Subject: [Boost-bugs] [Boost C++ Libraries] #12895: VS 2012: zip_iterator dereference causes a compiler error
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2017-03-10 21:26:44
#12895: VS 2012: zip_iterator dereference causes a compiler error
-------------------------------+------------------------------
Reporter: daniel.kruegler@… | Owner: jeffrey.hellrung
Type: Bugs | Status: new
Milestone: To Be Determined | Component: iterator
Version: Boost 1.63.0 | Severity: Problem
Keywords: |
-------------------------------+------------------------------
Using Visual Studio 2012 (vc110), any direct or indirect usage of the
dereference operation of zip_iterator produces now a compiler error, a
simple reproducer is the following example:
{{{
#include "boost/iterator/zip_iterator.hpp"
int main()
{
typedef boost::tuple<char*, char*> iterators_t;
char chars[] = "abc";
iterators_t iters(chars + 0, chars + 3);
boost::iterators::zip_iterator<iterators_t> zip(iters);
*zip;
}
}}}
which results in the following compiler output:
{{{
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(364): error C2825: '_Iter': must be a class or
namespace when followed by '::'
1>
c:\projects\thirdparty\boost_1_63_0\boost\iterator\iterator_traits.hpp(28)
: see reference to class template instantiation
'std::iterator_traits<_Iter>' being compiled
1> with
1> [
1> _Iter=char *const
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\iterator\zip_iterator.hpp(90) :
see reference to class template instantiation
'boost::iterators::iterator_reference<Iterator>' being compiled
1> with
1> [
1> Iterator=char *const
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\utility\result_of.hpp(190) : see
reference to class template instantiation
'boost::iterators::detail::dereference_iterator::result<<unnamed-symbol>>'
being compiled
1> with
1> [
1> <unnamed-
symbol>=boost::iterators::detail::dereference_iterator (char *const &)
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\utility\result_of.hpp(197) : see
reference to class template instantiation
'boost::detail::result_of_nested_result<F,FArgs>' being compiled
1> with
1> [
1> F=boost::iterators::detail::dereference_iterator,
1> FArgs=boost::iterators::detail::dereference_iterator (char
*const &)
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\utility\detail\result_of_iterate.hpp(37)
: see reference to class template instantiation
'boost::detail::tr1_result_of_impl<F,FArgs,HasResultType>' being compiled
1> with
1> [
1> F=boost::iterators::detail::dereference_iterator,
1> FArgs=boost::iterators::detail::dereference_iterator (char
*const &),
1> HasResultType=false
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\utility\detail\result_of_iterate.hpp(160)
: see reference to class template instantiation 'boost::tr1_result_of<F>'
being compiled
1> with
1> [
1> F=boost::iterators::detail::dereference_iterator (char
*const &)
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\fusion\view\transform_view\detail\apply_transform_result.hpp(31)
: see reference to class template instantiation 'boost::result_of<F>'
being compiled
1> with
1> [
1> F=boost::iterators::detail::dereference_iterator (char
*const &)
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\mpl\aux_\preprocessed\plain\apply_wrap.hpp(39)
: see reference to class template instantiation
'boost::fusion::detail::apply_transform_result<F>::apply<T0>' being
compiled
1> with
1> [
1> F=boost::iterators::detail::dereference_iterator,
1> T0=char *const &
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\mpl\aux_\preprocessed\plain\apply.hpp(43)
: see reference to class template instantiation
'boost::mpl::apply_wrap1<F,T1>' being compiled
1> with
1> [
1>
F=boost::fusion::detail::apply_transform_result<boost::iterators::detail::dereference_iterator>,
1> T1=char *const &
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\mpl\aux_\preprocessed\plain\apply.hpp(51)
: see reference to class template instantiation 'boost::mpl::apply1<F,T1>'
being compiled
1> with
1> [
1>
F=boost::fusion::detail::apply_transform_result<boost::iterators::detail::dereference_iterator>,
1> T1=char *const &
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\fusion\view\transform_view\detail\deref_impl.hpp(38)
