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re PR libstdc++/53648 ([C++11] nested empty tuples) 

PR libstdc++/53648
	* include/std/tuple (__empty_not_final): Do not use EBO for tuples.
	* testsuite/20_util/tuple/53648.cc: New.
	* testsuite/20_util/uses_allocator/cons_neg.cc: Adjust dg-error line
	number.

From-SVN: r188636
This commit is contained in:
Jonathan Wakely 2012-06-14 22:07:33 +00:00 committed by Jonathan Wakely
parent d8ac8ab82d
commit 5c8dd62a1b
4 changed files with 64 additions and 3 deletions
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8
libstdc++-v3/ChangeLog
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@ -1,3 +1,11 @@
2012-06-14 Jonathan Wakely <jwakely.gcc@gmail.com>
PR libstdc++/53648
* include/std/tuple (__empty_not_final): Do not use EBO for tuples.
* testsuite/20_util/tuple/53648.cc: New.
* testsuite/20_util/uses_allocator/cons_neg.cc: Adjust dg-error line
number.
2012-06-14 Jonathan Wakely <jwakely.gcc@gmail.com>
* doc/xml/manual/status_cxx2011.xml: Correct C++11 status table.

13
libstdc++-v3/include/std/tuple
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@ -1,6 +1,7 @@
// <tuple> -*- C++ -*-
// Copyright (C) 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
// Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012
// 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
@ -201,10 +202,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
void _M_swap(_Tuple_impl&) noexcept { /* no-op */ }
};
template<typename _Tp>
struct __is_empty_non_tuple : is_empty<_Tp> { };
// Using EBO for elements that are tuples causes ambiguous base errors.
template<typename _El0, typename... _El>
struct __is_empty_non_tuple<tuple<_El0, _El...>> : false_type { };
// Use the Empty Base-class Optimization for empty, non-final types.
template<typename _Tp>
using __empty_not_final
= typename conditional<__is_final(_Tp), false_type, is_empty<_Tp>>::type;
= typename conditional<__is_final(_Tp), false_type,
__is_empty_non_tuple<_Tp>>::type;
/**
* Recursive tuple implementation. Here we store the @c Head element

44
libstdc++-v3/testsuite/20_util/tuple/53648.cc Normal file
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@ -0,0 +1,44 @@
// { dg-options "-std=gnu++0x" }
// { dg-do compile }
// Copyright (C) 2012 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/>.
// libstdc++/53648
#include <tuple>
#include <type_traits>
using std::tuple;
struct A { };
template class tuple<tuple<>>;
template class tuple<tuple<tuple<>>>;
template class tuple<A, tuple<A, tuple<A, tuple<A>>>>;
template class tuple<tuple<tuple<A, A>, A>, A>;
// Verify the following QoI properties are preserved
static_assert( std::is_empty<tuple<>>::value, "tuple<> is empty" );
static_assert( std::is_empty<tuple<tuple<>>>::value,
"tuple<tuple<>> is empty" );
static_assert( sizeof(tuple<char, tuple<>>) == sizeof(char),
"tuple<> is eligible for EBO" );

2
libstdc++-v3/testsuite/20_util/uses_allocator/cons_neg.cc
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@ -44,4 +44,4 @@ void test01()
tuple<Type> t(allocator_arg, a, 1);
}
// { dg-error "no matching function" "" { target *-*-* } 112 }
// { dg-error "no matching function" "" { target *-*-* } 113 }