@@ -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>
@@ -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
@@ -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.
@@ -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
@@ -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
@@ -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
/**
@@ -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.
@@ -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.
@@ -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
@@ -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
@@ -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>
@@ -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
new file mode 100644
@@ -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();
+}
new file mode 100644
@@ -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();
+}
new file mode 100644
@@ -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();
+}
new file mode 100644
@@ -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();
+}
new file mode 100644
@@ -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();
+}
new file mode 100644
@@ -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();
+}
new file mode 100644
@@ -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();
+}
In C++17 the emplace_front and emplace_back members return a reference. There isn't a very neat way to implement this, so it's just lots of conditional compilation. This isn't an ABI break, because these member functions are templates and so the return type is part of the mangled name. We can't apply it retroactively to older standards though, because it breaks code that is valid in C++14, such as: void f(std::vector<int>& v) { return v.emplace_back(1); } * 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. Tested powerpc64le-linux, committed to trunk. commit 8e8e806cbdd4581331364153d69d39b5765f8343 Author: Jonathan Wakely <jwakely@redhat.com> Date: Sat Oct 15 18:56:24 2016 +0100 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.