Implement P0084R2, Emplace return type, for C++17

	* doc/xml/manual/status_cxx2017.xml: Update status.
	* doc/html/*: Regenerate.
	* include/bits/deque.tcc (deque::emplace_front, deque::emplace_back):
	Return a reference in C++17 mode.
	* include/bits/forward_list.h (forward_list::emplace_front): Likewise.
	* include/bits/stl_bvector.h (vector<bool>::emplace_back): Likewise.
	* include/bits/stl_deque.h (deque::emplace_front, deque::emplace_back):
	Likewise.
	* include/bits/stl_list.h (list::emplace_front, list::emplace_back):
	Likewise.
	* include/bits/stl_queue.h (queue::emplace): Likewise.
	* include/bits/stl_stack.h (stack::emplace): Likewise.
	* include/bits/stl_vector.h (vector::emplace_back): Likewise.
	* include/bits/vector.tcc (vector::emplace_back): Likewise.
	* include/debug/deque (__gnu_debug::deque::emplace_front)
	(__gnu_debug::deque::emplace_back): Likewise.
	* include/debug/vector (__gnu_debug::vector::emplace_back): Likewise.
	* testsuite/23_containers/deque/modifiers/emplace/cxx17_return.cc:
	New.
	* testsuite/23_containers/forward_list/modifiers/
	emplace_cxx17_return.cc: New.
	* testsuite/23_containers/list/modifiers/emplace/cxx17_return.cc: New.
	* testsuite/23_containers/queue/members/emplace_cxx17_return.cc: New.
	* testsuite/23_containers/stack/members/emplace_cxx17_return.cc: New.
	* testsuite/23_containers/vector/bool/emplace_cxx17_return.cc: New.
	* testsuite/23_containers/vector/modifiers/emplace/cxx17_return.cc:
	New.

