On 05/08/21 15:40 +0100, Jonathan Wakely wrote:
On 05/08/21 15:19 +0100, Jonathan Wakely wrote:
On 04/08/21 12:55 +0100, Jonathan Wakely wrote:
This adds [[nodiscard]] throughout <iterator>, as proposed by P2377R0
(with some minor corrections).
The attribute is added for all modes from C++11 up, using
[[__nodiscard__]] or _GLIBCXX_NODISCARD where C++17 [[nodiscard]] can't
be used directly.
This change causes errors when -fconcepts-ts is used. Fixed like so.
Tested powerpc64le-linux, committed to trunk.
commit 7b1de3eb9ed3f8dde54732d88520292c5ad1157d
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Thu Aug 5 13:34:00 2021
libstdc++: Move attributes that follow requires-clauses [PR101782]
As explained in the PR, the grammar in the Concepts TS means that a [
token following a requires-clause is parsed as part of the
logical-or-expression rather than the start of an attribute. That makes
the following ill-formed when using -fconcepts-ts:
template<typename T> requires foo<T> [[nodiscard]] int f(T);
This change moves all attributes that follow a requires-clause to the
end of the function declarator.
Except that as Jakub pointed out, putting it there doesn't work.
It needs to be:
template<typename T> requires foo<T> int f [[nodiscard]] (T);
At least the testsuite isn't failing now, but the attributes I moved
have no effect. I'll fix it ... some time.
This should be correct now.
Tested powerpc64le-linux, pushed to trunk.
commit c8b024fa4b76bfd914e96dd3cecfbb6ee8e91316
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Thu Aug 5 16:46:00 2021
libstdc++: Move [[nodiscard]] attributes again [PR101782]
Where I moved these nodiscard attributes to made them apply to the
function type, not to the function. This meant they no longer generated
the desired -Wunused-result warnings, and were ill-formed with Clang
(but only a pedwarn with GCC).
Clang also detected ill-formed attributes in <queue> which this fixes.
Signed-off-by: Jonathan Wakely <jwak...@redhat.com>
libstdc++-v3/ChangeLog:
PR libstdc++/101782
* include/bits/ranges_base.h (ranges::begin, ranges::end)
(ranges::rbegin, ranges::rend, ranges::size, ranges::ssize)
(ranges::empty, ranges::data): Move attribute after the
declarator-id instead of at the end of the declarator.
* include/bits/stl_iterator.h (__gnu_cxx::__normal_iterator):
Move attributes back to the start of the function declarator,
but move the requires-clause to the end.
(common_iterator): Move attribute after the declarator-id.
* include/bits/stl_queue.h (queue): Remove ill-formed attributes
from friend declaration that are not definitions.
* include/std/ranges (views::all, views::filter)
(views::transform, views::take, views::take_while,
views::drop) (views::drop_while, views::join,
views::lazy_split) (views::split, views::counted,
views::common, views::reverse) (views::elements): Move
attributes after the declarator-id.
diff --git a/libstdc++-v3/include/bits/ranges_base.h b/libstdc++-v3/include/bits/ranges_base.h
index 1dac9680b4f..49c7d9c9f06 100644
--- a/libstdc++-v3/include/bits/ranges_base.h
+++ b/libstdc++-v3/include/bits/ranges_base.h
@@ -111,8 +111,7 @@ namespace ranges
requires is_array_v<remove_reference_t<_Tp>> || __member_begin<_Tp>
|| __adl_begin<_Tp>
constexpr auto
- operator()(_Tp&& __t) const noexcept(_S_noexcept<_Tp&>())
- [[nodiscard]]
+ operator()[[nodiscard]](_Tp&& __t) const noexcept(_S_noexcept<_Tp&>())
{
if constexpr (is_array_v<remove_reference_t<_Tp>>)
{
@@ -163,8 +162,7 @@ namespace ranges
requires is_bounded_array_v<remove_reference_t<_Tp>>
|| __member_end<_Tp> || __adl_end<_Tp>
constexpr auto
