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libstdc++: Implement LWG 3324 for [cmp.alg] function objects (LWG 3324) 

LWG 3324 changed the [cmp.alg] types to use std::compare_three_way
instead of the <=> operator, but we were still using the old
specification. In order to make the existing tests pass the N::X type
needs to be equality comparable, so that three_way_comparable is
satisfied and compare_three_way can be used.

As part of this change I noticed that the compare_three_way call
operator was unconditionally noexcept, which is incorrect.

	* libsupc++/compare (compare_three_way): Fix noexcept-specifier.
	(strong_order, weak_order, partial_order): Replace uses of <=> with
	compare_three_way function object (LWG 3324).
	* testsuite/18_support/comparisons/algorithms/partial_order.cc: Add
	equality operator so that X satisfies three_way_comparable.
	* testsuite/18_support/comparisons/algorithms/strong_order.cc:
	Likewise.
	* testsuite/18_support/comparisons/algorithms/weak_order.cc: Likewise.
This commit is contained in:
Jonathan Wakely 2020-04-09 22:24:57 +01:00
parent 5b074864f8
commit 3fd1c229ad
5 changed files with 50 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
libstdc++-v3/ChangeLog
View File

@ -1,5 +1,14 @@
2020-04-09 Jonathan Wakely <jwakely@redhat.com>
* libsupc++/compare (compare_three_way): Fix noexcept-specifier.
(strong_order, weak_order, partial_order): Replace uses of <=> with
compare_three_way function object (LWG 3324).
* testsuite/18_support/comparisons/algorithms/partial_order.cc: Add
equality operator so that X satisfies three_way_comparable.
* testsuite/18_support/comparisons/algorithms/strong_order.cc:
Likewise.
* testsuite/18_support/comparisons/algorithms/weak_order.cc: Likewise.
* include/bits/unique_ptr.h (operator<=>): Define for C++20.
* testsuite/20_util/default_delete/48631_neg.cc: Adjust dg-error line.
* testsuite/20_util/default_delete/void_neg.cc: Likewise.

