In previous standards it is undefined for a container and its allocator
to have a different value_type. Libstdc++ has traditionally allowed it
as an extension, automatically rebinding the allocator to the
container's value_type. Since GCC 8.1 that extension has been disabled
for C++11 and later when __STRICT_ANSI__ is defined (i.e. for
-std=c++11, -std=c++14, -std=c++17 and -std=c++2a).
Since the acceptance of P1463R1 into the C++2a draft an incorrect
allocator::value_type now requires a diagnostic. This patch implements
that by enabling the static_assert for -std=gnu++2a as well.
* doc/xml/manual/status_cxx2020.xml: Document P1463R1 status.
* include/bits/forward_list.h [__cplusplus > 201703]: Enable
allocator::value_type assertion for C++2a.
* include/bits/hashtable.h: Likewise.
* include/bits/stl_deque.h: Likewise.
* include/bits/stl_list.h: Likewise.
* include/bits/stl_map.h: Likewise.
* include/bits/stl_multimap.h: Likewise.
* include/bits/stl_multiset.h: Likewise.
* include/bits/stl_set.h: Likewise.
* include/bits/stl_vector.h: Likewise.
* testsuite/23_containers/deque/48101-3_neg.cc: New test.
* testsuite/23_containers/forward_list/48101-3_neg.cc: New test.
* testsuite/23_containers/list/48101-3_neg.cc: New test.
* testsuite/23_containers/map/48101-3_neg.cc: New test.
* testsuite/23_containers/multimap/48101-3_neg.cc: New test.
* testsuite/23_containers/multiset/48101-3_neg.cc: New test.
* testsuite/23_containers/set/48101-3_neg.cc: New test.
* testsuite/23_containers/unordered_map/48101-3_neg.cc: New test.
* testsuite/23_containers/unordered_multimap/48101-3_neg.cc: New test.
* testsuite/23_containers/unordered_multiset/48101-3_neg.cc: New test.
* testsuite/23_containers/unordered_set/48101-3_neg.cc: New test.
* testsuite/23_containers/vector/48101-3_neg.cc: New test.
Tested x86_64-linux, committed to trunk.
commit e022e3a6d918af311e3770e9422badad1803d33f
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Mon Jun 3 13:53:49 2019 +0100
Enforce allocator::value_type consistency for containers in C++2a
In previous standards it is undefined for a container and its allocator
to have a different value_type. Libstdc++ has traditionally allowed it
as an extension, automatically rebinding the allocator to the
container's value_type. Since GCC 8.1 that extension has been disabled
for C++11 and later when __STRICT_ANSI__ is defined (i.e. for
-std=c++11, -std=c++14, -std=c++17 and -std=c++2a).
Since the acceptance of P1463R1 into the C++2a draft an incorrect
allocator::value_type now requires a diagnostic. This patch implements
that by enabling the static_assert for -std=gnu++2a as well.
* doc/xml/manual/status_cxx2020.xml: Document P1463R1 status.
* include/bits/forward_list.h [__cplusplus > 201703]: Enable
allocator::value_type assertion for C++2a.
* include/bits/hashtable.h: Likewise.
* include/bits/stl_deque.h: Likewise.
* include/bits/stl_list.h: Likewise.
* include/bits/stl_map.h: Likewise.
* include/bits/stl_multimap.h: Likewise.
* include/bits/stl_multiset.h: Likewise.
* include/bits/stl_set.h: Likewise.
* include/bits/stl_vector.h: Likewise.
* testsuite/23_containers/deque/48101-3_neg.cc: New test.
* testsuite/23_containers/forward_list/48101-3_neg.cc: New test.
* testsuite/23_containers/list/48101-3_neg.cc: New test.
* testsuite/23_containers/map/48101-3_neg.cc: New test.
* testsuite/23_containers/multimap/48101-3_neg.cc: New test.
* testsuite/23_containers/multiset/48101-3_neg.cc: New test.
* testsuite/23_containers/set/48101-3_neg.cc: New test.
