::move(__outer)), _M_parent(__parent)
> > + { _M_satisfy(); }
> > +
> > + constexpr explicit
> > + _Iterator(_Parent* __parent) requires (!forward_range<_Base>)
> > + : _M_parent(__parent)
> > + { _M_satisfy(); }
> > +
> > + [[no_unique_address]]
> > + __detail::__maybe_present_t<forward_range<_Base>, _Outer_iter>
> > _M_outer;
> > optional<_Inner_iter> _M_inner;
> > _Parent* _M_parent = nullptr;
> >
> > @@ -2823,13 +2863,7 @@ namespace views::__adaptor
> > = common_type_t<range_difference_t<_Base>,
> > range_difference_t<range_reference_t<_Base>>>;
> >
> > - _Iterator() requires default_initializable<_Outer_iter> = default;
> > -
> > - constexpr
> > - _Iterator(_Parent* __parent, _Outer_iter __outer)
> > - : _M_outer(std::move(__outer)),
> > - _M_parent(__parent)
> > - { _M_satisfy(); }
> > + _Iterator() = default;
> >
> > constexpr
> > _Iterator(_Iterator<!_Const> __i)
> > @@ -2857,13 +2891,13 @@ namespace views::__adaptor
> > {
> > auto&& __inner_range = [this] () -> auto&& {
> > if constexpr (_S_ref_is_glvalue)
> > - return *_M_outer;
> > + return *_M_get_outer();
> > else
> > return *_M_parent->_M_inner;
> > }();
> > if (++*_M_inner == ranges::end(__inner_range))
> > {
> > - ++_M_outer;
> > + ++_M_get_outer();
> > _M_satisfy();
> > }
> > return *this;
> > @@ -2890,9 +2924,9 @@ namespace views::__adaptor
> > && common_range<range_reference_t<_Base>>
> > {
> > if (_M_outer == ranges::end(_M_parent->_M_base))
> > - _M_inner = ranges::end(*--_M_outer);
> > - while (*_M_inner == ranges::begin(*_M_outer))
> > - *_M_inner = ranges::end(*--_M_outer);
> > + _M_inner = ranges::end(__detail::__as_lvalue(*--_M_outer));
> > + while (*_M_inner ==
> > ranges::begin(__detail::__as_lvalue(*_M_outer)))
> > + *_M_inner = ranges::end(__detail::__as_lvalue(*--_M_outer));
> > --*_M_inner;
> > return *this;
> > }
> > @@ -2911,7 +2945,7 @@ namespace views::__adaptor
> > friend constexpr bool
> > operator==(const _Iterator& __x, const _Iterator& __y)
> > requires _S_ref_is_glvalue
> > - && equality_comparable<_Outer_iter>
> > + && forward_range<_Base>
> > && equality_comparable<_Inner_iter>
> > {
> > return (__x._M_outer == __y._M_outer
> > @@ -2943,7 +2977,7 @@ namespace views::__adaptor
> > template<bool _Const2>
> > constexpr bool
> > __equal(const _Iterator<_Const2>& __i) const
> > - { return __i._M_outer == _M_end; }
> > + { return __i._M_get_outer() == _M_end; }
> >
> > sentinel_t<_Base> _M_end = sentinel_t<_Base>();
> >
> > @@ -2972,6 +3006,9 @@ namespace views::__adaptor
> > };
> >
> > _Vp _M_base = _Vp();
> > + [[no_unique_address]]
> > + __detail::__maybe_present_t<!forward_range<_Vp>,
> > + __detail::__non_propagating_cache<iterator_t<_Vp>>> _M_outer;
> > [[no_unique_address]]
> > __detail::__non_propagating_cache<remove_cv_t<_InnerRange>>
> > _M_inner;
> >
> > @@ -2994,16 +3031,25 @@ namespace views::__adaptor
> > constexpr auto
> > begin()
> > {
> > - constexpr bool __use_const
> > - = (__detail::__simple_view<_Vp>
> > - && is_reference_v<range_reference_t<_Vp>>);
> > - return _Iterator<__use_const>{this, ranges::begin(_M_base)};
> > + if constexpr (forward_range<_Vp>)
> > + {
> > + constexpr bool __use_const
> > + = (__detail::__simple_view<_Vp>
> > + && is_reference_v<range_reference_t<_Vp>>);
> > + return _Iterator<__use_const>{this, ranges::begin(_M_base)};
> > + }
> > + else
> > + {
> > + _M_outer = ranges::begin(_M_base);
> > + return _Iterator<false>{this};
> > + }