- operator()(_Tp&& __t) const noexcept(_S_noexcept<_Tp&>())
- [[nodiscard]]
+ operator()[[nodiscard]](_Tp&& __t) const noexcept(_S_noexcept<_Tp&>())
{
if constexpr (is_bounded_array_v<remove_reference_t<_Tp>>)
{
@@ -268,9 +266,8 @@ namespace ranges
template<__maybe_borrowed_range _Tp>
requires __member_rbegin<_Tp> || __adl_rbegin<_Tp> || __reversable<_Tp>
constexpr auto
- operator()(_Tp&& __t) const
+ operator()[[nodiscard]](_Tp&& __t) const
noexcept(_S_noexcept<_Tp&>())
- [[nodiscard]]
{
if constexpr (__member_rbegin<_Tp>)
return __t.rbegin();
@@ -327,9 +324,8 @@ namespace ranges
template<__maybe_borrowed_range _Tp>
requires __member_rend<_Tp> || __adl_rend<_Tp> || __reversable<_Tp>
constexpr auto
- operator()(_Tp&& __t) const
+ operator()[[nodiscard]](_Tp&& __t) const
noexcept(_S_noexcept<_Tp&>())
- [[nodiscard]]
{
if constexpr (__member_rend<_Tp>)
return __t.rend();
@@ -417,8 +413,7 @@ namespace ranges
requires is_bounded_array_v<remove_reference_t<_Tp>>
|| __member_size<_Tp> || __adl_size<_Tp> || __sentinel_size<_Tp>
constexpr auto
- operator()(_Tp&& __t) const noexcept(_S_noexcept<_Tp&>())
- [[nodiscard]]
+ operator()[[nodiscard]](_Tp&& __t) const noexcept(_S_noexcept<_Tp&>())
{
if constexpr (is_bounded_array_v<remove_reference_t<_Tp>>)
return extent_v<remove_reference_t<_Tp>>;
@@ -438,8 +433,7 @@ namespace ranges
template<typename _Tp>
requires requires (_Tp& __t) { _Size{}(__t); }
constexpr auto
- operator()(_Tp&& __t) const noexcept(noexcept(_Size{}(__t)))
- [[nodiscard]]
+ operator()[[nodiscard]](_Tp&& __t) const noexcept(noexcept(_Size{}(__t)))
{
auto __size = _Size{}(__t);
using __size_type = decltype(__size);
@@ -498,8 +492,7 @@ namespace ranges
requires __member_empty<_Tp> || __size0_empty<_Tp>
|| __eq_iter_empty<_Tp>
constexpr bool
- operator()(_Tp&& __t) const noexcept(_S_noexcept<_Tp&>())
- [[nodiscard]]
+ operator()[[nodiscard]](_Tp&& __t) const noexcept(_S_noexcept<_Tp&>())
{
if constexpr (__member_empty<_Tp>)
return bool(__t.empty());
@@ -540,8 +533,7 @@ namespace ranges
template<__maybe_borrowed_range _Tp>
requires __member_data<_Tp> || __begin_data<_Tp>
constexpr auto
- operator()(_Tp&& __t) const noexcept(_S_noexcept<_Tp>())
- [[nodiscard]]
+ operator()[[nodiscard]](_Tp&& __t) const noexcept(_S_noexcept<_Tp>())
{
if constexpr (__member_data<_Tp>)
return __t.data();
diff --git a/libstdc++-v3/include/bits/stl_iterator.h b/libstdc++-v3/include/bits/stl_iterator.h
index 053ae41e9c3..c5b02408c1c 100644
--- a/libstdc++-v3/include/bits/stl_iterator.h
+++ b/libstdc++-v3/include/bits/stl_iterator.h
@@ -1118,21 +1118,22 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#if __cpp_lib_three_way_comparison
template<typename _IteratorL, typename _IteratorR, typename _Container>
- requires requires (_IteratorL __lhs, _IteratorR __rhs)
- { { __lhs == __rhs } -> std::convertible_to<bool>; }
+ [[nodiscard]]
constexpr bool
operator==(const __normal_iterator<_IteratorL, _Container>& __lhs,
const __normal_iterator<_IteratorR, _Container>& __rhs)
noexcept(noexcept(__lhs.base() == __rhs.base()))
- [[nodiscard]]
+ requires requires {
+ { __lhs.base() == __rhs.base() } -> std::convertible_to<bool>;
+ }
{ return __lhs.base() == __rhs.base(); }
template<typename _IteratorL, typename _IteratorR, typename _Container>
+ [[nodiscard]]
constexpr std::__detail::__synth3way_t<_IteratorR, _IteratorL>
operator<=>(const __normal_iterator<_IteratorL, _Container>& __lhs,
const __normal_iterator<_IteratorR, _Container>& __rhs)
noexcept(noexcept(std::__detail::__synth3way(__lhs.base(), __rhs.base())))
- [[nodiscard]]
{ return std::__detail::__synth3way(__lhs.base(), __rhs.base()); }