* testsuite/23_containers/unordered_map/48101-3_neg.cc: New test.
* testsuite/23_containers/unordered_multimap/48101-3_neg.cc: New
test.
* testsuite/23_containers/unordered_multiset/48101-3_neg.cc: New
test.
* testsuite/23_containers/unordered_set/48101-3_neg.cc: New test.
* testsuite/23_containers/vector/48101-3_neg.cc: New test.
diff --git a/libstdc++-v3/doc/xml/manual/status_cxx2020.xml
b/libstdc++-v3/doc/xml/manual/status_cxx2020.xml
index 8a17747e3bd..4b0336931f4 100644
--- a/libstdc++-v3/doc/xml/manual/status_cxx2020.xml
+++ b/libstdc++-v3/doc/xml/manual/status_cxx2020.xml
@@ -951,6 +951,21 @@ Feature-testing recommendations for C++</link>.
<entry align="center"> 9.1 </entry>
<entry />
</row>
+
+ <row>
+ <entry>
+ Mandating the Standard Library:
+ Clause 21 - Containers library
+ </entry>
+ <entry>
+ <link xmlns:xlink="http://www.w3.org/1999/xlink";
xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1463r1.pdf";>
+ P1463R1
+ </link>
+ </entry>
+ <entry align="center"> 10 </entry>
+ <entry/>
+ </row>
+
</tbody>
</tgroup>
</table>
diff --git a/libstdc++-v3/include/bits/forward_list.h
b/libstdc++-v3/include/bits/forward_list.h
index 4c277845a51..e686283a432 100644
--- a/libstdc++-v3/include/bits/forward_list.h
+++ b/libstdc++-v3/include/bits/forward_list.h
@@ -421,7 +421,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
{
static_assert(is_same<typename remove_cv<_Tp>::type, _Tp>::value,
"std::forward_list must have a non-const, non-volatile value_type");
-#ifdef __STRICT_ANSI__
+#if __cplusplus > 201703L || defined __STRICT_ANSI__
static_assert(is_same<typename _Alloc::value_type, _Tp>::value,
"std::forward_list must have the same value_type as its allocator");
#endif
diff --git a/libstdc++-v3/include/bits/hashtable.h
b/libstdc++-v3/include/bits/hashtable.h
index ab24b5bb537..384e39877f2 100644
--- a/libstdc++-v3/include/bits/hashtable.h
+++ b/libstdc++-v3/include/bits/hashtable.h
@@ -188,7 +188,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
static_assert(is_same<typename remove_cv<_Value>::type, _Value>::value,
"unordered container must have a non-const, non-volatile value_type");
-#ifdef __STRICT_ANSI__
+#if __cplusplus > 201703L || defined __STRICT_ANSI__
static_assert(is_same<typename _Alloc::value_type, _Value>{},
"unordered container must have the same value_type as its allocator");
#endif
diff --git a/libstdc++-v3/include/bits/stl_deque.h
b/libstdc++-v3/include/bits/stl_deque.h
index 7dcb53823c4..ac76d681ff0 100644
--- a/libstdc++-v3/include/bits/stl_deque.h
+++ b/libstdc++-v3/include/bits/stl_deque.h
@@ -824,7 +824,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
#if __cplusplus >= 201103L
static_assert(is_same<typename remove_cv<_Tp>::type, _Tp>::value,
"std::deque must have a non-const, non-volatile value_type");
-# ifdef __STRICT_ANSI__
+# if __cplusplus > 201703L || defined __STRICT_ANSI__
static_assert(is_same<typename _Alloc::value_type, _Tp>::value,
"std::deque must have the same value_type as its allocator");
# endif
diff --git a/libstdc++-v3/include/bits/stl_list.h
b/libstdc++-v3/include/bits/stl_list.h
index 68bab94af1e..701982538df 100644
--- a/libstdc++-v3/include/bits/stl_list.h
+++ b/libstdc++-v3/include/bits/stl_list.h
@@ -563,7 +563,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
#if __cplusplus >= 201103L
static_assert(is_same<typename remove_cv<_Tp>::type, _Tp>::value,
"std::list must have a non-const, non-volatile value_type");
-# ifdef __STRICT_ANSI__