From-SVN: r241234

22 files changed, 440 insertions, 15 deletions

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 5f72a96..b31c1dd 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,33 @@
+2016-10-17  Jonathan Wakely  <jwakely@redhat.com>
+
+	* doc/xml/manual/status_cxx2017.xml: Update status.
+	* doc/html/*: Regenerate.
+	* include/bits/deque.tcc (deque::emplace_front, deque::emplace_back):
+	Return a reference in C++17 mode.
+	* include/bits/forward_list.h (forward_list::emplace_front): Likewise.
+	* include/bits/stl_bvector.h (vector<bool>::emplace_back): Likewise.
+	* include/bits/stl_deque.h (deque::emplace_front, deque::emplace_back):
+	Likewise.
+	* include/bits/stl_list.h (list::emplace_front, list::emplace_back):
+	Likewise.
+	* include/bits/stl_queue.h (queue::emplace): Likewise.
+	* include/bits/stl_stack.h (stack::emplace): Likewise.
+	* include/bits/stl_vector.h (vector::emplace_back): Likewise.
+	* include/bits/vector.tcc (vector::emplace_back): Likewise.
+	* include/debug/deque (__gnu_debug::deque::emplace_front)
+	(__gnu_debug::deque::emplace_back): Likewise.
+	* include/debug/vector (__gnu_debug::vector::emplace_back): Likewise.
+	* testsuite/23_containers/deque/modifiers/emplace/cxx17_return.cc:
+	New.
+	* testsuite/23_containers/forward_list/modifiers/
+	emplace_cxx17_return.cc: New.
+	* testsuite/23_containers/list/modifiers/emplace/cxx17_return.cc: New.
+	* testsuite/23_containers/queue/members/emplace_cxx17_return.cc: New.
+	* testsuite/23_containers/stack/members/emplace_cxx17_return.cc: New.
+	* testsuite/23_containers/vector/bool/emplace_cxx17_return.cc: New.
+	* testsuite/23_containers/vector/modifiers/emplace/cxx17_return.cc:
+	New.
+
 2016-10-16  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	* testsuite/22_locale/classification/isblank.cc: Remove 'test'
diff --git a/libstdc++-v3/doc/html/manual/status.html b/libstdc++-v3/doc/html/manual/status.html
index 5ef66da..7a79f0d 100644
--- a/libstdc++-v3/doc/html/manual/status.html
+++ b/libstdc++-v3/doc/html/manual/status.html
@@ -706,11 +706,11 @@ Feature-testing recommendations for C++</a>.
 	</a>
       </td><td align="center"> 6.2 (3.0)</td><td align="left"><code class="code"> __cpp_lib_incomplete_container_elements &gt;= 201505 </code>
 	     (the feature was always supported, but the macro was not defined until GCC 6.2)
-      </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Emplace return type </td><td align="left">
+      </td></tr><tr><td align="left"> Emplace return type </td><td align="left">
 	<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0084r2.pdf" target="_top">
 	P0084R2
 	</a>
-      </td><td align="center"> No </td><td align="left"> </td></tr><tr><td align="left">Improved insertion interface for unique-key maps</td><td align="left">
+      </td><td align="center"> 7 </td><td align="left"> </td></tr><tr><td align="left">Improved insertion interface for unique-key maps</td><td align="left">
 	<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4279.html" target="_top">
 	  N4279
 	</a>
diff --git a/libstdc++-v3/doc/html/manual/test.html b/libstdc++-v3/doc/html/manual/test.html
index 9e5b64f..f37d7be 100644
--- a/libstdc++-v3/doc/html/manual/test.html
+++ b/libstdc++-v3/doc/html/manual/test.html
@@ -322,7 +322,7 @@ cat 27_io/objects/char/3_xin.in | a.out</pre></dd><dt><span class="term"><code c
       <span class="command"><strong>make</strong></span>, or via options for the DejaGnu test framework
       (described below). The latter approach uses the
       <code class="option">--target_board</code> option that was shown earlier.
-      For example, to run the tests with <code class="option">-O1 -D_GLIBCXX_ASSERT</code>
+      For example, to run the tests with <code class="option">-O1 -D_GLIBCXX_ASSERTIONS</code>
       you could use:
 </p><pre class="programlisting">    make RUNTESTFLAGS=--target_board=unix/-O1/-D_GLIBCXX_ASSERTIONS</pre><p>
     </p><p>
diff --git a/libstdc++-v3/doc/xml/manual/status_cxx2017.xml b/libstdc++-v3/doc/xml/manual/status_cxx2017.xml
index ae8dfa9..a1190bc 100644
--- a/libstdc++-v3/doc/xml/manual/status_cxx2017.xml
+++ b/libstdc++-v3/doc/xml/manual/status_cxx2017.xml
@@ -542,14 +542,13 @@ Feature-testing recommendations for C++</link>.
     </row>
 
     <row>
-      <?dbhtml bgcolor="#C8B0B0" ?>
       <entry> Emplace return type </entry>
       <entry>
 	<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0084r2.pdf">
 	P0084R2
 	</link>
       </entry>
-      <entry align="center"> No </entry>
+      <entry align="center"> 7 </entry>
       <entry/>
     </row>
 
diff --git a/libstdc++-v3/include/bits/deque.tcc b/libstdc++-v3/include/bits/deque.tcc
index 96ec9f8..796b0cd 100644
--- a/libstdc++-v3/include/bits/deque.tcc
+++ b/libstdc++-v3/include/bits/deque.tcc
@@ -129,7 +129,11 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 #if __cplusplus >= 201103L
   template<typename _Tp, typename _Alloc>
     template<typename... _Args>
+#if __cplusplus > 201402L
+      typename deque<_Tp, _Alloc>::reference
+#else
       void
+#endif
       deque<_Tp, _Alloc>::
       emplace_front(_Args&&... __args)
       {
@@ -142,11 +146,18 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 	  }
 	else
 	  _M_push_front_aux(std::forward<_Args>(__args)...);
+#if __cplusplus > 201402L
+	return front();
+#endif
       }
 
