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* [gcc r12-7330] libstdc++: Implement P2415R2 changes to viewable_range / views::all
@ 2022-02-22 14:38 Patrick Palka
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From: Patrick Palka @ 2022-02-22 14:38 UTC (permalink / raw)
To: gcc-cvs, libstdc++-cvs
https://gcc.gnu.org/g:5e1b17f038671df1a6580ece4cd58ef91cc1e234
commit r12-7330-g5e1b17f038671df1a6580ece4cd58ef91cc1e234
Author: Patrick Palka <ppalka@redhat.com>
Date: Tue Feb 22 09:37:58 2022 -0500
libstdc++: Implement P2415R2 changes to viewable_range / views::all
This implements the wording changes in P2415R2 "What is a view?", which
is a DR for C++20.
libstdc++-v3/ChangeLog:
* include/bits/ranges_base.h (__detail::__is_initializer_list):
Define.
(viewable_range): Adjust as per P2415R2.
* include/bits/ranges_cmp.h (__cpp_lib_ranges): Adjust value.
* include/std/ranges (owning_view): Define as per P2415R2.
(enable_borrowed_range<owning_view>): Likewise.
(views::__detail::__can_subrange): Replace with ...
(views::__detail::__can_owning_view): ... this.
(views::_All::_S_noexcept): Sync with operator().
(views::_All::operator()): Use owning_view instead of subrange
as per P2415R2.
* include/std/version (__cpp_lib_ranges): Adjust value.
* testsuite/std/ranges/adaptors/all.cc (test06): Adjust now that
views::all uses owning_view instead of subrange.
(test08): New test.
* testsuite/std/ranges/adaptors/lazy_split.cc (test09): Adjust
now that rvalue non-view non-borrowed ranges are viewable.
* testsuite/std/ranges/adaptors/split.cc (test06): Likewise.
Diff:
---
libstdc++-v3/include/bits/ranges_base.h | 16 +++-
libstdc++-v3/include/bits/ranges_cmp.h | 2 +-
libstdc++-v3/include/std/ranges | 89 +++++++++++++++++++++-
libstdc++-v3/include/std/version | 2 +-
libstdc++-v3/testsuite/std/ranges/adaptors/all.cc | 59 +++++++++-----
.../testsuite/std/ranges/adaptors/lazy_split.cc | 13 +++-
.../testsuite/std/ranges/adaptors/split.cc | 13 +++-
7 files changed, 159 insertions(+), 35 deletions(-)
diff --git a/libstdc++-v3/include/bits/ranges_base.h b/libstdc++-v3/include/bits/ranges_base.h
index 3c5f4b1790a..38db33fd2ce 100644
--- a/libstdc++-v3/include/bits/ranges_base.h
+++ b/libstdc++-v3/include/bits/ranges_base.h
@@ -634,7 +634,7 @@ namespace ranges
template<typename _Tp>
concept __is_derived_from_view_interface
= requires (_Tp __t) { __is_derived_from_view_interface_fn(__t, __t); };
- }
+ } // namespace __detail
/// [range.view] The ranges::view_base type.
struct view_base { };
@@ -689,11 +689,23 @@ namespace ranges
concept common_range
= range<_Tp> && same_as<iterator_t<_Tp>, sentinel_t<_Tp>>;
+ namespace __detail
+ {
+ template<typename _Tp>
+ inline constexpr bool __is_initializer_list = false;
+
+ template<typename _Tp>
+ inline constexpr bool __is_initializer_list<initializer_list<_Tp>> = true;
+ } // namespace __detail
+
/// A range which can be safely converted to a view.