: see reference to class template instantiation 'boost::mpl::apply<F,T1>'
being compiled
1> with
1> [
1>
F=boost::fusion::detail::apply_transform_result<boost::iterators::detail::dereference_iterator>,
1> T1=char *const &
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\fusion\iterator\deref.hpp(54) :
see reference to class template instantiation
'boost::fusion::extension::deref_impl<boost::fusion::transform_view_iterator_tag>::apply<Iterator>'
being compiled
1> with
1> [
1>
Iterator=boost::fusion::transform_view_iterator<boost::fusion::boost_tuple_iterator<const
iterators_t>,boost::iterators::detail::dereference_iterator>
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\fusion\adapted\boost_tuple\detail\build_cons.hpp(53)
: see reference to class template instantiation
'boost::fusion::result_of::deref<Iterator>' being compiled
1> with
1> [
1>
Iterator=boost::fusion::transform_view_iterator<boost::fusion::boost_tuple_iterator<const
iterators_t>,boost::iterators::detail::dereference_iterator>
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\fusion\adapted\boost_tuple\detail\build_cons.hpp(52)
: while compiling class template member function
'boost::tuples::cons<HT,TT>
boost::fusion::detail::build_tuple_cons<First,Last>::call(const First
&,const Last &)'
1> with
1> [
1> HT=char &,
1> TT=boost::tuples::cons<char
&,boost::fusion::detail::build_tuple_cons<boost::fusion::single_view_iterator<const
boost::fusion::single_view<char
&>,boost::mpl::int_<1>>,boost::fusion::single_view_iterator<const
boost::fusion::single_view<char &>,boost::mpl::int_<1>>>::type>,
1>
First=boost::fusion::transform_view_iterator<boost::fusion::boost_tuple_iterator<const
iterators_t>,boost::iterators::detail::dereference_iterator>,
1>
Last=boost::fusion::transform_view_iterator<boost::fusion::boost_tuple_iterator<const
boost::tuples::null_type>,boost::iterators::detail::dereference_iterator>
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\fusion\adapted\boost_tuple\detail\convert_impl.hpp(43)
: see reference to function template instantiation
'boost::tuples::cons<HT,TT>
boost::fusion::detail::build_tuple_cons<First,Last>::call(const First
&,const Last &)' being compiled
1> with
1> [
1> HT=char &,
1> TT=boost::tuples::cons<char
&,boost::fusion::detail::build_tuple_cons<boost::fusion::single_view_iterator<const
boost::fusion::single_view<char
&>,boost::mpl::int_<1>>,boost::fusion::single_view_iterator<const
boost::fusion::single_view<char &>,boost::mpl::int_<1>>>::type>,
1>
First=boost::fusion::transform_view_iterator<boost::fusion::boost_tuple_iterator<const
iterators_t>,boost::iterators::detail::dereference_iterator>,
1>
Last=boost::fusion::transform_view_iterator<boost::fusion::boost_tuple_iterator<const
boost::tuples::null_type>,boost::iterators::detail::dereference_iterator>
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\fusion\adapted\boost_tuple\detail\convert_impl.hpp(37)
: see reference to class template instantiation
'boost::fusion::detail::build_tuple_cons<First,Last>' being compiled
1> with
1> [
1>
First=boost::fusion::transform_view_iterator<boost::fusion::boost_tuple_iterator<const
iterators_t>,boost::iterators::detail::dereference_iterator>,
1>
Last=boost::fusion::transform_view_iterator<boost::fusion::boost_tuple_iterator<const
boost::tuples::null_type>,boost::iterators::detail::dereference_iterator>
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\fusion\sequence\convert.hpp(37)
: see reference to class template instantiation
'boost::fusion::extension::convert_impl<boost::fusion::boost_tuple_tag>::apply<Sequence>'
being compiled
1> with
1> [
1> Sequence=const boost::fusion::transform_view<const
iterators_t,boost::iterators::detail::dereference_iterator>
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\iterator\zip_iterator.hpp(214) :
see reference to class template instantiation
'boost::fusion::result_of::convert<Tag,Sequence>' being compiled
1> with
1> [
1> Tag=tag,
1> Sequence=const boost::fusion::transform_view<const
iterators_t,boost::iterators::detail::dereference_iterator>
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\iterator\zip_iterator.hpp(289) :
see reference to function template instantiation 'reference