   template<typename _Tp, typename _Alloc>
     template<typename... _Args>
+#if __cplusplus > 201402L
+      typename deque<_Tp, _Alloc>::reference
+#else
       void
+#endif
       deque<_Tp, _Alloc>::
       emplace_back(_Args&&... __args)
       {
@@ -160,6 +171,9 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 	  }
 	else
 	  _M_push_back_aux(std::forward<_Args>(__args)...);
+#if __cplusplus > 201402L
+	return back();
+#endif
       }
 #endif
 
diff --git a/libstdc++-v3/include/bits/forward_list.h b/libstdc++-v3/include/bits/forward_list.h
index 3961509..0ea8806 100644
--- a/libstdc++-v3/include/bits/forward_list.h
+++ b/libstdc++-v3/include/bits/forward_list.h
@@ -797,10 +797,19 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
        *  and references.
        */
       template<typename... _Args>
-        void
+#if __cplusplus > 201402L
+        reference
+#else
+	void
+#endif
         emplace_front(_Args&&... __args)
-        { this->_M_insert_after(cbefore_begin(),
-                                std::forward<_Args>(__args)...); }
+        {
+	  this->_M_insert_after(cbefore_begin(),
+                                std::forward<_Args>(__args)...);
+#if __cplusplus > 201402L
+	  return front();
+#endif
+	}
 
       /**
        *  @brief  Add data to the front of the %forward_list.
diff --git a/libstdc++-v3/include/bits/stl_bvector.h b/libstdc++-v3/include/bits/stl_bvector.h
index b3ac63f..2e231b9 100644
--- a/libstdc++-v3/include/bits/stl_bvector.h
+++ b/libstdc++-v3/include/bits/stl_bvector.h
@@ -1056,9 +1056,18 @@ template<typename _Alloc>
 
 #if __cplusplus >= 201103L
     template<typename... _Args>
+#if __cplusplus > 201402L
+      reference
+#else
       void
+#endif
       emplace_back(_Args&&... __args)
-      { push_back(bool(__args...)); }
+      {
+	push_back(bool(__args...));
+#if __cplusplus > 201402L
+	return back();
+#endif
+      }
 
     template<typename... _Args>
       iterator
diff --git a/libstdc++-v3/include/bits/stl_deque.h b/libstdc++-v3/include/bits/stl_deque.h
index 7192f65..8539a08 100644
--- a/libstdc++-v3/include/bits/stl_deque.h
+++ b/libstdc++-v3/include/bits/stl_deque.h
@@ -1519,7 +1519,11 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
       { emplace_front(std::move(__x)); }
 
       template<typename... _Args>
-        void
+#if __cplusplus > 201402L
+	reference
+#else
+	void
+#endif
         emplace_front(_Args&&... __args);
 #endif
 
@@ -1552,7 +1556,11 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
       { emplace_back(std::move(__x)); }
 
       template<typename... _Args>
-        void
+#if __cplusplus > 201402L
+	reference
+#else
+	void
+#endif
         emplace_back(_Args&&... __args);
 #endif
 
diff --git a/libstdc++-v3/include/bits/stl_list.h b/libstdc++-v3/include/bits/stl_list.h
index 87c8a39..8693a6f 100644
--- a/libstdc++-v3/include/bits/stl_list.h
+++ b/libstdc++-v3/include/bits/stl_list.h
@@ -1069,9 +1069,18 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
       { this->_M_insert(begin(), std::move(__x)); }
 
       template<typename... _Args>
-        void
+#if __cplusplus > 201402L
+        reference
+#else
+	void
+#endif
         emplace_front(_Args&&... __args)
-        { this->_M_insert(begin(), std::forward<_Args>(__args)...); }
+        {
+	  this->_M_insert(begin(), std::forward<_Args>(__args)...);
+#if __cplusplus > 201402L
+	  return front();
+#endif
+	}
 #endif
 