template<typename _Tp>
concept viewable_range = range<_Tp>
&& ((view<remove_cvref_t<_Tp>> && constructible_from<remove_cvref_t<_Tp>, _Tp>)
- || (!view<remove_cvref_t<_Tp>> && borrowed_range<_Tp>));
+ || (!view<remove_cvref_t<_Tp>>
+ && (is_lvalue_reference_v<_Tp>
+ || (movable<remove_reference_t<_Tp>>
+ && !__detail::__is_initializer_list<remove_cvref_t<_Tp>>))));
// [range.iter.ops] range iterator operations
diff --git a/libstdc++-v3/include/bits/ranges_cmp.h b/libstdc++-v3/include/bits/ranges_cmp.h
index c84fb2ac0a2..6a5ad3de6e7 100644
--- a/libstdc++-v3/include/bits/ranges_cmp.h
+++ b/libstdc++-v3/include/bits/ranges_cmp.h
@@ -57,7 +57,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#ifdef __cpp_lib_concepts
// Define this here, included by all the headers that need to define it.
-#define __cpp_lib_ranges 202106L
+#define __cpp_lib_ranges 202110L
namespace ranges
{
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index ac85907f129..3e71ecb32b7 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -1144,6 +1144,87 @@ namespace views::__adaptor
template<typename _Tp>
inline constexpr bool enable_borrowed_range<ref_view<_Tp>> = true;
+ template<range _Range>
+ requires movable<_Range>
+ && (!__detail::__is_initializer_list<remove_cv_t<_Range>>)
+ class owning_view : public view_interface<owning_view<_Range>>
+ {
+ private:
+ _Range _M_r = _Range();
+
+ public:
+ owning_view() requires default_initializable<_Range> = default;
+
+ constexpr
+ owning_view(_Range&& __t)
+ noexcept(is_nothrow_move_constructible_v<_Range>)
+ : _M_r(std::move(__t))
+ { }
+
+ owning_view(owning_view&&) = default;
+ owning_view& operator=(owning_view&&) = default;
+
+ constexpr _Range&
+ base() & noexcept
+ { return _M_r; }
+
+ constexpr const _Range&
+ base() const& noexcept
+ { return _M_r; }
+
+ constexpr _Range&&
+ base() && noexcept
+ { return std::move(_M_r); }
+
+ constexpr const _Range&&
+ base() const&& noexcept
+ { return std::move(_M_r); }
+
+ constexpr iterator_t<_Range>
+ begin()
+ { return ranges::begin(_M_r); }
+
+ constexpr sentinel_t<_Range>
+ end()
+ { return ranges::end(_M_r); }
+
+ constexpr auto
+ begin() const requires range<const _Range>
+ { return ranges::begin(_M_r); }
+
+ constexpr auto
+ end() const requires range<const _Range>
+ { return ranges::end(_M_r); }
+
+ constexpr bool
+ empty() requires requires { ranges::empty(_M_r); }
+ { return ranges::empty(_M_r); }
+
+ constexpr bool
+ empty() const requires requires { ranges::empty(_M_r); }
+ { return ranges::empty(_M_r); }
+
+ constexpr auto
+ size() requires sized_range<_Range>
+ { return ranges::size(_M_r); }
+
+ constexpr auto
+ size() const requires sized_range<const _Range>
+ { return ranges::size(_M_r); }
+
+ constexpr auto
+ data() requires contiguous_range<_Range>
+ { return ranges::data(_M_r); }
+
+ constexpr auto
+ data() const requires contiguous_range<const _Range>
+ { return ranges::data(_M_r); }
+ };
+
+ template<typename _Tp>
+ inline constexpr bool enable_borrowed_range<owning_view<_Tp>>
+ = enable_borrowed_range<_Tp>;
+
namespace views
{
namespace __detail
@@ -1152,7 +1233,7 @@ namespace views::__adaptor
concept __can_ref_view = requires { ref_view{std::declval<_Range>()}; };
template<typename _Range>
