[patch] Make std::reference_wrapper trivially copyable.

[Jonathan Wakely]

This might be required for C++17, and is beneficial anyway, so let's
change it now.

Tested x86_64-linux, committed to trunk.


commit 3b1cfc115060eb85f2a43c4bef80d25c4aefaa95
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Tue Nov 4 01:51:48 2014 +0000

    Make reference_wrapper trivially copyable.
    
        * include/std/functional (reference_wrapper): Define copy constructor
        and copy assignment as defaulted.
        * testsuite/20_util/bind/ref_neg.cc: Adjust dg-error.
        * testsuite/20_util/reference_wrapper/requirements.cc: New.

diff --git a/libstdc++-v3/include/std/functional 
b/libstdc++-v3/include/std/functional
index f8e9b54..25ec1b3 100644
--- a/libstdc++-v3/include/std/functional
+++ b/libstdc++-v3/include/std/functional
@@ -410,16 +410,10 @@ _GLIBCXX_HAS_NESTED_TYPE(result_type)
 
       reference_wrapper(_Tp&&) = delete;
 
-      reference_wrapper(const reference_wrapper<_Tp>& __inref) noexcept
-      : _M_data(__inref._M_data)
-      { }
+      reference_wrapper(const reference_wrapper&) = default;
 
       reference_wrapper&
-      operator=(const reference_wrapper<_Tp>& __inref) noexcept
-      {
-       _M_data = __inref._M_data;
-       return *this;
-      }
+      operator=(const reference_wrapper&) = default;
 
       operator _Tp&() const noexcept
       { return this->get(); }
diff --git a/libstdc++-v3/testsuite/20_util/bind/ref_neg.cc 
b/libstdc++-v3/testsuite/20_util/bind/ref_neg.cc
index 1063dd3..4e627cf 100644
--- a/libstdc++-v3/testsuite/20_util/bind/ref_neg.cc
+++ b/libstdc++-v3/testsuite/20_util/bind/ref_neg.cc
@@ -30,10 +30,10 @@ void test01()
 {
   const int dummy = 0;
   std::bind(&inc, _1)(0);               // { dg-error  "no match" }
-  // { dg-error "rvalue|const" "" { target *-*-* } 1213 }
-  // { dg-error "rvalue|const" "" { target *-*-* } 1227 }
-  // { dg-error "rvalue|const" "" { target *-*-* } 1241 }
-  // { dg-error "rvalue|const" "" { target *-*-* } 1255 }
+  // { dg-error "rvalue|const" "" { target *-*-* } 1207 }
+  // { dg-error "rvalue|const" "" { target *-*-* } 1221 }
+  // { dg-error "rvalue|const" "" { target *-*-* } 1235 }
+  // { dg-error "rvalue|const" "" { target *-*-* } 1249 }
   std::bind(&inc, std::ref(dummy))();  // { dg-error  "no match" }
 }
 
diff --git a/libstdc++-v3/testsuite/20_util/reference_wrapper/requirements.cc 
b/libstdc++-v3/testsuite/20_util/reference_wrapper/requirements.cc
new file mode 100644
index 0000000..c4d784c
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/reference_wrapper/requirements.cc
@@ -0,0 +1,32 @@
+// Copyright (C) 2014 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++11" }
+// { dg-do compile }
+
+#include <functional>
+
+struct NonTrivial
+{
+  ~NonTrivial() { }
+};
+
+using R = std::reference_wrapper<NonTrivial>;
+
+static_assert(std::is_copy_constructible<R>::value, "copy constructible");
+static_assert(std::is_copy_assignable<R>::value, "copy assignable");
+static_assert(std::is_trivially_copyable<R>::value, "trivially copyable");