       /**
@@ -1110,9 +1119,18 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
       { this->_M_insert(end(), std::move(__x)); }
 
       template<typename... _Args>
-        void
+#if __cplusplus > 201402L
+        reference
+#else
+	void
+#endif
         emplace_back(_Args&&... __args)
-        { this->_M_insert(end(), std::forward<_Args>(__args)...); }
+        {
+	  this->_M_insert(end(), std::forward<_Args>(__args)...);
+#if __cplusplus > 201402L
+        return back();
+#endif
+	}
 #endif
 
       /**
diff --git a/libstdc++-v3/include/bits/stl_queue.h b/libstdc++-v3/include/bits/stl_queue.h
index 843199c..178e4b2 100644
--- a/libstdc++-v3/include/bits/stl_queue.h
+++ b/libstdc++-v3/include/bits/stl_queue.h
@@ -247,11 +247,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       push(value_type&& __x)
       { c.push_back(std::move(__x)); }
 
+#if __cplusplus > 201402L
+      template<typename... _Args>
+	decltype(auto)
+	emplace(_Args&&... __args)
+	{ return c.emplace_back(std::forward<_Args>(__args)...); }
+#else
       template<typename... _Args>
         void
         emplace(_Args&&... __args)
 	{ c.emplace_back(std::forward<_Args>(__args)...); }
 #endif
+#endif
 
       /**
        *  @brief  Removes first element.
diff --git a/libstdc++-v3/include/bits/stl_stack.h b/libstdc++-v3/include/bits/stl_stack.h
index 612913d..ebc8816 100644
--- a/libstdc++-v3/include/bits/stl_stack.h
+++ b/libstdc++-v3/include/bits/stl_stack.h
@@ -223,11 +223,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       push(value_type&& __x)
       { c.push_back(std::move(__x)); }
 
+#if __cplusplus > 201402L
+      template<typename... _Args>
+	decltype(auto)
+	emplace(_Args&&... __args)
+	{ return c.emplace_back(std::forward<_Args>(__args)...); }
+#else
       template<typename... _Args>
         void
         emplace(_Args&&... __args)
 	{ c.emplace_back(std::forward<_Args>(__args)...); }
 #endif
+#endif
 
       /**
        *  @brief  Removes first element.
diff --git a/libstdc++-v3/include/bits/stl_vector.h b/libstdc++-v3/include/bits/stl_vector.h
index 9a05dd5..efc569b 100644
--- a/libstdc++-v3/include/bits/stl_vector.h
+++ b/libstdc++-v3/include/bits/stl_vector.h
@@ -960,7 +960,11 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
       { emplace_back(std::move(__x)); }
 
       template<typename... _Args>
+#if __cplusplus > 201402L
+        reference
+#else
 	void
+#endif
 	emplace_back(_Args&&... __args);
 #endif
 
diff --git a/libstdc++-v3/include/bits/vector.tcc b/libstdc++-v3/include/bits/vector.tcc
index 6926a8b..b6050d3 100644
--- a/libstdc++-v3/include/bits/vector.tcc
+++ b/libstdc++-v3/include/bits/vector.tcc
@@ -87,7 +87,11 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 #if __cplusplus >= 201103L
   template<typename _Tp, typename _Alloc>
     template<typename... _Args>
+#if __cplusplus > 201402L
+      typename vector<_Tp, _Alloc>::reference
+#else
       void
+#endif
       vector<_Tp, _Alloc>::
       emplace_back(_Args&&... __args)
       {
@@ -99,6 +103,9 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 	  }
 	else
 	  _M_realloc_insert(end(), std::forward<_Args>(__args)...);
+#if __cplusplus > 201402L
+	return back();
+#endif
       }
 #endif
 
diff --git a/libstdc++-v3/include/debug/deque b/libstdc++-v3/include/debug/deque
index f15faad..bf4cba6 100644
--- a/libstdc++-v3/include/debug/deque
+++ b/libstdc++-v3/include/debug/deque
@@ -386,19 +386,33 @@ namespace __debug
       { emplace_back(std::move(__x)); }
 
