diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index f7e0022e38f8145c2f236c324f8deb8f4c5f67cc..fde5ac1bf376e5515914b5c5bed4b69db17c01ed 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,5 +1,10 @@
2020-04-19 Jonathan Wakely <jwakely@redhat.com>
+ * include/bits/stl_queue.h (queue): Define operator<=> for C++20.
+ * include/bits/stl_stack.h (stack): Likewise.
+ * testsuite/23_containers/queue/cmp_c++20.cc: New test.
+ * testsuite/23_containers/stack/cmp_c++20.cc: New test.
+
* include/bits/unordered_map.h (unordered_map, unordered_multimap):
Remove redundant operator!= for C++20.
* include/bits/unordered_set.h (unordered_set, unordered_multiset):
diff --git a/libstdc++-v3/include/bits/stl_queue.h b/libstdc++-v3/include/bits/stl_queue.h
index d2b2705c7c3582a64e55834b8d6b5e8a8424e9ef..8635d4267900eb59614d4cd73d4c98f2df3bf834 100644
--- a/libstdc++-v3/include/bits/stl_queue.h
+++ b/libstdc++-v3/include/bits/stl_queue.h
@@ -114,6 +114,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
friend bool
operator<(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
+#if __cpp_lib_three_way_comparison
+ template<typename _Tp1, three_way_comparable _Seq1>
+ friend compare_three_way_result_t<_Seq1>
+ operator<=>(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
+#endif
+
#if __cplusplus >= 201103L
template<typename _Alloc>
using _Uses = typename
@@ -380,6 +386,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
operator>=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
{ return !(__x < __y); }
+#if __cpp_lib_three_way_comparison
+ template<typename _Tp, three_way_comparable _Seq>
+ inline compare_three_way_result_t<_Seq>
+ operator<=>(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
+ { return __x.c <=> __y.c; }
+#endif
+
#if __cplusplus >= 201103L
template<typename _Tp, typename _Seq>
inline
diff --git a/libstdc++-v3/include/bits/stl_stack.h b/libstdc++-v3/include/bits/stl_stack.h
index 355966a90e0809d39251b4eb1d5610de853f465f..1ce98a94ab98aff060ef3f25b6b0395346ee42f5 100644
--- a/libstdc++-v3/include/bits/stl_stack.h
+++ b/libstdc++-v3/include/bits/stl_stack.h
@@ -116,6 +116,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
friend bool
operator<(const stack<_Tp1, _Seq1>&, const stack<_Tp1, _Seq1>&);
+#if __cpp_lib_three_way_comparison
+ template<typename _Tp1, three_way_comparable _Seq1>
+ friend compare_three_way_result_t<_Seq1>
+ operator<=>(const stack<_Tp1, _Seq1>&, const stack<_Tp1, _Seq1>&);
+#endif
+
#if __cplusplus >= 201103L
template<typename _Alloc>
using _Uses = typename
@@ -355,6 +361,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
operator>=(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)
{ return !(__x < __y); }
+#if __cpp_lib_three_way_comparison
+ template<typename _Tp, three_way_comparable _Seq>
+ inline compare_three_way_result_t<_Seq>
+ operator<=>(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)
+ { return __x.c <=> __y.c; }
+#endif
+
#if __cplusplus >= 201103L
template<typename _Tp, typename _Seq>
inline
diff --git a/libstdc++-v3/testsuite/23_containers/queue/cmp_c++20.cc b/libstdc++-v3/testsuite/23_containers/queue/cmp_c++20.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5d0d4c9749e3a713b6c17c8ccc8bba2adf36137c
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/queue/cmp_c++20.cc
@@ -0,0 +1,60 @@
+// 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 <queue>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+ std::queue<int> c1{ {1, 2, 3} }, c2{ {1, 2, 3, 4} }, c3{ {1, 2, 4} };
+ VERIFY( c1 == c1 );
+ VERIFY( std::is_eq(c1 <=> c1) );
+ VERIFY( c1 < c2 );
+ VERIFY( std::is_lt(c1 <=> c2) );
+ VERIFY( c1 < c3 );
+ VERIFY( std::is_lt(c1 <=> c3) );
+ VERIFY( c2 < c3 );
+ VERIFY( std::is_lt(c2 <=> c3) );
+
+ static_assert( std::totally_ordered<std::queue<int>> );
+
+ static_assert( std::three_way_comparable<std::queue<int>,
+ std::strong_ordering> );
+ static_assert( ! std::three_way_comparable<std::queue<float>,
+ std::strong_ordering> );
+ static_assert( ! std::three_way_comparable<std::queue<float>,
+ std::weak_ordering> );
+ static_assert( std::three_way_comparable<std::queue<float>,
+ std::partial_ordering> );
+
+ struct E
+ {
+ bool operator==(E) { return true; }
+ };
+ static_assert( ! std::three_way_comparable<E> );
+ static_assert( ! std::three_way_comparable<std::queue<E>> );
+}
+
+int
+main()
+{
+ test01();
+}
diff --git a/libstdc++-v3/testsuite/23_containers/stack/cmp_c++20.cc b/libstdc++-v3/testsuite/23_containers/stack/cmp_c++20.cc
new file mode 100644
index 0000000000000000000000000000000000000000..054e487751f278f22b73afad4a60e794ecf26745
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/stack/cmp_c++20.cc
@@ -0,0 +1,60 @@
+// 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 <stack>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+ std::stack<int> c1{ {1, 2, 3} }, c2{ {1, 2, 3, 4} }, c3{ {1, 2, 4} };
+ VERIFY( c1 == c1 );
+ VERIFY( std::is_eq(c1 <=> c1) );
+ VERIFY( c1 < c2 );
+ VERIFY( std::is_lt(c1 <=> c2) );
+ VERIFY( c1 < c3 );
+ VERIFY( std::is_lt(c1 <=> c3) );
+ VERIFY( c2 < c3 );
+ VERIFY( std::is_lt(c2 <=> c3) );
+
+ static_assert( std::totally_ordered<std::stack<int>> );
+
+ static_assert( std::three_way_comparable<std::stack<int>,
+ std::strong_ordering> );
+ static_assert( ! std::three_way_comparable<std::stack<float>,
+ std::strong_ordering> );
+ static_assert( ! std::three_way_comparable<std::stack<float>,
+ std::weak_ordering> );
+ static_assert( std::three_way_comparable<std::stack<float>,
+ std::partial_ordering> );
+
+ struct E
+ {
+ bool operator==(E) { return true; }
+ };
+ static_assert( ! std::three_way_comparable<E> );
+ static_assert( ! std::three_way_comparable<std::stack<E>> );
+}
+
+int
+main()
+{
+ test01();
+}