- concept __can_subrange = requires { subrange{std::declval<_Range>()}; };
+ concept __can_owning_view = requires { owning_view{std::declval<_Range>()}; };
} // namespace __detail
struct _All : __adaptor::_RangeAdaptorClosure
@@ -1166,13 +1247,13 @@ namespace views::__adaptor
else if constexpr (__detail::__can_ref_view<_Range>)
return true;
else
- return noexcept(subrange{std::declval<_Range>()});
+ return noexcept(owning_view{std::declval<_Range>()});
}
template<viewable_range _Range>
requires view<decay_t<_Range>>
|| __detail::__can_ref_view<_Range>
- || __detail::__can_subrange<_Range>
+ || __detail::__can_owning_view<_Range>
constexpr auto
operator() [[nodiscard]] (_Range&& __r) const
noexcept(_S_noexcept<_Range>())
@@ -1182,7 +1263,7 @@ namespace views::__adaptor
else if constexpr (__detail::__can_ref_view<_Range>)
return ref_view{std::forward<_Range>(__r)};
else
- return subrange{std::forward<_Range>(__r)};
+ return owning_view{std::forward<_Range>(__r)};
}
static constexpr bool _S_has_simple_call_op = true;
diff --git a/libstdc++-v3/include/std/version b/libstdc++-v3/include/std/version
index 24311ee05c8..461e65b5fab 100644
--- a/libstdc++-v3/include/std/version
+++ b/libstdc++-v3/include/std/version
@@ -273,7 +273,7 @@
#define __cpp_lib_optional 202106L
#define __cpp_lib_polymorphic_allocator 201902L
#if __cpp_lib_concepts
-# define __cpp_lib_ranges 202106L
+# define __cpp_lib_ranges 202110L
#endif
#if __cpp_lib_atomic_wait || _GLIBCXX_HAVE_POSIX_SEMAPHORE
# define __cpp_lib_semaphore 201907L
diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/all.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/all.cc
index c25d972274f..e457462825d 100644
--- a/libstdc++-v3/testsuite/std/ranges/adaptors/all.cc
+++ b/libstdc++-v3/testsuite/std/ranges/adaptors/all.cc
@@ -19,7 +19,9 @@
// { dg-do run { target c++2a } }
#include <algorithm>
+#include <array>
#include <ranges>
+#include <vector>
#include <testsuite_hooks.h>
#include <testsuite_iterators.h>
@@ -130,20 +132,6 @@ test05()
static_assert(!requires { 0 | all; });
}
-template<bool B1, bool B2>
-struct BorrowedRange
-{
- int* ptr = nullptr;
-
- BorrowedRange(int (&arr)[3]) noexcept : ptr(arr) { }
-
- int* begin() const noexcept(B1) { return ptr; }
- int* end() const noexcept(B2) { return ptr + 3; }
-};
-
-template<bool B1, bool B2>
-const bool std::ranges::enable_borrowed_range<BorrowedRange<B1, B2>> = true;
-
void
test06()
{
@@ -152,11 +140,11 @@ test06()
// Using ref_view:
static_assert(noexcept(views::all(x)));
- // Using subrange:
- static_assert(noexcept(views::all(BorrowedRange<true, true>(x))));
- static_assert(!noexcept(views::all(BorrowedRange<true, false>(x))));
- static_assert(!noexcept(views::all(BorrowedRange<false, true>(x))));
- static_assert(!noexcept(views::all(BorrowedRange<false, false>(x))));
+ // Using owning_view:
+ static_assert(noexcept(views::all(std::array<int, 3>{})));
+ struct A { A(); A(const A&); };
+ static_assert(!std::is_nothrow_move_constructible_v<std::array<A, 3>>);
+ static_assert(!noexcept(views::all(std::array<A, 3>{})));
}
void
@@ -173,6 +161,38 @@ test07()
static_assert(!ranges::viewable_range<view_t&>);
}
+constexpr bool
+test08()
+{
+ // Verify P2415R2 "What is a view?" changes.
+ // In particular, rvalue non-view non-borrowed ranges are now viewable.