       template<typename... _Args>
+#if __cplusplus > 201402L
+	reference
+#else
 	void
+#endif
 	emplace_front(_Args&&... __args)
 	{
 	  _Base::emplace_front(std::forward<_Args>(__args)...);
 	  this->_M_invalidate_all();
+#if __cplusplus > 201402L
+	  return front();
+#endif
 	}
 
       template<typename... _Args>
+#if __cplusplus > 201402L
+	reference
+#else
 	void
+#endif
 	emplace_back(_Args&&... __args)
 	{
 	  _Base::emplace_back(std::forward<_Args>(__args)...);
 	  this->_M_invalidate_all();
+#if __cplusplus > 201402L
+	  return back();
+#endif
 	}
 
       template<typename... _Args>
diff --git a/libstdc++-v3/include/debug/vector b/libstdc++-v3/include/debug/vector
index 9bcda73..b2d70bd 100644
--- a/libstdc++-v3/include/debug/vector
+++ b/libstdc++-v3/include/debug/vector
@@ -478,7 +478,11 @@ namespace __debug
 	{ emplace_back(std::move(__x)); }
 
       template<typename... _Args>
+#if __cplusplus > 201402L
+	deque<_Tp, _Alloc>::reference
+#else
 	void
+#endif
 	emplace_back(_Args&&... __args)
 	{
 	  bool __realloc = this->_M_requires_reallocation(this->size() + 1);
@@ -486,6 +490,9 @@ namespace __debug
 	  if (__realloc)
 	    this->_M_invalidate_all();
 	  this->_M_update_guaranteed_capacity();
+#if __cplusplus > 201402L
+	  return back();
+#endif
 	}
 #endif
 