+# if __cplusplus > 201703L || defined __STRICT_ANSI__
static_assert(is_same<typename _Alloc::value_type, _Tp>::value,
"std::list must have the same value_type as its allocator");
# endif
diff --git a/libstdc++-v3/include/bits/stl_map.h
b/libstdc++-v3/include/bits/stl_map.h
index 322d0a8290a..b1083d572d6 100644
--- a/libstdc++-v3/include/bits/stl_map.h
+++ b/libstdc++-v3/include/bits/stl_map.h
@@ -118,7 +118,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
__glibcxx_class_requires2(value_type, _Alloc_value_type,
_SameTypeConcept)
#endif
-#if __cplusplus >= 201103L && defined(__STRICT_ANSI__)
+#if __cplusplus > 201703L || defined __STRICT_ANSI__
static_assert(is_same<typename _Alloc::value_type, value_type>::value,
"std::map must have the same value_type as its allocator");
#endif
diff --git a/libstdc++-v3/include/bits/stl_multimap.h
b/libstdc++-v3/include/bits/stl_multimap.h
index 4c4ccad3ac0..bb4aece96bf 100644
--- a/libstdc++-v3/include/bits/stl_multimap.h
+++ b/libstdc++-v3/include/bits/stl_multimap.h
@@ -117,7 +117,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
__glibcxx_class_requires2(value_type, _Alloc_value_type,
_SameTypeConcept)
#endif
-#if __cplusplus >= 201103L && defined(__STRICT_ANSI__)
+#if __cplusplus > 201703L || defined __STRICT_ANSI__
static_assert(is_same<typename _Alloc::value_type, value_type>::value,
"std::multimap must have the same value_type as its allocator");
#endif
diff --git a/libstdc++-v3/include/bits/stl_multiset.h
b/libstdc++-v3/include/bits/stl_multiset.h
index af733ea34dc..96fa14e2afa 100644
--- a/libstdc++-v3/include/bits/stl_multiset.h
+++ b/libstdc++-v3/include/bits/stl_multiset.h
@@ -109,7 +109,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
#if __cplusplus >= 201103L
static_assert(is_same<typename remove_cv<_Key>::type, _Key>::value,
"std::multiset must have a non-const, non-volatile value_type");
-# ifdef __STRICT_ANSI__
+# if __cplusplus > 201703L || defined __STRICT_ANSI__
static_assert(is_same<typename _Alloc::value_type, _Key>::value,
"std::multiset must have the same value_type as its allocator");
# endif
diff --git a/libstdc++-v3/include/bits/stl_set.h
b/libstdc++-v3/include/bits/stl_set.h
index 3131a7974b0..279b9705d78 100644
--- a/libstdc++-v3/include/bits/stl_set.h
+++ b/libstdc++-v3/include/bits/stl_set.h
@@ -107,7 +107,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
#if __cplusplus >= 201103L
static_assert(is_same<typename remove_cv<_Key>::type, _Key>::value,
"std::set must have a non-const, non-volatile value_type");
-# ifdef __STRICT_ANSI__
+# if __cplusplus > 201703L || defined __STRICT_ANSI__
static_assert(is_same<typename _Alloc::value_type, _Key>::value,
"std::set must have the same value_type as its allocator");
# endif
diff --git a/libstdc++-v3/include/bits/stl_vector.h
b/libstdc++-v3/include/bits/stl_vector.h
index dd9382d254d..d33e589498a 100644
--- a/libstdc++-v3/include/bits/stl_vector.h
+++ b/libstdc++-v3/include/bits/stl_vector.h
@@ -397,7 +397,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
#if __cplusplus >= 201103L
static_assert(is_same<typename remove_cv<_Tp>::type, _Tp>::value,
"std::vector must have a non-const, non-volatile value_type");
-# ifdef __STRICT_ANSI__
+# if __cplusplus > 201703L || defined __STRICT_ANSI__
static_assert(is_same<typename _Alloc::value_type, _Tp>::value,
"std::vector must have the same value_type as its allocator");
# endif
diff --git a/libstdc++-v3/testsuite/23_containers/deque/48101-3_neg.cc
