This patch also reverts the r11-3504 workaround since it's made obsolete
by this resolution.
Tested on x86_64-pc-linux-gnu, does this look OK for trunk only?
libstdc++-v3/ChangeLog:
* include/bits/ranges_base.h (view_interface): Forward declare.
(__detail::__is_derived_from_view_interface_fn): Declare
(__detail::__is_derived_from_view_interface): Define as per LWG 3549.
(enable_view): Adjust as per LWG 3549.
* include/bits/ranges_util.h (view_interface): Don't derive from
view_base.
* include/std/ranges (filter_view): Revert r11-3504 change.
(transform_view): Likewise.
(take_view): Likewise.
(take_while_view): Likewise.
(drop_view): Likewise.
(drop_while_view): Likewise.
(join_view): Likewise.
(split_view): Likewise.
(reverse_view): Likewise.
* testsuite/std/ranges/adaptors/sizeof.cc: Update expected
sizes.
* testsuite/std/ranges/view.cc (test_view::test_view): Remove
now that views no longer need to be default-initializable.
(test01): New test.
---
libstdc++-v3/include/bits/ranges_base.h | 21 ++++++++-
libstdc++-v3/include/bits/ranges_util.h | 2 +-
libstdc++-v3/include/std/ranges | 45 +++++++++----------
.../testsuite/std/ranges/adaptors/sizeof.cc | 6 +--
libstdc++-v3/testsuite/std/ranges/view.cc | 28 ++++++++++--
5 files changed, 70 insertions(+), 32 deletions(-)
diff --git a/libstdc++-v3/include/bits/ranges_base.h
b/libstdc++-v3/include/bits/ranges_base.h
index 01d0c35f4b4..7801b2fd023 100644
--- a/libstdc++-v3/include/bits/ranges_base.h
+++ b/libstdc++-v3/include/bits/ranges_base.h
@@ -614,12 +614,31 @@ namespace ranges
template<sized_range _Range>
using range_size_t = decltype(ranges::size(std::declval<_Range&>()));
+ template<typename _Derived>
+ requires is_class_v<_Derived> && same_as<_Derived, remove_cv_t<_Derived>>
+ class view_interface; // defined in <bits/ranges_util.h>
+
+ namespace __detail
+ {
+ template<typename _Tp, typename _Up>
+ requires (!same_as<_Tp, view_interface<_Up>>)
+ void __is_derived_from_view_interface_fn(const _Tp&,
+ const view_interface<_Up>&); //
not defined
+
+ // Returns true iff _Tp has exactly one public base class that's a
+ // specialization of view_interface.
+ template<typename _Tp>
+ concept __is_derived_from_view_interface
+ = requires (_Tp __t) { __is_derived_from_view_interface_fn(__t, __t); };
+ }
+
/// [range.view] The ranges::view_base type.
struct view_base { };
/// [range.view] The ranges::enable_view boolean.
template<typename _Tp>
- inline constexpr bool enable_view = derived_from<_Tp, view_base>;
+ inline constexpr bool enable_view = derived_from<_Tp, view_base>
+ || __detail::__is_derived_from_view_interface<_Tp>;
/// [range.view] The ranges::view concept.
template<typename _Tp>
diff --git a/libstdc++-v3/include/bits/ranges_util.h
b/libstdc++-v3/include/bits/ranges_util.h
index 1afa66d298c..5c0bef26220 100644
--- a/libstdc++-v3/include/bits/ranges_util.h
+++ b/libstdc++-v3/include/bits/ranges_util.h
@@ -61,7 +61,7 @@ namespace ranges
/// The ranges::view_interface class template
template<typename _Derived>
requires is_class_v<_Derived> && same_as<_Derived, remove_cv_t<_Derived>>
- class view_interface : public view_base
+ class view_interface
{
private:
constexpr _Derived& _M_derived() noexcept
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index 64396027c1b..e47fc075bbe 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -1533,9 +1533,9 @@ namespace views::__adaptor
{ return __y.__equal(__x); }
};
+ _Vp _M_base = _Vp();
[[no_unique_address]] __detail::__box<_Pred> _M_pred;
[[no_unique_address]] __detail::_CachedPosition<_Vp> _M_cached_begin;
- _Vp _M_base = _Vp();
public:
filter_view() requires (default_initializable<_Vp>
@@ -1544,7 +1544,7 @@ namespace views::__adaptor
constexpr
filter_view(_Vp __base, _Pred __pred)
- : _M_pred(std::move(__pred)), _M_base(std::move(__base))
+ : _M_base(std::move(__base)), _M_pred(std::move(__pred))
{ }
constexpr _Vp
@@ -1900,8 +1900,8 @@ namespace views::__adaptor
friend _Sentinel<!_Const>;
};