+ static_assert(ranges::viewable_range<std::vector<int>&&>);
+ static_assert(!ranges::viewable_range<const std::vector<int>&&>);
+
+ static_assert(ranges::viewable_range<std::initializer_list<int>&>);
+ static_assert(ranges::viewable_range<const std::initializer_list<int>&>);
+ static_assert(!ranges::viewable_range<std::initializer_list<int>&&>);
+ static_assert(!ranges::viewable_range<const std::initializer_list<int>&&>);
+
+ using type = views::all_t<std::vector<int>&&>;
+ using type = ranges::owning_view<std::vector<int>>;
+
+ std::same_as<type> auto v = std::vector<int>{{1,2,3}} | views::all;
+
+ VERIFY( ranges::equal(v, (int[]){1,2,3}) );
+ VERIFY( ranges::size(v) == 3 );
+ VERIFY( !ranges::empty(v) );
+ VERIFY( ranges::data(v) == &v[0] );
+
+ const auto w = std::move(v);
+ VERIFY( ranges::equal(w, (int[]){1,2,3}) );
+ VERIFY( ranges::size(w) == 3 );
+ VERIFY( !ranges::empty(w) );
+ VERIFY( ranges::data(w) == &w[0] );
+
+ return true;
+}
+
int
main()
{
@@ -183,4 +203,5 @@ main()
test05();
test06();
test07();
+ static_assert(test08());
}
diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/lazy_split.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/lazy_split.cc
index a7d3dd6a23e..e46f76d7632 100644
--- a/libstdc++-v3/testsuite/std/ranges/adaptors/lazy_split.cc
+++ b/libstdc++-v3/testsuite/std/ranges/adaptors/lazy_split.cc
@@ -163,10 +163,15 @@ test09()
static_assert(!requires { lazy_split(p)(); });
static_assert(!requires { s | lazy_split; });
- static_assert(!requires { s | lazy_split(p); });
- static_assert(!requires { lazy_split(p)(s); });
- static_assert(!requires { s | (lazy_split(p) | views::all); });
- static_assert(!requires { (lazy_split(p) | views::all)(s); });
+ // Test the case where the closure object is used as an rvalue and therefore
+ // the copy of p is forwarded as an rvalue.
+ // This used to be invalid, but is now well-formed after P2415R2 relaxed
+ // the requirements of viewable_range to admit rvalue non-view non-borrowed
+ // ranges such as std::string&&.
+ static_assert(requires { s | lazy_split(p); });
+ static_assert(requires { lazy_split(p)(s); });
+ static_assert(requires { s | (lazy_split(p) | views::all); });
+ static_assert(requires { (lazy_split(p) | views::all)(s); });
static_assert(requires { s | lazy_split(views::all(p)); });
static_assert(requires { lazy_split(views::all(p))(s); });
diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/split.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/split.cc
index 44245f5071a..ca10608efb5 100644
--- a/libstdc++-v3/testsuite/std/ranges/adaptors/split.cc
+++ b/libstdc++-v3/testsuite/std/ranges/adaptors/split.cc
@@ -145,10 +145,15 @@ test06()
static_assert(!requires { split(p)(); });
static_assert(!requires { s | split; });
- static_assert(!requires { s | split(p); });
- static_assert(!requires { split(p)(s); });
- static_assert(!requires { s | (split(p) | views::all); });
- static_assert(!requires { (split(p) | views::all)(s); });
+ // Test the case where the closure object is used as an rvalue and therefore
+ // the copy of p is forwarded as an rvalue.
+ // This used to be invalid, but is now well-formed after P2415R2 relaxed
+ // the requirements of viewable_range to admit rvalue non-view non-borrowed
+ // ranges such as std::string&&.
+ static_assert(requires { s | split(p); });
+ static_assert(requires { split(p)(s); });
+ static_assert(requires { s | (split(p) | views::all); });
+ static_assert(requires { (split(p) | views::all)(s); });
static_assert(requires { s | split(views::all(p)); });
static_assert(requires { split(views::all(p))(s); });
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