On Tue, 18 Feb 2020, Patrick Palka wrote:
> Among other changes, P1983R0 resolves LWG 3278 in a different way, so this
> patch
> also reverts the already-applied change of LWG 3278.
>
> The wording for US283 has already been applied it seems.
>
> libstdc++-v3/ChangeLog:
>
> P1983R0 Wording for GB301, US296, US292, US291, and US283
> * include/std/ranges (filter_view::pred): New member function.
> (join_view::_Iterator::_Iterator): Remove now-redundant comment since
> P1983R0 fixes the highlighted issue in the same way.
> (join_view::_M_inner): Remove mutable specifier, effectively reverting
> the proposed wording changes of P3278.
> (join_view::begin): Refine the condition for when to return a const
> iterator.
> (split_view::_OuterIter::_OuterIter): Adjust constraints.
> * testsuite/std/ranges/adaptors/filter.cc: Test that filter_view::pred
> exists and works.
Oops, this patch is incomplete, it breaks the join_view adaptor test due
to a missing friend, sorry about that. Here's the complete and tested
patch:
-- >8 --
Subject: [PATCH] libstdc++: P1983R0 Wording for GB301, US296, US292, US291,
and US283
Among other changes, P1983R0 resolves LWG 3278 in a different way, so this patch
also reverts the already-applied change of LWG 3278.
The wording for US291 (the join_view::begin hunk) also required adding the
friend _Iterator<!_Const> to join::view::_Iterator. This friend is required for
one of this iterator's converting constructors to be able to access the private
members of an _Iterator of the opposite constness.
The wording for US283 has already been applied it seems.
libstdc++-v3/ChangeLog:
P1983R0 Wording for GB301, US296, US292, US291, and US283
* include/std/ranges (filter_view::pred): New member function.
(join_view::_Iterator::_Iterator): Remove now-redundant comment since
P1983R0 fixes the highlighted issue in the same way.
(join_view::_Iterator<_Const>): Add friend
join_view::_Iterator<!_Const>.
(join_view::_M_inner): Remove mutable specifier, effectively reverting
the proposed wording changes of P3278.
(join_view::begin): Refine the condition for when to return a const
iterator.
(split_view::_OuterIter::_OuterIter): Adjust constraints.
* testsuite/std/ranges/adaptors/filter.cc: Test that filter_view::pred
exists and works.
---
libstdc++-v3/include/std/ranges | 18 +++++++++++-------
.../testsuite/std/ranges/adaptors/filter.cc | 2 ++
2 files changed, 13 insertions(+), 7 deletions(-)
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index a04387a75c4..fb6e67dd0b3 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -1556,6 +1556,10 @@ namespace views
base() &&
{ return std::move(_M_base); }
+ constexpr const _Pred&
+ pred() const
+ { return *_M_pred; }
+
constexpr _Iterator
begin()
{
@@ -2421,8 +2425,6 @@ namespace views
_Iterator() = default;
- // XXX: had to change the type of __outer from iterator_t<_Vp> to
- // iterator_t<_Base> here, a possible defect in the spec?
constexpr
_Iterator(_Parent& __parent, iterator_t<_Base> __outer)
: _M_outer(std::move(__outer)),
@@ -2523,6 +2525,7 @@ namespace views
noexcept(noexcept(ranges::iter_swap(__x._M_inner, __y._M_inner)))
{ return ranges::iter_swap(__x._M_inner, __y._M_inner); }
+ friend _Iterator<!_Const>;
friend _Sentinel<_Const>;
};
@@ -2561,8 +2564,7 @@ namespace views
_Vp _M_base = _Vp();
// XXX: _M_inner is "present only when !is_reference_v<_InnerRange>"
- // Applied P3278 and made this field mutable.
- [[no_unique_address]] mutable
+ [[no_unique_address]]
conditional_t<!is_reference_v<_InnerRange>,
all_view<_InnerRange>, __detail::_Empty> _M_inner;
@@ -2595,8 +2597,10 @@ namespace views
constexpr auto
begin()
{
- return _Iterator<__detail::__simple_view<_Vp>>{*this,
- ranges::begin(_M_base)};
+ constexpr bool __use_const
+ = (__detail::__simple_view<_Vp>
+ && is_reference_v<range_reference_t<_Vp>>);
+ return _Iterator<__use_const>{*this, ranges::begin(_M_base)};
}
constexpr auto
@@ -2762,7 +2766,7 @@ namespace views
constexpr
_OuterIter(_OuterIter<!_Const> __i)
requires _Const
- && convertible_to<iterator_t<_Vp>, iterator_t<const _Vp>>
+ && convertible_to<iterator_t<_Vp>, iterator_t<_Base>>
: _M_parent(__i._M_parent), _M_current(std::move(__i._M_current))
{ }
diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/filter.cc
b/libstdc++-v3/testsuite/std/ranges/adaptors/filter.cc
index 834d10f7f91..84858798dda 100644
--- a/libstdc++-v3/testsuite/std/ranges/adaptors/filter.cc
+++ b/libstdc++-v3/testsuite/std/ranges/adaptors/filter.cc
@@ -48,6 +48,8 @@ test01()
static_assert(ranges::range<ranges::all_view<R>>);
VERIFY( ranges::equal(v, (int[]){1,3,5}) );
VERIFY( ranges::equal(v | views::reverse, (int[]){5,3,1}) );
+ VERIFY( v.pred()(3) == true );
+ VERIFY( v.pred()(4) == false );
}
void
--
2.25.1.291.ge68e29171c
