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libstdc++: Add comparison operators to std::shared_ptr (PR 94562)

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This also implements the proposed resolution to LWG issue 3247, so that
the ill-formed <=> expression with nullptr is not used.

	PR libstdc++/94562
	* include/bits/shared_ptr.h (operator<=>): Define for C++20.
	* include/bits/shared_ptr_base.h (operator<=>): Likewise.
	* include/bits/unique_ptr.h (operator<=>): Add inline specifier.
	* testsuite/20_util/shared_ptr/comparison/cmp_c++20.cc: New test.
	* testsuite/20_util/shared_ptr/comparison/less.cc: Do not expect
	std::less<A*> to be used when comparing std::shared_ptr<A> objects in
	C++20.
This commit is contained in:
Jonathan Wakely 2020-04-14 21:54:55 +01:00
parent a126a1577f
commit f5fa62ed19
6 changed files with 158 additions and 2 deletions
libstdc++-v3
ChangeLog
include/bits
shared_ptr.hshared_ptr_base.hunique_ptr.h
testsuite/20_util/shared_ptr/comparison
cmp_c++20.ccless.cc

9
libstdc++-v3/ChangeLog

@ -1,5 +1,14 @@
2020-04-14 Jonathan Wakely <jwakely@redhat.com>
PR libstdc++/94562
* include/bits/shared_ptr.h (operator<=>): Define for C++20.
* include/bits/shared_ptr_base.h (operator<=>): Likewise.
* include/bits/unique_ptr.h (operator<=>): Add inline specifier.
* testsuite/20_util/shared_ptr/comparison/cmp_c++20.cc: New test.
* testsuite/20_util/shared_ptr/comparison/less.cc: Do not expect
std::less<A*> to be used when comparing std::shared_ptr<A> objects in
C++20.
PR libstdc++/94565
* libsupc++/compare (__unspec): Add noexcept-specifier to constructor.
* testsuite/18_support/comparisons/categories/94565.cc: New test.

16
libstdc++-v3/include/bits/shared_ptr.h

@ -442,6 +442,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
{ return !__a; }
#ifdef __cpp_lib_three_way_comparison
template<typename _Tp, typename _Up>
inline strong_ordering
operator<=>(const shared_ptr<_Tp>& __a,
const shared_ptr<_Up>& __b) noexcept
{ return compare_three_way()(__a.get(), __b.get()); }
template<typename _Tp>
inline strong_ordering
operator<=>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
{
using pointer = typename shared_ptr<_Tp>::element_type*;
return compare_three_way()(__a.get(), static_cast<pointer>(nullptr));
}
#else
/// shared_ptr comparison with nullptr
template<typename _Tp>
_GLIBCXX_NODISCARD inline bool
@ -548,6 +563,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_GLIBCXX_NODISCARD inline bool
operator>=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
{ return !(nullptr < __a); }
#endif
// 20.7.2.2.8 shared_ptr specialized algorithms.

19
libstdc++-v3/include/bits/shared_ptr_base.h

@ -54,6 +54,9 @@
#include <bits/refwrap.h>
#include <bits/stl_function.h>
#include <ext/aligned_buffer.h>
#if __cplusplus > 201703L
# include <compare>
#endif
namespace std _GLIBCXX_VISIBILITY(default)
{
@ -1442,6 +1445,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
operator==(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
{ return !__a; }
#ifdef __cpp_lib_three_way_comparison
template<typename _Tp, typename _Up, _Lock_policy _Lp>
inline strong_ordering
operator<=>(const __shared_ptr<_Tp, _Lp>& __a,
const __shared_ptr<_Up, _Lp>& __b) noexcept
{ return compare_three_way()(__a.get(), __b.get()); }
template<typename _Tp, _Lock_policy _Lp>
inline strong_ordering
operator<=>(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
{
using pointer = typename __shared_ptr<_Tp, _Lp>::element_type*;
return compare_three_way()(__a.get(), static_cast<pointer>(nullptr));
}
#else
template<typename _Tp, _Lock_policy _Lp>
inline bool
operator==(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
@ -1537,6 +1555,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
inline bool
operator>=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
{ return !(nullptr < __a); }
#endif // three-way comparison
// 20.7.2.2.8 shared_ptr specialized algorithms.
template<typename _Tp, _Lock_policy _Lp>

