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libstdc++: P1983R0 Wording for GB301, US296, US292, US291, and US283

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Among other changes, P1983R0 resolves LWG 3278 in a different way, so this patch
also reverts the already-applied wording 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 needed so
that _Iterator's converting constructor can 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.
This commit is contained in:
Patrick Palka 2020-02-18 12:31:25 -05:00
parent 6fa35f0e28
commit 242b4fb7f4
3 changed files with 29 additions and 7 deletions
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16
libstdc++-v3/ChangeLog
View file

@ -1,3 +1,19 @@
2020-02-18 Patrick Palka <ppalka@redhat.com>
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.
2020-02-18 Jonathan Wakely <jwakely@redhat.com>
PR libstdc++/93818

18
libstdc++-v3/include/std/ranges
View file

@ -1488,6 +1488,10 @@ namespace views
base() &&
{ return std::move(_M_base); }
constexpr const _Pred&
pred() const
{ return *_M_pred; }
constexpr _Iterator
begin()
{
@ -2336,8 +2340,6 @@ 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, _Outer_iter __outer)
: _M_outer(std::move(__outer)),
@ -2437,6 +2439,7 @@ 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>;
};
@ -2475,8 +2478,7 @@ 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;
@ -2509,8 +2511,10 @@ 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
@ -2676,7 +2680,7 @@ 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))
{ }

2
libstdc++-v3/testsuite/std/ranges/adaptors/filter.cc
View file

@ -46,6 +46,8 @@ 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