#else
// Forward iterator requirements
@@ -1985,9 +1986,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _It2, sentinel_for<_It> _Sent2>
requires sentinel_for<_Sent, _It2>
friend bool
- operator==(const common_iterator& __x,
- const common_iterator<_It2, _Sent2>& __y)
- [[nodiscard]]
+ operator== [[nodiscard]] (const common_iterator& __x,
+ const common_iterator<_It2, _Sent2>& __y)
{
switch(__x._M_index << 2 | __y._M_index)
{
@@ -2008,9 +2008,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _It2, sentinel_for<_It> _Sent2>
requires sentinel_for<_Sent, _It2> && equality_comparable_with<_It, _It2>
friend bool
- operator==(const common_iterator& __x,
- const common_iterator<_It2, _Sent2>& __y)
- [[nodiscard]]
+ operator== [[nodiscard]] (const common_iterator& __x,
+ const common_iterator<_It2, _Sent2>& __y)
{
switch(__x._M_index << 2 | __y._M_index)
{
@@ -2032,9 +2031,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<sized_sentinel_for<_It> _It2, sized_sentinel_for<_It> _Sent2>
requires sized_sentinel_for<_Sent, _It2>
friend iter_difference_t<_It2>
- operator-(const common_iterator& __x,
- const common_iterator<_It2, _Sent2>& __y)
- [[nodiscard]]
+ operator- [[nodiscard]] (const common_iterator& __x,
+ const common_iterator<_It2, _Sent2>& __y)
{
switch(__x._M_index << 2 | __y._M_index)
{
diff --git a/libstdc++-v3/include/bits/stl_queue.h b/libstdc++-v3/include/bits/stl_queue.h
index 363868fe0a6..41ffc50d380 100644
--- a/libstdc++-v3/include/bits/stl_queue.h
+++ b/libstdc++-v3/include/bits/stl_queue.h
@@ -107,18 +107,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#endif
template<typename _Tp1, typename _Seq1>
- _GLIBCXX_NODISCARD
friend bool
operator==(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
template<typename _Tp1, typename _Seq1>
- _GLIBCXX_NODISCARD
friend bool
operator<(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
#if __cpp_lib_three_way_comparison
template<typename _Tp1, three_way_comparable _Seq1>
- [[nodiscard]]
friend compare_three_way_result_t<_Seq1>
operator<=>(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
#endif
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index 71b7dc7d295..fb8905fab08 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -1127,9 +1127,8 @@ namespace views::__adaptor
|| __detail::__can_ref_view<_Range>
|| __detail::__can_subrange<_Range>
constexpr auto
- operator()(_Range&& __r) const
+ operator() [[nodiscard]] (_Range&& __r) const
noexcept(_S_noexcept<_Range>())
- [[nodiscard]]
{
if constexpr (view<decay_t<_Range>>)
return std::forward<_Range>(__r);
@@ -1554,8 +1553,7 @@ namespace views::__adaptor
template<viewable_range _Range, typename _Pred>
requires __detail::__can_filter_view<_Range, _Pred>
constexpr auto
- operator()(_Range&& __r, _Pred&& __p) const
- [[nodiscard]]
+ operator() [[nodiscard]] (_Range&& __r, _Pred&& __p) const
{
return filter_view(std::forward<_Range>(__r), std::forward<_Pred>(__p));
}
@@ -1932,8 +1930,7 @@ namespace views::__adaptor
template<viewable_range _Range, typename _Fp>
requires __detail::__can_transform_view<_Range, _Fp>
constexpr auto
- operator()(_Range&& __r, _Fp&& __f) const
- [[nodiscard]]
+ operator() [[nodiscard]] (_Range&& __r, _Fp&& __f) const
{
return transform_view(std::forward<_Range>(__r), std::forward<_Fp>(__f));
}
@@ -2114,8 +2111,7 @@ namespace views::__adaptor
template<viewable_range _Range, typename _Tp>
requires __detail::__can_take_view<_Range, _Tp>
constexpr auto
- operator()(_Range&& __r, _Tp&& __n) const
- [[nodiscard]]
+ operator() [[nodiscard]] (_Range&& __r, _Tp&& __n) const
{