4
libstdc++-v3/include/bits/unique_ptr.h

@ -888,6 +888,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp, typename _Dp, typename _Up, typename _Ep>
requires three_way_comparable_with<typename unique_ptr<_Tp, _Dp>::pointer,
typename unique_ptr<_Up, _Ep>::pointer>
inline
compare_three_way_result_t<typename unique_ptr<_Tp, _Dp>::pointer,
typename unique_ptr<_Up, _Ep>::pointer>
operator<=>(const unique_ptr<_Tp, _Dp>& __x,
@ -896,11 +897,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp, typename _Dp>
requires three_way_comparable<typename unique_ptr<_Tp, _Dp>::pointer>
inline
compare_three_way_result_t<typename unique_ptr<_Tp, _Dp>::pointer>
operator<=>(const unique_ptr<_Tp, _Dp>& __x, nullptr_t)
{
using pointer = typename unique_ptr<_Tp, _Dp>::pointer;
return compare_three_way()(__x.get(), pointer(nullptr));
return compare_three_way()(__x.get(), static_cast<pointer>(nullptr));
}
#endif
// @} relates unique_ptr

106
libstdc++-v3/testsuite/20_util/shared_ptr/comparison/cmp_c++20.cc Normal file

@ -0,0 +1,106 @@
// Copyright (C) 2020 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
// { dg-options "-std=gnu++2a" }
// { dg-do run { target c++2a } }
#include <memory>
#include <testsuite_hooks.h>
void
test01()
{
std::shared_ptr<int> p0, p00;
VERIFY( p0 == p00 );
VERIFY( !(p0 < p00) );
VERIFY( !(p0 > p00) );
VERIFY( p0 <= p00 );
VERIFY( p0 >= p00 );
VERIFY( std::is_eq(p0 <=> p00) );
std::shared_ptr<int> p1(new int(1));
VERIFY( p1 == p1 );
VERIFY( !(p1 < p1) );
VERIFY( !(p1 > p1) );
VERIFY( p1 <= p1 );
VERIFY( p1 >= p1 );
VERIFY( std::is_eq(p1 <=> p1) );
std::shared_ptr<int> p11 = p1;
VERIFY( p11 == p1 );
VERIFY( !(p11 < p1) );
VERIFY( !(p11 > p1) );
VERIFY( p11 <= p1 );
VERIFY( p11 >= p1 );
VERIFY( std::is_eq(p11 <=> p1) );
std::shared_ptr<const int> p2(new int(1));
VERIFY( p1 >= p1 );
VERIFY( p1 != p2 );
VERIFY( (p1 < p2) || (p1 > p2) );
VERIFY( (p1 <= p2) || (p1 >= p2) );
VERIFY( std::is_neq(p1 <=> p2) );
VERIFY( p1 != p0 );
VERIFY( !(p1 < p0) );
VERIFY( p1 > p0 );
VERIFY( !(p1 <= p0) );
VERIFY( p1 >= p0 );
VERIFY( std::is_gt(p1 <=> p0) );
VERIFY( std::is_lt(p0 <=> p1) );
}
void
test02()
{
std::shared_ptr<int> p0;
VERIFY( p0 == nullptr );
VERIFY( !(p0 < nullptr) );
VERIFY( !(p0 > nullptr) );
VERIFY( p0 <= nullptr );
VERIFY( p0 >= nullptr );
VERIFY( std::is_eq(p0 <=> nullptr) );
VERIFY( nullptr == p0 );
VERIFY( !(nullptr < p0) );
VERIFY( !(nullptr > p0) );
VERIFY( nullptr <= p0 );
VERIFY( nullptr >= p0 );
VERIFY( std::is_eq(nullptr <=> p0) );
std::shared_ptr<int> p1(new int(1));
VERIFY( p1 != nullptr );
VERIFY( !(p1 < nullptr) );
VERIFY( p1 > nullptr );
VERIFY( !(p1 <= nullptr) );
VERIFY( p1 >= nullptr );
VERIFY( std::is_gt(p1 <=> nullptr) );
VERIFY( nullptr != p1 );
VERIFY( nullptr < p1 );
VERIFY( !(nullptr > p1) );
VERIFY( nullptr <= p1 );
VERIFY( !(nullptr >= p1) );
VERIFY( std::is_lt(nullptr <=> p1) );
}
int
main()
{
test01();
test02();
}

6
libstdc++-v3/testsuite/20_util/shared_ptr/comparison/less.cc

@ -46,7 +46,11 @@ test01()
std::shared_ptr<A> p1;
std::shared_ptr<A> p2;
VERIFY( !less(p1, p2) && !less(p2, p1) );
#ifndef __cpp_lib_three_way_comparison
// In C++20 std::less<std::shared_ptr<A>> uses the operator< synthesized
// from operator<=>, which uses std::compare_three_way not std::less<A*>.
VERIFY( std::less<A*>::count == 2 );
#endif
return 0;
}
@ -86,7 +90,7 @@ test03()
return 0;
}
int
int
main()
{
test01();