| Message ID | 543D9AE0.4090703@gmail.com |
|---|---|
| State | New |
| Headers | show |
On 14/10/14 23:51 +0200, François Dumont wrote: >Hi > > Here is a proposal to fix the issue with iterators which do not >expose lvalue references when dereferenced. I simply chose to detect >such an issue in c++11 mode thanks to the is_lvalue_reference meta >function. > >2014-10-15 François Dumont <fdumont@gcc.gnu.org> > > PR libstdc++/63500 > * include/bits/cpp_type_traits.h (__true_type): Add __value constant. > (__false_type): Likewise. > * include/debug/functions.h (__foreign_iterator_aux2): Do not check for > foreign iterators if input iterators returns rvalue reference. > * testsuite/23_containers/vector/63500.cc: New. > >Tested under Linux x86_64. > >François > >Index: include/bits/cpp_type_traits.h >=================================================================== >--- include/bits/cpp_type_traits.h (revision 216158) >+++ include/bits/cpp_type_traits.h (working copy) >@@ -79,9 +79,12 @@ > { > _GLIBCXX_BEGIN_NAMESPACE_VERSION > >- struct __true_type { }; >- struct __false_type { }; >+ struct __true_type >+ { enum { __value = 1 }; }; > >+ struct __false_type >+ { enum { __value = 0 }; }; >+ > template<bool> > struct __truth_type > { typedef __false_type __type; }; This change isn't necessary with my suggestion below. >Index: include/debug/functions.h >=================================================================== >--- include/debug/functions.h (revision 216158) >+++ include/debug/functions.h (working copy) >@@ -34,7 +34,7 @@ > // _Iter_base > #include <bits/cpp_type_traits.h> // for __is_integer > #include <bits/move.h> // for __addressof and addressof >-# include <bits/stl_function.h> // for less >+#include <bits/stl_function.h> // for less > #if __cplusplus >= 201103L > # include <type_traits> // for is_lvalue_reference and __and_ > #endif >@@ -252,8 +252,21 @@ > const _InputIterator& __other, > const _InputIterator& __other_end) > { >+#if __cplusplus >= 201103L >+ typedef std::iterator_traits<_InputIterator> _InputIteTraits; >+ typedef typename _InputIteTraits::reference _InputIteRefType; >+#endif > return __foreign_iterator_aux3(__it, __other, __other_end, >+#if __cplusplus < 201103L > _Is_contiguous_sequence<_Sequence>()); >+#else >+ typename std::conditional< >+ std::__and_<std::integral_constant< >+ bool, _Is_contiguous_sequence<_Sequence>::__value>, >+ std::is_lvalue_reference<_InputIteRefType> >::value, >+ std::__true_type, >+ std::__false_type>::type()); >+#endif > } I find this much easier to read: #if __cplusplus < 201103L typedef _Is_contiguous_sequence<_Sequence> __tag; #else using __lvalref = std::is_lvalue_reference< typename std::iterator_traits<_InputIterator>::reference>; using __contiguous = _Is_contiguous_sequence<_Sequence>; using __tag = typename std::conditional<__lvalref::value, __contiguous, std::__false_type>::type; #endif return __foreign_iterator_aux3(__it, __other, __other_end, __tag()); It only has one preprocessor condition and it avoids mismatched parentheses caused by opening the function parameter list once but closing it twice in two different branches.
Index: include/bits/cpp_type_traits.h =================================================================== --- include/bits/cpp_type_traits.h (revision 216158) +++ include/bits/cpp_type_traits.h (working copy) @@ -79,9 +79,12 @@ { _GLIBCXX_BEGIN_NAMESPACE_VERSION - struct __true_type { }; - struct __false_type { }; + struct __true_type + { enum { __value = 1 }; }; + struct __false_type + { enum { __value = 0 }; }; + template<bool> struct __truth_type { typedef __false_type __type; }; Index: include/debug/functions.h =================================================================== --- include/debug/functions.h (revision 216158) +++ include/debug/functions.h (working copy) @@ -34,7 +34,7 @@ // _Iter_base #include <bits/cpp_type_traits.h> // for __is_integer #include <bits/move.h> // for __addressof and addressof -# include <bits/stl_function.h> // for less +#include <bits/stl_function.h> // for less #if __cplusplus >= 201103L # include <type_traits> // for is_lvalue_reference and __and_ #endif @@ -252,8 +252,21 @@ const _InputIterator& __other, const _InputIterator& __other_end) { +#if __cplusplus >= 201103L + typedef std::iterator_traits<_InputIterator> _InputIteTraits; + typedef typename _InputIteTraits::reference _InputIteRefType; +#endif return __foreign_iterator_aux3(__it, __other, __other_end, +#if __cplusplus < 201103L _Is_contiguous_sequence<_Sequence>()); +#else + typename std::conditional< + std::__and_<std::integral_constant< + bool, _Is_contiguous_sequence<_Sequence>::__value>, + std::is_lvalue_reference<_InputIteRefType> >::value, + std::__true_type, + std::__false_type>::type()); +#endif } /* Handle the case where we aren't really inserting a range after all */ Index: testsuite/23_containers/vector/63500.cc =================================================================== --- testsuite/23_containers/vector/63500.cc (revision 0) +++ testsuite/23_containers/vector/63500.cc (working copy) @@ -0,0 +1,39 @@ +// -*- C++ -*- + +// 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 <memory> +#include <iterator> +#include <debug/vector> + +class Foo +{}; + +void +test01() +{ + __gnu_debug::vector<std::unique_ptr<Foo>> v; + __gnu_debug::vector<std::unique_ptr<Foo>> w; + + v.insert(end(v), + make_move_iterator(begin(w)), + make_move_iterator(end(w))); +}
Hi Here is a proposal to fix the issue with iterators which do not expose lvalue references when dereferenced. I simply chose to detect such an issue in c++11 mode thanks to the is_lvalue_reference meta function. 2014-10-15 François Dumont <fdumont@gcc.gnu.org> PR libstdc++/63500 * include/bits/cpp_type_traits.h (__true_type): Add __value constant. (__false_type): Likewise. * include/debug/functions.h (__foreign_iterator_aux2): Do not check for foreign iterators if input iterators returns rvalue reference. * testsuite/23_containers/vector/63500.cc: New. Tested under Linux x86_64. François