b/libstdc++-v3/testsuite/23_containers/deque/48101-3_neg.cc
new file mode 100644
index 00000000000..724b3de6a03
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/deque/48101-3_neg.cc
@@ -0,0 +1,29 @@
+// Copyright (C) 2017-2019 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 compile { target c++2a } }
+
+#include <deque>
+
+void
+test01()
+{
+ std::deque<int, std::allocator<long>> c;
+}
+
+// { dg-error "same value_type as its allocator" "" { target *-*-* } 0 }
diff --git a/libstdc++-v3/testsuite/23_containers/forward_list/48101-3_neg.cc
b/libstdc++-v3/testsuite/23_containers/forward_list/48101-3_neg.cc
new file mode 100644
index 00000000000..d0e56f59494
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/forward_list/48101-3_neg.cc
@@ -0,0 +1,29 @@
+// Copyright (C) 2017-2019 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 compile { target c++2a } }
+
+#include <forward_list>
+
+void
+test01()
+{
+ std::forward_list<int, std::allocator<long>> c;
+}
+
+// { dg-error "same value_type as its allocator" "" { target *-*-* } 0 }
diff --git a/libstdc++-v3/testsuite/23_containers/list/48101-3_neg.cc
b/libstdc++-v3/testsuite/23_containers/list/48101-3_neg.cc
new file mode 100644
index 00000000000..ce32e9ced82
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/list/48101-3_neg.cc
@@ -0,0 +1,29 @@
+// Copyright (C) 2017-2019 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 compile { target c++2a } }
+
+#include <list>
+
+void
+test01()
+{
+ std::list<int, std::allocator<long>> c;
+}
+
+// { dg-error "same value_type as its allocator" "" { target *-*-* } 0 }
diff --git a/libstdc++-v3/testsuite/23_containers/map/48101-3_neg.cc
b/libstdc++-v3/testsuite/23_containers/map/48101-3_neg.cc
new file mode 100644
index 00000000000..dfce9c2179c
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/map/48101-3_neg.cc
@@ -0,0 +1,29 @@
+// Copyright (C) 2017-2019 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 compile { target c++2a } }
+
+#include <map>
+
+void
+test01()
+{
+ std::map<int, int, std::less<int>, std::allocator<int>> c;
+}
+
+// { dg-error "same value_type as its allocator" "" { target *-*-* } 0 }
diff --git a/libstdc++-v3/testsuite/23_containers/multimap/48101-3_neg.cc
b/libstdc++-v3/testsuite/23_containers/multimap/48101-3_neg.cc
new file mode 100644
index 00000000000..77769498548
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/multimap/48101-3_neg.cc
@@ -0,0 +1,29 @@
+// Copyright (C) 2017-2019 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 compile { target c++2a } }
+
+#include <map>
+
+void
+test01()
+{
+ std::multimap<int, int, std::less<int>, std::allocator<int>> c;
+}
+
+// { dg-error "same value_type as its allocator" "" { target *-*-* } 0 }
diff --git a/libstdc++-v3/testsuite/23_containers/multiset/48101-3_neg.cc
b/libstdc++-v3/testsuite/23_containers/multiset/48101-3_neg.cc
new file mode 100644
index 00000000000..209a1d5deeb
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/multiset/48101-3_neg.cc
@@ -0,0 +1,29 @@
+// Copyright (C) 2017-2019 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 compile { target c++2a } }
+
+#include <set>
+
+void
+test01()
+{
+ std::multiset<int, std::less<int>, std::allocator<long>> c;
+}
+
+// { dg-error "same value_type as its allocator" "" { target *-*-* } 0 }
diff --git a/libstdc++-v3/testsuite/23_containers/set/48101-3_neg.cc
b/libstdc++-v3/testsuite/23_containers/set/48101-3_neg.cc
new file mode 100644
index 00000000000..75777370a3a