return take_view(std::forward<_Range>(__r), std::forward<_Tp>(__n));
}
@@ -2242,8 +2238,7 @@ namespace views::__adaptor
template<viewable_range _Range, typename _Pred>
requires __detail::__can_take_while_view<_Range, _Pred>
constexpr auto
- operator()(_Range&& __r, _Pred&& __p) const
- [[nodiscard]]
+ operator() [[nodiscard]] (_Range&& __r, _Pred&& __p) const
{
return take_while_view(std::forward<_Range>(__r), std::forward<_Pred>(__p));
}
@@ -2363,8 +2358,7 @@ namespace views::__adaptor
template<viewable_range _Range, typename _Tp>
requires __detail::__can_drop_view<_Range, _Tp>
constexpr auto
- operator()(_Range&& __r, _Tp&& __n) const
- [[nodiscard]]
+ operator() [[nodiscard]] (_Range&& __r, _Tp&& __n) const
{
return drop_view(std::forward<_Range>(__r), std::forward<_Tp>(__n));
}
@@ -2452,8 +2446,7 @@ namespace views::__adaptor
template<viewable_range _Range, typename _Pred>
requires __detail::__can_drop_while_view<_Range, _Pred>
constexpr auto
- operator()(_Range&& __r, _Pred&& __p) const
- [[nodiscard]]
+ operator() [[nodiscard]] (_Range&& __r, _Pred&& __p) const
{
return drop_while_view(std::forward<_Range>(__r),
std::forward<_Pred>(__p));
@@ -2815,8 +2808,7 @@ namespace views::__adaptor
template<viewable_range _Range>
requires __detail::__can_join_view<_Range>
constexpr auto
- operator()(_Range&& __r) const
- [[nodiscard]]
+ operator() [[nodiscard]] (_Range&& __r) const
{
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 3474. Nesting join_views is broken because of CTAD
@@ -3267,8 +3259,7 @@ namespace views::__adaptor
template<viewable_range _Range, typename _Pattern>
requires __detail::__can_lazy_split_view<_Range, _Pattern>
constexpr auto
- operator()(_Range&& __r, _Pattern&& __f) const
- [[nodiscard]]
+ operator() [[nodiscard]] (_Range&& __r, _Pattern&& __f) const
{
return lazy_split_view(std::forward<_Range>(__r), std::forward<_Pattern>(__f));
}
@@ -3476,8 +3467,7 @@ namespace views::__adaptor
template<viewable_range _Range, typename _Pattern>
requires __detail::__can_split_view<_Range, _Pattern>
constexpr auto
- operator()(_Range&& __r, _Pattern&& __f) const
- [[nodiscard]]
+ operator() [[nodiscard]] (_Range&& __r, _Pattern&& __f) const
{
return split_view(std::forward<_Range>(__r), std::forward<_Pattern>(__f));
}
@@ -3498,8 +3488,7 @@ namespace views::__adaptor
{
template<input_or_output_iterator _Iter>
constexpr auto
- operator()(_Iter __i, iter_difference_t<_Iter> __n) const
- [[nodiscard]]
+ operator() [[nodiscard]] (_Iter __i, iter_difference_t<_Iter> __n) const
{
if constexpr (random_access_iterator<_Iter>)
return subrange(__i, __i + __n);
@@ -3620,8 +3609,7 @@ namespace views::__adaptor
requires __detail::__already_common<_Range>
|| __detail::__can_common_view<_Range>
constexpr auto
- operator()(_Range&& __r) const
- [[nodiscard]]
+ operator() [[nodiscard]] (_Range&& __r) const
{
if constexpr (__detail::__already_common<_Range>)
return views::all(std::forward<_Range>(__r));
@@ -3743,8 +3731,7 @@ namespace views::__adaptor
|| __detail::__is_reversible_subrange<remove_cvref_t<_Range>>
|| __detail::__can_reverse_view<_Range>
constexpr auto
- operator()(_Range&& __r) const
- [[nodiscard]]
+ operator() [[nodiscard]] (_Range&& __r) const
{
using _Tp = remove_cvref_t<_Range>;
if constexpr (__detail::__is_reverse_view<_Tp>)
@@ -4142,8 +4129,7 @@ namespace views::__adaptor
template<viewable_range _Range>
requires __detail::__can_elements_view<_Nm, _Range>
constexpr auto
- operator()(_Range&& __r) const
- [[nodiscard]]
+ operator() [[nodiscard]] (_Range&& __r) const
{
return elements_view<all_t<_Range>, _Nm>{std::forward<_Range>(__r)};
}
