[v3] Add move_if_noexcept

[v3] Add move_if_noexcept

[Paolo Carlini]

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Hi,

tested x86_64-linux, committed to mainline.

Thanks,
Paolo.

///////////////////

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2011-04-27  Paolo Carlini  <paolo.carlini@oracle.com>

	* include/bits/move.h (move_if_noexcept): Add.
	* testsuite/20_util/move_if_noexcept/requirements/
	explicit_instantiation.cc: New.
	* testsuite/20_util/move_if_noexcept/1.cc: Likewise.


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Index: include/bits/move.h
===================================================================
--- include/bits/move.h	(revision 173043)
+++ include/bits/move.h	(working copy)
@@ -1,6 +1,6 @@
 // Move, forward and identity for C++0x + swap -*- C++ -*-
 
-// Copyright (C) 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
+// Copyright (C) 2007, 2008, 2009, 2010, 2011 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
@@ -73,7 +73,7 @@
 
   /**
    *  @brief Move a value.
-   *  @ingroup mutating_algorithms
+   *  @ingroup utilities
    *  @param  __t  A thing of arbitrary type.
    *  @return Same, moved.
   */
@@ -82,12 +82,27 @@
     move(_Tp&& __t)
     { return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); }
 
+  /**
+   *  @brief Move unless it could throw and the type is copyable.
+   *  @ingroup utilities
+   *  @param  __x  A thing of arbitrary type.
+   *  @return Same, possibly moved.
+   */
+  template<typename _Tp>
+    inline typename
+    conditional<(!is_nothrow_move_constructible<_Tp>::value
+		 && is_copy_constructible<_Tp>::value),
+                const _Tp&, _Tp&&>::type
+    move_if_noexcept(_Tp& __x) noexcept
+    { return std::move(__x); }
+
   /// declval, from type_traits.
 
   /**
    *  @brief Returns the actual address of the object or function
    *         referenced by r, even in the presence of an overloaded
    *         operator&.
+   *  @ingroup utilities
    *  @param  __r  Reference to an object or function.
    *  @return   The actual address.
   */
@@ -112,7 +127,7 @@
 
   /**
    *  @brief Swaps two values.
-   *  @ingroup mutating_algorithms
+   *  @ingroup utilities
    *  @param  __a  A thing of arbitrary type.
    *  @param  __b  Another thing of arbitrary type.
    *  @return   Nothing.
Index: testsuite/20_util/move_if_noexcept/requirements/explicit_instantiation.cc
===================================================================
--- testsuite/20_util/move_if_noexcept/requirements/explicit_instantiation.cc	(revision 0)
+++ testsuite/20_util/move_if_noexcept/requirements/explicit_instantiation.cc	(revision 0)
@@ -0,0 +1,36 @@
+// { dg-options "-std=gnu++0x" }
+// { dg-do compile }
+
+// 2011-04-27  Paolo Carlini  <paolo.carlini@oracle.com>
+
+// Copyright (C) 2011 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/>.
+
+// NB: This file is for testing utility with NO OTHER INCLUDES.
+
+#include <utility>
+
+namespace std
+{
+  typedef short test_type;
+  
+  template
+  std::conditional<(!std::is_nothrow_move_constructible<test_type>::value
+		    && std::is_copy_constructible<test_type>::value),
+		   const test_type&, test_type&&>::type
+  move_if_noexcept(test_type&);
+}
Index: testsuite/20_util/move_if_noexcept/1.cc
===================================================================
--- testsuite/20_util/move_if_noexcept/1.cc	(revision 0)
+++ testsuite/20_util/move_if_noexcept/1.cc	(revision 0)
@@ -0,0 +1,119 @@
+// { dg-options "-std=gnu++0x" }
+
+// 2011-04-27  Paolo Carlini  <paolo.carlini@oracle.com>
+//
+// Copyright (C) 2011 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 <utility>
+#include <testsuite_hooks.h>
+
+struct noexcept_move_copy
+{
+  noexcept_move_copy()
+  : status(true)
+  { };
+
+  noexcept_move_copy(noexcept_move_copy&& r) noexcept
+  { r.status = false; };
+
+  noexcept_move_copy(const noexcept_move_copy&) = default;
+
+  operator bool() { return status; }
+
+private:
+  bool status;
+};
+
+struct noexcept_move_no_copy
+{
+  noexcept_move_no_copy()
+  : status(true)
+  { };
+
+  noexcept_move_no_copy(noexcept_move_no_copy&& r) noexcept
+  { r.status = false; };
+
+  noexcept_move_no_copy(const noexcept_move_no_copy&) = delete;
+
+  operator bool() { return status; }
+
+private:
+  bool status;
+};
+
+struct except_move_copy
+{
+  except_move_copy()
+  : status(true)
+  { };
+
+  except_move_copy(except_move_copy&& r) noexcept(false)
+  { r.status = false; };
+
+  except_move_copy(const except_move_copy&) = default;
+
+  operator bool() { return status; }
+
+private:
+  bool status;
+};
+
+struct except_move_no_copy
+{
+  except_move_no_copy()
+  : status(true)
+  { };
+
+  except_move_no_copy(except_move_no_copy&& r) noexcept(false)
+  { r.status = false; };
+
+  except_move_no_copy(const except_move_no_copy&) = delete;
+
+  operator bool() { return status; }
+
+private:
+  bool status;
+};
+
+void
+test01()
+{
+  bool test __attribute__((unused)) = true;
+
+  noexcept_move_copy nemc1;
+  auto nemc2 __attribute__((unused)) = std::move_if_noexcept(nemc1);
+  VERIFY( nemc1 == false );
+
+  noexcept_move_no_copy nemnc1;
+  auto nemnc2 __attribute__((unused)) = std::move_if_noexcept(nemnc1);
+  VERIFY( nemnc1 == false );
+
+  except_move_copy emc1;
+  auto emc2 __attribute__((unused)) = std::move_if_noexcept(emc1);
+  VERIFY( emc1 == true );
+
+  except_move_no_copy emnc1;
+  auto emnc2 __attribute__((unused)) = std::move_if_noexcept(emnc1);
+  VERIFY( emnc1 == false );
+}
+
+int main()
+{
+  test01();
+  return 0;
+}