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/set/48101-3_neg.cc
@@ -0,0 +1,29 @@
+// Copyright (C) 2017-2019 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 compile { target c++2a } }
+
+#include <set>
+
+void
+test01()
+{
+ std::set<int, std::less<int>, std::allocator<long>> c;
+}
+
+// { dg-error "same value_type as its allocator" "" { target *-*-* } 0 }
diff --git a/libstdc++-v3/testsuite/23_containers/unordered_map/48101-3_neg.cc
b/libstdc++-v3/testsuite/23_containers/unordered_map/48101-3_neg.cc
new file mode 100644
index 00000000000..98bcd8c755b
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/unordered_map/48101-3_neg.cc
@@ -0,0 +1,30 @@
+// Copyright (C) 2017-2019 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 compile { target c++2a } }
+
+#include <unordered_map>
+
+void
+test01()
+{
+ using namespace std;
+ unordered_map<int, int, hash<int>, equal_to<int>, allocator<long>> c;
+}
+
+// { dg-error "same value_type as its allocator" "" { target *-*-* } 0 }
diff --git
a/libstdc++-v3/testsuite/23_containers/unordered_multimap/48101-3_neg.cc
b/libstdc++-v3/testsuite/23_containers/unordered_multimap/48101-3_neg.cc
new file mode 100644
index 00000000000..3bda27b8354
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/unordered_multimap/48101-3_neg.cc
@@ -0,0 +1,30 @@
+// Copyright (C) 2017-2019 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 compile { target c++2a } }
+
+#include <unordered_map>
+
+void
+test01()
+{
+ using namespace std;
+ unordered_multimap<int, int, hash<int>, equal_to<int>, allocator<long>> c;
+}
+
+// { dg-error "same value_type as its allocator" "" { target *-*-* } 0 }
diff --git
a/libstdc++-v3/testsuite/23_containers/unordered_multiset/48101-3_neg.cc
b/libstdc++-v3/testsuite/23_containers/unordered_multiset/48101-3_neg.cc
new file mode 100644
index 00000000000..620c9b703bd
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/unordered_multiset/48101-3_neg.cc
@@ -0,0 +1,30 @@
+// Copyright (C) 2017-2019 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 compile { target c++2a } }
+
+#include <unordered_set>
+
+void
+test01()
+{
+ using namespace std;
+ unordered_multiset<int, hash<int>, equal_to<int>, allocator<long>> c;
+}
+
+// { dg-error "same value_type as its allocator" "" { target *-*-* } 0 }
diff --git a/libstdc++-v3/testsuite/23_containers/unordered_set/48101-3_neg.cc
b/libstdc++-v3/testsuite/23_containers/unordered_set/48101-3_neg.cc
new file mode 100644
index 00000000000..c226c5236f8
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/unordered_set/48101-3_neg.cc
@@ -0,0 +1,30 @@
+// Copyright (C) 2017-2019 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 compile { target c++2a } }
+
+#include <unordered_set>
+
+void
+test01()
+{
+ using namespace std;
+ unordered_set<int, hash<int>, equal_to<int>, allocator<long>> c;
+}
+
+// { dg-error "same value_type as its allocator" "" { target *-*-* } 0 }
diff --git a/libstdc++-v3/testsuite/23_containers/vector/48101-3_neg.cc
b/libstdc++-v3/testsuite/23_containers/vector/48101-3_neg.cc
new file mode 100644
index 00000000000..2317efa1516
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/vector/48101-3_neg.cc
@@ -0,0 +1,29 @@
+// Copyright (C) 2017-2019 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 compile { target c++2a } }
+
+#include <vector>
+
+void
+test01()
+{
+ std::vector<int, std::allocator<long>> c;
+}
+
+// { dg-error "same value_type as its allocator" "" { target *-*-* } 0 }