> > }
> >
> > constexpr auto
> > begin() const
> > - requires input_range<const _Vp>
> > + requires forward_range<const _Vp>
> > && is_reference_v<range_reference_t<const _Vp>>
> > + && input_range<range_reference_t<const _Vp>>
> > {
> > return _Iterator<true>{this, ranges::begin(_M_base)};
> > }
> > @@ -3022,11 +3068,11 @@ namespace views::__adaptor
> >
> > constexpr auto
> > end() const
> > - requires input_range<const _Vp>
> > + requires forward_range<const _Vp>
> > && is_reference_v<range_reference_t<const _Vp>>
> > + && input_range<range_reference_t<const _Vp>>
> > {
> > - if constexpr (forward_range<const _Vp>
> > - && is_reference_v<range_reference_t<const _Vp>>
> > + if constexpr (is_reference_v<range_reference_t<const _Vp>>
> > && forward_range<range_reference_t<const _Vp>>
> > && common_range<const _Vp>
> > && common_range<range_reference_t<const _Vp>>)
> > @@ -6948,6 +6994,9 @@ namespace views::__adaptor
> > using _InnerRange = range_reference_t<_Vp>;
> >
> > _Vp _M_base = _Vp();
> > + [[no_unique_address]]
> > + __detail::__maybe_present_t<!forward_range<_Vp>,
> > + __detail::__non_propagating_cache<iterator_t<_Vp>>> _M_outer_it;
> > __detail::__non_propagating_cache<remove_cv_t<_InnerRange>> _M_inner;
> > _Pattern _M_pattern = _Pattern();
> >
> > @@ -7035,16 +7084,25 @@ namespace views::__adaptor
> > constexpr auto
> > begin()
> > {
> > - constexpr bool __use_const = is_reference_v<_InnerRange>
> > - && __detail::__simple_view<_Vp> &&
> > __detail::__simple_view<_Pattern>;
> > - return _Iterator<__use_const>{*this, ranges::begin(_M_base)};
> > + if constexpr (forward_range<_Vp>)
> > + {
> > + constexpr bool __use_const = is_reference_v<_InnerRange>
> > + && __detail::__simple_view<_Vp> &&
> > __detail::__simple_view<_Pattern>;
> > + return _Iterator<__use_const>{*this, ranges::begin(_M_base)};
> > + }
> > + else
> > + {
> > + _M_outer_it = ranges::begin(_M_base);
> > + return _Iterator<false>{*this};
> > + }
> > }
> >
> > constexpr auto
> > begin() const
> > - requires input_range<const _Vp>
> > + requires forward_range<const _Vp>
> > && forward_range<const _Pattern>
> > && is_reference_v<range_reference_t<const _Vp>>
> > + && input_range<range_reference_t<const _Vp>>
> > { return _Iterator<true>{*this, ranges::begin(_M_base)}; }
> >
> > constexpr auto
> > @@ -7062,13 +7120,13 @@ namespace views::__adaptor
> >
> > constexpr auto
> > end() const
> > - requires input_range<const _Vp>
> > + requires forward_range<const _Vp>
> > && forward_range<const _Pattern>
> > && is_reference_v<range_reference_t<const _Vp>>
> > + && input_range<range_reference_t<const _Vp>>
> > {
> > using _InnerConstRange = range_reference_t<const _Vp>;
> > - if constexpr (forward_range<const _Vp>
> > - && forward_range<_InnerConstRange>
> > + if constexpr (forward_range<_InnerConstRange>
> > && common_range<const _Vp>
> > && common_range<_InnerConstRange>)
> > return _Iterator<true>{*this, ranges::end(_M_base)};
> > @@ -7105,35 +7163,69 @@ namespace views::__adaptor
> > static constexpr bool _S_ref_is_glvalue =
> > join_with_view::_S_ref_is_glvalue<_Const>;
> >
> > _Parent* _M_parent = nullptr;
> > - _OuterIter _M_outer_it = _OuterIter();
> > + [[no_unique_address]]
> > + __detail::__maybe_present_t<forward_range<_Base>, _OuterIter>
> > _M_outer_it;
> > variant<_PatternIter, _InnerIter> _M_inner_it;
> >
> > + constexpr _OuterIter&
> > + _M_get_outer()
> > + {
