[libstdc++-v3] PATCH, RFC: implement is_trivially_default_constructible

diff --git a/libstdc++-v3/doc/xml/manual/status_cxx2011.xml b/libstdc++-v3/doc/xml/manual/status_cxx2011.xml
index b3c24d8..aaa4887 100644
--- a/libstdc++-v3/doc/xml/manual/status_cxx2011.xml
+++ b/libstdc++-v3/doc/xml/manual/status_cxx2011.xml
@@ -816,7 +816,7 @@  particular release.
       <entry>Type properties</entry>
       <entry>Partial</entry>
       <entry>Missing is_trivially_copyable,
-      is_trivially_constructible, is_trivially_default_constructible,
+      is_trivially_constructible,
       is_trivially_copy_constructible, is_trivially_move_constructible,
       is_trivially_assignable, is_trivially_default_assignable,
       is_trivially_copy_assignable, is_trivially_move_assignable
diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
index 4b434a6..b529ee6 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -1258,7 +1258,12 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   /// is_trivially_constructible (still unimplemented)
   
-  /// is_trivially_default_constructible (still unimplemented)
+  /// is_trivially_default_constructible
+  template<typename _Tp>
+    struct is_trivially_default_constructible
+    : public __and_<is_constructible<_Tp>, integral_constant<bool,
+			      __has_trivial_constructor(_Tp)>>::type
+    { };
 
   /// is_trivially_copy_constructible (still unimplemented)
 
diff --git a/libstdc++-v3/testsuite/20_util/is_trivially_default_constructible/value.cc b/libstdc++-v3/testsuite/20_util/is_trivially_default_constructible/value.cc
new file mode 100644
index 0000000..4d10275
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/is_trivially_default_constructible/value.cc
@@ -0,0 +1,47 @@ 
+// { dg-options "-std=gnu++11" }
+// { dg-do compile }
+//
+// 2014-03-09  Ville Voutilainen  <ville.voutilainen@gmail.com>
+//
+// 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/>.
+
+#include <type_traits>
+#include <testsuite_tr1.h>
+
+void test01()
+{
+  using std::is_trivially_default_constructible;
+  using namespace __gnu_test;
+
+  static_assert(test_category<is_trivially_default_constructible, int>(true), "");
+  static_assert(test_category<is_trivially_default_constructible, TType>(true), "");
+  static_assert(test_category<is_trivially_default_constructible, PODType>(true), "");
+
+  static_assert(test_category<is_trivially_default_constructible, NType>(false), "");
+  static_assert(test_category<is_trivially_default_constructible, SLType>(true), "");
+  static_assert(test_category<is_trivially_default_constructible, SLType>(true), "");
+  static_assert(test_category<is_trivially_default_constructible, construct::DelDef>(false), "");
+  static_assert(test_category<is_trivially_default_constructible, construct::Abstract>(false), "");
+  static_assert(test_category<is_trivially_default_constructible, construct::Ellipsis>(false), "");
+  static_assert(test_category<is_trivially_default_constructible, construct::DelEllipsis>(false), "");
+  static_assert(test_category<is_trivially_default_constructible, construct::Any>(false), "");
+  static_assert(test_category<is_trivially_default_constructible, construct::DelCopy>(false), "");
+  static_assert(test_category<is_trivially_default_constructible, construct::DelDtor>(false), "");
+  static_assert(test_category<is_trivially_default_constructible, construct::Nontrivial>(false), "");
+
+}