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 :(
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