> > + if constexpr (forward_range<_Base>)
> > + return _M_outer_it;
> > + else
> > + return *_M_parent->_M_outer_it;
> > + }
> > +
> > + constexpr const _OuterIter&
> > + _M_get_outer() const
> > + {
> > + if constexpr (forward_range<_Base>)
> > + return _M_outer_it;
> > + else
> > + return *_M_parent->_M_outer_it;
> > + }
> > +
> > constexpr
> > - _Iterator(_Parent& __parent, iterator_t<_Base> __outer)
> > + _Iterator(_Parent& __parent, _OuterIter __outer)
> > + requires forward_range<_Base>
> > : _M_parent(std::__addressof(__parent)),
> > _M_outer_it(std::move(__outer))
> > {
> > - if (_M_outer_it != ranges::end(_M_parent->_M_base))
> > + if (_M_get_outer() != ranges::end(_M_parent->_M_base))
> > + {
> > + auto&& __inner = _M_update_inner();
> > + _M_inner_it.template emplace<1>(ranges::begin(__inner));
> > + _M_satisfy();
> > + }
> > + }
> > +
> > + constexpr
> > + _Iterator(_Parent& __parent)
> > + requires (!forward_range<_Base>)
> > + : _M_parent(std::__addressof(__parent))
> > + {
> > + if (_M_get_outer() != ranges::end(_M_parent->_M_base))
> > {
> > - auto&& __inner = _M_update_inner(_M_outer_it);
> > + auto&& __inner = _M_update_inner();
> > _M_inner_it.template emplace<1>(ranges::begin(__inner));
> > _M_satisfy();
> > }
> > }
> >
> > - constexpr auto&&
> > - _M_update_inner(const _OuterIter& __x)
> > + constexpr auto&
> > + _M_update_inner()
> > {
> > + _OuterIter& __outer = _M_get_outer();
> > if constexpr (_S_ref_is_glvalue)
> > - return *__x;
> > + return __detail::__as_lvalue(*__outer);
> > else
> > - return _M_parent->_M_inner._M_emplace_deref(__x);
> > + return _M_parent->_M_inner._M_emplace_deref(__outer);
> > }
> >
> > - constexpr auto&&
> > - _M_get_inner(const _OuterIter& __x)
> > + constexpr auto&
> > + _M_get_inner()
> > {
> > if constexpr (_S_ref_is_glvalue)
> > - return *__x;
> > + return __detail::__as_lvalue(*_M_get_outer());
> > else
> > return *_M_parent->_M_inner;
> > }
> > @@ -7148,16 +7240,16 @@ namespace views::__adaptor
> > if (std::get<0>(_M_inner_it) !=
> > ranges::end(_M_parent->_M_pattern))
> > break;
> >
> > - auto&& __inner = _M_update_inner(_M_outer_it);
> > + auto&& __inner = _M_update_inner();
> > _M_inner_it.template emplace<1>(ranges::begin(__inner));
> > }
> > else
> > {
> > - auto&& __inner = _M_get_inner(_M_outer_it);
> > + auto&& __inner = _M_get_inner();
> > if (std::get<1>(_M_inner_it) != ranges::end(__inner))
> > break;
> >
> > - if (++_M_outer_it == ranges::end(_M_parent->_M_base))
> > + if (++_M_get_outer() == ranges::end(_M_parent->_M_base))
> > {
> > if constexpr (_S_ref_is_glvalue)
> > _M_inner_it.template emplace<0>();
> > @@ -7196,7 +7288,7 @@ namespace views::__adaptor
> > iter_difference_t<_InnerIter>,
> > iter_difference_t<_PatternIter>>;
> >
> > - _Iterator() requires default_initializable<_OuterIter> = default;
> > + _Iterator() = default;
> >
> > constexpr
> > _Iterator(_Iterator<!_Const> __i)
> > @@ -7306,7 +7398,7 @@ namespace views::__adaptor
> > friend constexpr bool
> > operator==(const _Iterator& __x, const _Iterator& __y)
> > requires _S_ref_is_glvalue
> > - && equality_comparable<_OuterIter> &&
> > equality_comparable<_InnerIter>
> > + && forward_range<_Base> && equality_comparable<_InnerIter>
> > { return __x._M_outer_it == __y._M_outer_it && __x._M_inner_it
> > ==__y._M_inner_it; }
> >
> > friend constexpr
> > common_reference_t<iter_rvalue_reference_t<_InnerIter>,
> > @@ -7373,7 +7465,7 @@ namespace views::__adaptor