- [[no_unique_address]] __detail::__box<_Fp> _M_fun;
_Vp _M_base = _Vp();
+ [[no_unique_address]] __detail::__box<_Fp> _M_fun;
public:
transform_view() requires (default_initializable<_Vp>
@@ -1910,7 +1910,7 @@ namespace views::__adaptor
constexpr
transform_view(_Vp __base, _Fp __fun)
- : _M_fun(std::move(__fun)), _M_base(std::move(__base))
+ : _M_base(std::move(__base)), _M_fun(std::move(__fun))
{ }
constexpr _Vp
@@ -2037,15 +2037,15 @@ namespace views::__adaptor
friend _Sentinel<!_Const>;
};
- range_difference_t<_Vp> _M_count = 0;
_Vp _M_base = _Vp();
+ range_difference_t<_Vp> _M_count = 0;
public:
take_view() requires default_initializable<_Vp> = default;
constexpr
take_view(_Vp base, range_difference_t<_Vp> __count)
- : _M_count(std::move(__count)), _M_base(std::move(base))
+ : _M_base(std::move(base)), _M_count(std::move(__count))
{ }
constexpr _Vp
@@ -2268,8 +2268,8 @@ namespace views::__adaptor
friend _Sentinel<!_Const>;
};
- [[no_unique_address]] __detail::__box<_Pred> _M_pred;
_Vp _M_base = _Vp();
+ [[no_unique_address]] __detail::__box<_Pred> _M_pred;
public:
take_while_view() requires (default_initializable<_Vp>
@@ -2278,7 +2278,7 @@ namespace views::__adaptor
constexpr
take_while_view(_Vp base, _Pred __pred)
- : _M_pred(std::move(__pred)), _M_base(std::move(base))
+ : _M_base(std::move(base)), _M_pred(std::move(__pred))
{ }
constexpr _Vp
@@ -2349,8 +2349,8 @@ namespace views::__adaptor
class drop_view : public view_interface<drop_view<_Vp>>
{
private:
- range_difference_t<_Vp> _M_count = 0;
_Vp _M_base = _Vp();
+ range_difference_t<_Vp> _M_count = 0;
// ranges::next(begin(base), count, end(base)) is O(1) if _Vp satisfies
// both random_access_range and sized_range. Otherwise, cache its result.
@@ -2366,7 +2366,7 @@ namespace views::__adaptor
constexpr
drop_view(_Vp __base, range_difference_t<_Vp> __count)
- : _M_count(__count), _M_base(std::move(__base))
+ : _M_base(std::move(__base)), _M_count(__count)
{ __glibcxx_assert(__count >= 0); }
constexpr _Vp
@@ -2503,9 +2503,9 @@ namespace views::__adaptor
class drop_while_view : public view_interface<drop_while_view<_Vp, _Pred>>
{
private:
+ _Vp _M_base = _Vp();
[[no_unique_address]] __detail::__box<_Pred> _M_pred;
[[no_unique_address]] __detail::_CachedPosition<_Vp> _M_cached_begin;
- _Vp _M_base = _Vp();
public:
drop_while_view() requires (default_initializable<_Vp>
@@ -2514,7 +2514,7 @@ namespace views::__adaptor
constexpr
drop_while_view(_Vp __base, _Pred __pred)
- : _M_pred(std::move(__pred)), _M_base(std::move(__base))
+ : _M_base(std::move(__base)), _M_pred(std::move(__pred))
{ }
constexpr _Vp
@@ -2850,9 +2850,9 @@ namespace views::__adaptor
friend _Sentinel<!_Const>;
};
+ _Vp _M_base = _Vp();
[[no_unique_address]]
__detail::__non_propagating_cache<remove_cv_t<_InnerRange>> _M_inner;
- _Vp _M_base = _Vp();
public:
join_view() requires default_initializable<_Vp> = default;
@@ -3288,12 +3288,12 @@ namespace views::__adaptor
{ ranges::iter_swap(__x._M_i_current(), __y._M_i_current()); }
};
+ _Vp _M_base = _Vp();
_Pattern _M_pattern = _Pattern();
// XXX: _M_current is "present only if !forward_range<V>"
[[no_unique_address]]
__detail::__maybe_present_t<!forward_range<_Vp>,
__detail::__non_propagating_cache<iterator_t<_Vp>>> _M_current;
- _Vp _M_base = _Vp();
public:
@@ -3303,7 +3303,7 @@ namespace views::__adaptor
constexpr
lazy_split_view(_Vp __base, _Pattern __pattern)
- : _M_pattern(std::move(__pattern)), _M_base(std::move(__base))
+ : _M_base(std::move(__base)), _M_pattern(std::move(__pattern))
{ }
template<input_range _Range>
@@ -3311,8 +3311,8 @@ namespace views::__adaptor
&& constructible_from<_Pattern, single_view<range_value_t<_Range>>>
constexpr
lazy_split_view(_Range&& __r, range_value_t<_Range> __e)
- : _M_pattern(views::single(std::move(__e))),
- _M_base(views::all(std::forward<_Range>(__r)))
+ : _M_base(views::all(std::forward<_Range>(__r))),
+ _M_pattern(views::single(std::move(__e)))
{ }
constexpr _Vp
@@ -3410,9 +3410,9 @@ namespace views::__adaptor