boost::iterators::detail::converter<reference>::call<boost::fusion::transform_view<Sequence1,Sequence2>>(Seq)'
being compiled
1> with
1> [
1> reference=reference,
1> Sequence1=const iterators_t,
1> Sequence2=boost::iterators::detail::dereference_iterator,
1> Seq=boost::fusion::transform_view<const
iterators_t,boost::iterators::detail::dereference_iterator>
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\iterator\zip_iterator.hpp(289) :
see reference to function template instantiation 'reference
boost::iterators::detail::converter<reference>::call<boost::fusion::transform_view<Sequence1,Sequence2>>(Seq)'
being compiled
1> with
1> [
1> reference=reference,
1> Sequence1=const iterators_t,
1> Sequence2=boost::iterators::detail::dereference_iterator,
1> Seq=boost::fusion::transform_view<const
iterators_t,boost::iterators::detail::dereference_iterator>
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\iterator\zip_iterator.hpp(284) :
while compiling class template member function 'boost::tuples::cons<HT,TT>
boost::iterators::zip_iterator<IteratorTuple>::dereference(void) const'
1> with
1> [
1> HT=char &,
1> TT=boost::tuples::cons<char
&,boost::fusion::detail::build_tuple_cons<boost::fusion::single_view_iterator<const
boost::fusion::single_view<char
&>,boost::mpl::int_<1>>,boost::fusion::single_view_iterator<const
boost::fusion::single_view<char &>,boost::mpl::int_<1>>>::type>,
1> IteratorTuple=iterators_t
1> ]
1>
c:\projects\thirdparty\boost_1_63_0\boost\iterator\iterator_facade.hpp(549)
: see reference to function template instantiation
'boost::tuples::cons<HT,TT>
boost::iterators::zip_iterator<IteratorTuple>::dereference(void) const'
being compiled
1> with
1> [
1> HT=char &,
1> TT=boost::tuples::cons<char
&,boost::fusion::detail::build_tuple_cons<boost::fusion::single_view_iterator<const
boost::fusion::single_view<char
&>,boost::mpl::int_<1>>,boost::fusion::single_view_iterator<const
boost::fusion::single_view<char &>,boost::mpl::int_<1>>>::type>,
1> IteratorTuple=iterators_t
1> ]
1> h:\develop\cpp\c++0x\vssandbox - 2011\main.cpp(8) : see
reference to class template instantiation
'boost::iterators::zip_iterator<IteratorTuple>' being compiled
1> with
1> [
1> IteratorTuple=iterators_t
1> ]
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(364): error C2039: 'iterator_category' : is not a
member of '`global namespace''
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(364): error C2146: syntax error : missing ';'
before identifier 'iterator_category'
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(364): error C2602:
'std::iterator_traits<_Iter>::iterator_category' is not a member of a base
class of 'std::iterator_traits<_Iter>'
1> with
1> [
1> _Iter=char *const
1> ]
1> c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(364) : see declaration of
'std::iterator_traits<_Iter>::iterator_category'
1> with
1> [
1> _Iter=char *const
1> ]
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(364): error C2868:
'std::iterator_traits<_Iter>::iterator_category' : illegal syntax for
using-declaration; expected qualified-name
1> with
1> [
1> _Iter=char *const
1> ]
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(365): error C2825: '_Iter': must be a class or
namespace when followed by '::'
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(365): error C2039: 'value_type' : is not a member
of '`global namespace''
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(365): error C2146: syntax error : missing ';'
before identifier 'value_type'
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(365): error C2602:
'std::iterator_traits<_Iter>::value_type' is not a member of a base class
of 'std::iterator_traits<_Iter>'
1> with
1> [
1> _Iter=char *const
1> ]
1> c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(365) : see declaration of
'std::iterator_traits<_Iter>::value_type'
1> with
1> [
1> _Iter=char *const
1> ]
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(365): error C2868:
'std::iterator_traits<_Iter>::value_type' : illegal syntax for using-
declaration; expected qualified-name
1> with
1> [
1> _Iter=char *const
1> ]
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(366): error C2825: '_Iter': must be a class or
namespace when followed by '::'