> >
> > iterator_t<__detail::__maybe_const_t<_OtherConst, _Vp>>>
> > friend constexpr bool
> > operator==(const _Iterator<_OtherConst>& __x, const _Sentinel& __y)
> > - { return __x._M_outer_it == __y._M_end; }
> > + { return __x._M_get_outer() == __y._M_end; }
> > };
> >
> > namespace views
> > diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/p2770r0.cc
> > b/libstdc++-v3/testsuite/std/ranges/adaptors/p2770r0.cc
> > new file mode 100644
> > index 00000000000..15d71b2faa9
> > --- /dev/null
> > +++ b/libstdc++-v3/testsuite/std/ranges/adaptors/p2770r0.cc
> > @@ -0,0 +1,110 @@
> > +// { dg-options "-std=gnu++20" }
> > +// { dg-do run { target c++20 } }
> > +
> > +#include <ranges>
> > +#include <algorithm>
> > +#include <regex>
> > +#include <string_view>
> > +#include <testsuite_hooks.h>
> > +
> > +namespace ranges = std::ranges;
> > +namespace views = std::views;
> > +
> > +void
> > +test01()
> > +{
> > + // Test case from LWG 3698
> > + char const text[] = "Hello";
> > + std::regex regex{"[a-z]"};
> > +
> > + auto lower
> > + = ranges::subrange(std::cregex_iterator(ranges::begin(text),
> > + ranges::end(text),
> > + regex),
> > + std::cregex_iterator{})
> > + | views::join
> > + | views::transform([](auto const& sm) {
> > + return std::string_view(sm.first, sm.second);
> > + });
> > +
> > + VERIFY( ranges::equal(lower, (std::string_view[]){"e", "l", "l", "o"}));
> > +}
> > +
> > +void
> > +test02()
> > +{
> > +#if __cpp_lib_ranges_join_with
> > + // Analogous test case from LWG 3698 for join_with_view
> > + char const text[] = "Hello";
> > + std::regex regex{"[a-z]"};
> > +
> > + auto lower
> > + = ranges::subrange(std::cregex_iterator(ranges::begin(text),
> > + ranges::end(text),
> > + regex),
> > + std::cregex_iterator{})
> > + | views::join_with(views::empty<std::sub_match<const char*>>)
> > + | views::transform([](auto const& sm) {
> > + return std::string_view(sm.first, sm.second);
> > + });
> > +
> > + VERIFY( ranges::equal(lower, (std::string_view[]){"e", "l", "l", "o"}));
> > +#endif
> > +}
> > +
> > +void
> > +test03()
> > +{
> > + // Test case from LWG 3700
> > + auto r = views::iota(0, 5) | views::split(1);
> > + auto s = views::single(r);
> > + auto j = s | views::join;
> > + auto f = j.front();
> > +}
> > +
> > +void
> > +test04()
> > +{
> > +#if __cpp_lib_ranges_join_with
> > + // Analogous test case from LWG 3700 for join_with_view
> > + auto r = views::iota(0, 5) | views::split(1);
> > + auto s = views::single(r);
> > + auto j = s |
> > views::join_with(views::empty<ranges::range_value_t<decltype(r)>>);
> > + auto f = j.front();
> > +#endif
> > +}
> > +
> > +void
> > +test05()
> > +{
> > + // Test case from LWG 3791
> > + std::vector<std::vector<int>> v = {{1}};
> > + auto r = v
> > + | views::transform([](auto& x) -> auto&& { return std::move(x); })
> > + | views::join;
> > + auto e = --r.end();
> > +}
> > +
> > +void
> > +test06()
> > +{
> > +#if __cpp_lib_ranges_join_with
> > + // Analogous test case from LWG 3791 for join_with_view
> > + std::vector<std::vector<int>> v = {{1}};
> > + auto r = v
> > + | views::transform([](auto& x) -> auto&& { return std::move(x); })
> > + | views::join_with(views::empty<int>);
> > + auto e = --r.end();
> > +#endif
> > +}
> > +
> > +int
> > +main()
> > +{
> > + test01();
> > + test02();
> > + test03();
> > + test04();
> > + test05();
> > + test06();
> > +}
> > --
> > 2.40.0.335.g9857273be0
> >
>