49
libstdc++-v3/libsupc++/compare
View File

@ -419,7 +419,8 @@ namespace std
= __detail::__weakly_eq_cmp_with<_Tp, _Tp>
&& __detail::__partially_ordered_with<_Tp, _Tp>
&& requires(const remove_reference_t<_Tp>& __a,
const remove_reference_t<_Tp>& __b) {
const remove_reference_t<_Tp>& __b)
{
{ __a <=> __b } -> __detail::__compares_as<_Cat>;
};
@ -435,7 +436,8 @@ namespace std
&& __detail::__weakly_eq_cmp_with<_Tp, _Up>
&& __detail::__partially_ordered_with<_Tp, _Up>
&& requires(const remove_reference_t<_Tp>& __t,
const remove_reference_t<_Up>& __u) {
const remove_reference_t<_Up>& __u)
{
{ __t <=> __u } -> __detail::__compares_as<_Cat>;
{ __u <=> __t } -> __detail::__compares_as<_Cat>;
};
@ -494,7 +496,8 @@ namespace std
template<typename _Tp, typename _Up>
requires three_way_comparable_with<_Tp, _Up>
constexpr auto
operator()(_Tp&& __t, _Up&& __u) const noexcept
operator()(_Tp&& __t, _Up&& __u) const
noexcept(noexcept(std::declval<_Tp>() <=> std::declval<_Up>()))
{
if constexpr (__detail::__3way_builtin_ptr_cmp<_Tp, _Up>)
{
@ -579,16 +582,16 @@ namespace std
};
template<typename _Ord, typename _Tp, typename _Up>
concept __op_cmp = requires(_Tp&& __t, _Up&& __u)
concept __cmp3way = requires(_Tp&& __t, _Up&& __u, compare_three_way __c)
{
_Ord(static_cast<_Tp&&>(__t) <=> static_cast<_Up&&>(__u));
_Ord(__c(static_cast<_Tp&&>(__t), static_cast<_Up&&>(__u)));
};
template<typename _Tp, typename _Up>
concept __strongly_ordered
= __adl_strong<_Tp, _Up>
// FIXME: || floating_point<remove_reference_t<_Tp>>
|| __op_cmp<strong_ordering, _Tp, _Up>;
|| __cmp3way<strong_ordering, _Tp, _Up>;
class _Strong_order
{
@ -601,8 +604,9 @@ namespace std
else if constexpr (__adl_strong<_Tp, _Up>)
return noexcept(strong_ordering(strong_order(std::declval<_Tp>(),
std::declval<_Up>())));
else if constexpr (__op_cmp<strong_ordering, _Tp, _Up>)
return noexcept(std::declval<_Tp>() <=> std::declval<_Up>());
else if constexpr (__cmp3way<strong_ordering, _Tp, _Up>)
return noexcept(compare_three_way()(std::declval<_Tp>(),
std::declval<_Up>()));
}
friend class _Weak_order;
@ -623,8 +627,9 @@ namespace std
else */ if constexpr (__adl_strong<_Tp, _Up>)
return strong_ordering(strong_order(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f)));
else if constexpr (__op_cmp<strong_ordering, _Tp, _Up>)
return static_cast<_Tp&&>(__e) <=> static_cast<_Up&&>(__f);
else if constexpr (__cmp3way<strong_ordering, _Tp, _Up>)
return compare_three_way()(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f));
}
};
@ -632,7 +637,7 @@ namespace std
concept __weakly_ordered
= floating_point<remove_reference_t<_Tp>>
|| __adl_weak<_Tp, _Up>
|| __op_cmp<weak_ordering, _Tp, _Up>
|| __cmp3way<weak_ordering, _Tp, _Up>
|| __strongly_ordered<_Tp, _Up>;
class _Weak_order
@ -646,8 +651,9 @@ namespace std
else if constexpr (__adl_weak<_Tp, _Up>)
return noexcept(weak_ordering(weak_order(std::declval<_Tp>(),
std::declval<_Up>())));
else if constexpr (__op_cmp<weak_ordering, _Tp, _Up>)
return noexcept(std::declval<_Tp>() <=> std::declval<_Up>());
else if constexpr (__cmp3way<weak_ordering, _Tp, _Up>)
return noexcept(compare_three_way()(std::declval<_Tp>(),
std::declval<_Up>()));
else if constexpr (__strongly_ordered<_Tp, _Up>)
return _Strong_order::_S_noexcept<_Tp, _Up>();
}
@ -669,8 +675,9 @@ namespace std
else if constexpr (__adl_weak<_Tp, _Up>)
return weak_ordering(weak_order(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f)));
else if constexpr (__op_cmp<weak_ordering, _Tp, _Up>)
return static_cast<_Tp&&>(__e) <=> static_cast<_Up&&>(__f);
else if constexpr (__cmp3way<weak_ordering, _Tp, _Up>)
return compare_three_way()(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f));
else if constexpr (__strongly_ordered<_Tp, _Up>)
return _Strong_order{}(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f));
@ -680,7 +687,7 @@ namespace std
template<typename _Tp, typename _Up>
concept __partially_ordered
= __adl_partial<_Tp, _Up>
|| __op_cmp<partial_ordering, _Tp, _Up>
|| __cmp3way<partial_ordering, _Tp, _Up>
|| __weakly_ordered<_Tp, _Up>;
class _Partial_order
@ -692,8 +699,9 @@ namespace std
if constexpr (__adl_partial<_Tp, _Up>)
return noexcept(partial_ordering(partial_order(std::declval<_Tp>(),
std::declval<_Up>())));
else if constexpr (__op_cmp<partial_ordering, _Tp, _Up>)
return noexcept(std::declval<_Tp>() <=> std::declval<_Up>());
else if constexpr (__cmp3way<partial_ordering, _Tp, _Up>)
return noexcept(compare_three_way()(std::declval<_Tp>(),
std::declval<_Up>()));
else if constexpr (__weakly_ordered<_Tp, _Up>)
return _Weak_order::_S_noexcept<_Tp, _Up>();
}
@ -712,8 +720,9 @@ namespace std
if constexpr (__adl_partial<_Tp, _Up>)
return partial_ordering(partial_order(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f)));
else if constexpr (__op_cmp<partial_ordering, _Tp, _Up>)
return static_cast<_Tp&&>(__e) <=> static_cast<_Up&&>(__f);
else if constexpr (__cmp3way<partial_ordering, _Tp, _Up>)
return compare_three_way()(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f));
else if constexpr (__weakly_ordered<_Tp, _Up>)
return _Weak_order{}(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f));

4
libstdc++-v3/testsuite/18_support/comparisons/algorithms/partial_order.cc
View File

@ -94,6 +94,10 @@ namespace N
return partial_ordering::equivalent;
return r.i <=> l.i;
}
constexpr bool operator==(X l, X r) { return std::is_eq(l <=> r); }
static_assert(std::three_way_comparable<X>);
}
void

4
libstdc++-v3/testsuite/18_support/comparisons/algorithms/strong_order.cc
View File

@ -47,6 +47,10 @@ namespace N
return strong_ordering::equivalent;
return r.i <=> l.i;
}
constexpr bool operator==(X l, X r) { return std::is_eq(l <=> r); }
static_assert(std::three_way_comparable<X>);
}
using N::X;

4
libstdc++-v3/testsuite/18_support/comparisons/algorithms/weak_order.cc
View File

@ -95,6 +95,10 @@ namespace N
return weak_ordering::equivalent;
return r.i <=> l.i;
}
constexpr bool operator==(X l, X r) { return std::is_eq(l <=> r); }
static_assert(std::three_way_comparable<X>);
}
void