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(366): error C2039: 'difference_type' : is not a
member of '`global namespace''
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(366): error C2146: syntax error : missing ';'
before identifier 'difference_type'
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(366): error C2602:
'std::iterator_traits<_Iter>::difference_type' is not a member of a base
class of 'std::iterator_traits<_Iter>'
1> with
1> [
1> _Iter=char *const
1> ]
1> c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(366) : see declaration of
'std::iterator_traits<_Iter>::difference_type'
1> with
1> [
1> _Iter=char *const
1> ]
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(366): error C2868:
'std::iterator_traits<_Iter>::difference_type' : illegal syntax for using-
declaration; expected qualified-name
1> with
1> [
1> _Iter=char *const
1> ]
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(368): error C2825: '_Iter': must be a class or
namespace when followed by '::'
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(368): error C2039: 'pointer' : is not a member of
'`global namespace''
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(368): error C2146: syntax error : missing ';'
before identifier 'pointer'
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(368): error C2602:
'std::iterator_traits<_Iter>::pointer' is not a member of a base class of
'std::iterator_traits<_Iter>'
1> with
1> [
1> _Iter=char *const
1> ]
1> c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(368) : see declaration of
'std::iterator_traits<_Iter>::pointer'
1> with
1> [
1> _Iter=char *const
1> ]
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(368): error C2868:
'std::iterator_traits<_Iter>::pointer' : illegal syntax for using-
declaration; expected qualified-name
1> with
1> [
1> _Iter=char *const
1> ]
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(369): error C2825: '_Iter': must be a class or
namespace when followed by '::'
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(369): error C2039: 'reference' : is not a member
of '`global namespace''
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(369): error C2146: syntax error : missing ';'
before identifier 'reference'
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(369): error C2602:
'std::iterator_traits<_Iter>::reference' is not a member of a base class
of 'std::iterator_traits<_Iter>'
1> with
1> [
1> _Iter=char *const
1> ]
1> c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(369) : see declaration of
'std::iterator_traits<_Iter>::reference'
1> with
1> [
1> _Iter=char *const
1> ]
1>c:\program files (x86)\microsoft visual studio
11.0\vc\include\xutility(369): error C2868:
'std::iterator_traits<_Iter>::reference' : illegal syntax for using-
declaration; expected qualified-name
1> with
1> [
1> _Iter=char *const
1> ]
1>c:\projects\thirdparty\boost_1_63_0\boost\fusion\adapted\boost_tuple\detail\build_cons.hpp(53):
error C2440: 'initializing' : cannot convert from 'char *const ' to 'char
&'
========== Rebuild All: 0 succeeded, 1 failed, 0 skipped ==========
}}}
The problem seems rather severe to me and may occur even though the user-
code didn't actually use zip_iterator directly. In fact I became aware of
the problem when a colleague asked me why the following code would no
longer be accepted when we switched from Boost 1.57 to Boost 1.63:
{{{
#include "boost/range/combine.hpp"
int main()
{
int a[] = { 1, 2, 3 };
int b[] = { 4, 5, 6 };
for(const auto& p : boost::combine(a, b))
{
}
}
}}}
According to my not fully completed analysis, the problem is caused,
because the current implementation of zip_iterator::dereference relies on
a recently introduced feature of std::iterator_traits being now sfinae-
friendly (See LWG issue 2408), which is not the case in the VS 2012
Standard Library. This assumption gets support by the fact that both VS
2015 and VS 2017 accept the code (And both compiler's Standard Libraries
provide sfinae-friendly iterator_traits).
-- Ticket URL: <https://svn.boost.org/trac/boost/ticket/12895> Boost C++ Libraries <http://www.boost.org/> Boost provides free peer-reviewed portable C++ source libraries.
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