class split_view : public view_interface<split_view<_Vp, _Pattern>>
{
private:
+ _Vp _M_base = _Vp();
_Pattern _M_pattern = _Pattern();
__detail::__non_propagating_cache<subrange<iterator_t<_Vp>>>
_M_cached_begin;
- _Vp _M_base = _Vp();
struct _Iterator;
struct _Sentinel;
@@ -3424,8 +3424,7 @@ namespace views::__adaptor
constexpr
split_view(_Vp __base, _Pattern __pattern)
- : _M_pattern(std::move(__pattern)),
- _M_base(std::move(__base))
+ : _M_base(std::move(__base)), _M_pattern(std::move(__pattern))
{ }
template<forward_range _Range>
@@ -3433,8 +3432,8 @@ namespace views::__adaptor
&& constructible_from<_Pattern, single_view<range_value_t<_Range>>>
constexpr
split_view(_Range&& __r, range_value_t<_Range> __e)
- : _M_pattern(views::single(std::move(__e))),
- _M_base(views::all(std::forward<_Range>(__r)))
+ : _M_base(views::all(std::forward<_Range>(__r))),
+ _M_pattern(views::single(std::move(__e)))
{ }
constexpr _Vp
@@ -3759,11 +3758,11 @@ namespace views::__adaptor
&& sized_sentinel_for<sentinel_t<_Vp>,
iterator_t<_Vp>>);
+ _Vp _M_base = _Vp();
[[no_unique_address]]
__detail::__maybe_present_t<_S_needs_cached_begin,
__detail::_CachedPosition<_Vp>>
_M_cached_begin;
- _Vp _M_base = _Vp();
public:
reverse_view() requires default_initializable<_Vp> = default;
diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/sizeof.cc
b/libstdc++-v3/testsuite/std/ranges/adaptors/sizeof.cc
index 219e2a61f07..61524d4c0ad 100644
--- a/libstdc++-v3/testsuite/std/ranges/adaptors/sizeof.cc
+++ b/libstdc++-v3/testsuite/std/ranges/adaptors/sizeof.cc
@@ -42,11 +42,11 @@ static_assert(sizeof(ranges::drop_while_view<V,
decltype(&pred_f)>) == 4*ptr);
static_assert(sizeof(ranges::transform_view<V, decltype(&func_f)>) == 3*ptr);
static_assert(sizeof(ranges::filter_view<V, decltype(pred_l)>) == 3*ptr);
-static_assert(sizeof(ranges::take_while_view<V, decltype(pred_l)>) == 3*ptr);
+static_assert(sizeof(ranges::take_while_view<V, decltype(pred_l)>) == 2*ptr);
static_assert(sizeof(ranges::drop_while_view<V, decltype(pred_l)>) == 3*ptr);
-static_assert(sizeof(ranges::transform_view<V, decltype(func_l)>) == 3*ptr);
+static_assert(sizeof(ranges::transform_view<V, decltype(func_l)>) == 2*ptr);
static_assert(sizeof(ranges::lazy_split_view<V, std::string_view>) == 4*ptr);
static_assert
- (sizeof(ranges::reverse_view<ranges::filter_view<V, decltype(pred_l)>>) ==
4*ptr);
+ (sizeof(ranges::reverse_view<ranges::filter_view<V, decltype(pred_l)>>) ==
3*ptr);
diff --git a/libstdc++-v3/testsuite/std/ranges/view.cc
b/libstdc++-v3/testsuite/std/ranges/view.cc
index dd8258220ed..98a162ec866 100644
--- a/libstdc++-v3/testsuite/std/ranges/view.cc
+++ b/libstdc++-v3/testsuite/std/ranges/view.cc
@@ -52,10 +52,7 @@
static_assert(!std::ranges::view<__gnu_test::test_random_access_range<int>>);
template<typename T>
struct test_view
: __gnu_test::test_random_access_range<T>, std::ranges::view_base
-{
- // views must be default-initializable:
- test_view() : __gnu_test::test_random_access_range<T>(nullptr, nullptr) { }
-};
+{ };
static_assert(std::ranges::view<test_view<int>>);
@@ -63,3 +60,26 @@ template<>
constexpr bool std::ranges::enable_view<test_view<long>> = false;
static_assert(!std::ranges::view<test_view<long>>);
+
+void
+test01()
+{
+ // Verify LWG 3549 changes to ranges::enable_view.
+ using std::ranges::view_interface;
+
+ struct v1
+ : __gnu_test::test_random_access_range<int>, view_interface<v1> { };
+ static_assert(!std::derived_from<v1, std::ranges::view_base>);
+ static_assert(std::ranges::enable_view<v1>);
+
+ struct v2 : v1, view_interface<v2> { };
+ static_assert(!std::derived_from<v2, std::ranges::view_base>);
+ static_assert(!std::ranges::enable_view<v2>);
+
+ struct v3 : __gnu_test::test_random_access_range<int> { };
+ static_assert(!std::derived_from<v3, std::ranges::view_base>);
+ static_assert(!std::ranges::enable_view<v3>);
+
+ struct v4 { };
+ static_assert(!std::ranges::enable_view<view_interface<v4>>);
+}
--
2.33.1.711.g9d530dc002