diff --git a/libstdc++-v3/testsuite/23_containers/deque/modifiers/emplace/cxx17_return.cc b/libstdc++-v3/testsuite/23_containers/deque/modifiers/emplace/cxx17_return.cc
new file mode 100644
index 0000000..3e5da96
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/deque/modifiers/emplace/cxx17_return.cc
@@ -0,0 +1,49 @@
+// Copyright (C) 2016 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++17" }
+// { dg-do run { target c++1z } }
+
+#include <deque>
+#include <testsuite_hooks.h>
+
+using test_type = std::deque<int>;
+
+void
+test01()
+{
+  test_type x{1, 2, 3, 4};
+  test_type::reference r = x.emplace_front(0);
+  VERIFY( r == 0 );
+  VERIFY( &r == &x.front() );
+}
+
+void
+test02()
+{
+  test_type x{1, 2, 3, 4};
+  test_type::reference r = x.emplace_back(5);
+  VERIFY( r == 5 );
+  VERIFY( &r == &x.back() );
+}
+
+int
+main()
+{
+  test01();
+  test02();
+}
diff --git a/libstdc++-v3/testsuite/23_containers/forward_list/modifiers/emplace_cxx17_return.cc b/libstdc++-v3/testsuite/23_containers/forward_list/modifiers/emplace_cxx17_return.cc
new file mode 100644
index 0000000..b91c1ca
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/forward_list/modifiers/emplace_cxx17_return.cc
@@ -0,0 +1,39 @@
+// Copyright (C) 2016 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++17" }
+// { dg-do run { target c++1z } }
+
+#include <forward_list>
+#include <testsuite_hooks.h>
+
+using test_type = std::forward_list<int>;
+
+void
+test01()
+{
+  test_type x{1, 2, 3, 4};
+  test_type::reference r = x.emplace_front(0);
+  VERIFY( r == 0 );
+  VERIFY( &r == &x.front() );
+}
+
+int
+main()
+{
+  test01();
+}
diff --git a/libstdc++-v3/testsuite/23_containers/list/modifiers/emplace/cxx17_return.cc b/libstdc++-v3/testsuite/23_containers/list/modifiers/emplace/cxx17_return.cc
new file mode 100644
index 0000000..c88d8d2
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/list/modifiers/emplace/cxx17_return.cc
@@ -0,0 +1,49 @@
+// Copyright (C) 2016 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++17" }
+// { dg-do run { target c++1z } }
+
+#include <list>
+#include <testsuite_hooks.h>
+
+using test_type = std::list<int>;
+
+void
+test01()
+{
+  test_type x{1, 2, 3, 4};
+  test_type::reference r = x.emplace_front(0);
+  VERIFY( r == 0 );
+  VERIFY( &r == &x.front() );
+}
+
+void
+test02()
+{
+  test_type x{1, 2, 3, 4};
+  test_type::reference r = x.emplace_back(5);
+  VERIFY( r == 5 );
+  VERIFY( &r == &x.back() );
+}
+
+int
+main()
+{
+  test01();
+  test02();
+}
diff --git a/libstdc++-v3/testsuite/23_containers/queue/members/emplace_cxx17_return.cc b/libstdc++-v3/testsuite/23_containers/queue/members/emplace_cxx17_return.cc
new file mode 100644
index 0000000..a618e9c
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/queue/members/emplace_cxx17_return.cc
@@ -0,0 +1,39 @@
+// Copyright (C) 2016 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++17" }
+// { dg-do run { target c++1z } }
+
+#include <queue>
+#include <testsuite_hooks.h>
+
+using test_type = std::queue<int>;
+
+void
+test01()
+{
+  test_type x{ test_type::container_type{1, 2, 3, 4} };
+  test_type::reference r = x.emplace(5);
+  VERIFY( r == 5 );
+  VERIFY( &r == &x.back() );
+}
+
+int
+main()
+{
+  test01();
+}
diff --git a/libstdc++-v3/testsuite/23_containers/stack/members/emplace_cxx17_return.cc b/libstdc++-v3/testsuite/23_containers/stack/members/emplace_cxx17_return.cc
new file mode 100644
index 0000000..76964eb
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/stack/members/emplace_cxx17_return.cc
@@ -0,0 +1,39 @@
+// Copyright (C) 2016 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++17" }
+// { dg-do run { target c++1z } }
+
+#include <stack>
+#include <testsuite_hooks.h>
+
+using test_type = std::stack<int>;
+
+void
+test01()
+{
+  test_type x{ test_type::container_type{1, 2, 3, 4} };
+  test_type::reference r = x.emplace(5);
+  VERIFY( r == 5 );
+  VERIFY( &r == &x.top() );
+}
+
+int
+main()
+{
+  test01();
+}
diff --git a/libstdc++-v3/testsuite/23_containers/vector/bool/emplace_cxx17_return.cc b/libstdc++-v3/testsuite/23_containers/vector/bool/emplace_cxx17_return.cc
new file mode 100644
index 0000000..d4f70fb
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/vector/bool/emplace_cxx17_return.cc
@@ -0,0 +1,38 @@
+// Copyright (C) 2016 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++17" }
+// { dg-do run { target c++1z } }
+
+#include <vector>
+#include <testsuite_hooks.h>
+
+using test_type = std::vector<bool>;
+
+void
+test02()
+{
+  test_type x{true, true};
+  test_type::reference r = x.emplace_back(false);
+  VERIFY( r == false );
+}
+
+int
+main()
+{
+  test02();
+}
diff --git a/libstdc++-v3/testsuite/23_containers/vector/modifiers/emplace/cxx17_return.cc b/libstdc++-v3/testsuite/23_containers/vector/modifiers/emplace/cxx17_return.cc
new file mode 100644
index 0000000..9006dab
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/vector/modifiers/emplace/cxx17_return.cc
@@ -0,0 +1,39 @@
+// Copyright (C) 2016 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++17" }
+// { dg-do run { target c++1z } }
+
+#include <vector>
+#include <testsuite_hooks.h>
+
+using test_type = std::vector<int>;
+
+void
+test02()
+{
+  test_type x{1, 2, 3, 4};
+  test_type::reference r = x.emplace_back(5);
+  VERIFY( r == 5 );
+  VERIFY( &r == &x.back() );
+}
+
+int
+main()
+{
+  test02();
+}