[mpl] possible regression compiling with Visual C++

[Edd Dawson-3]

Hi folks,

The following code compiles fine against Boost 1.34.1 and 1.35.0, but apparently
not anything later. I've tried 1.36.0 and 1.39.0.

I'm compiling with Microsoft's Visual C++ 2005 and 2009 compilers (the express
editions if it matters).


#include <boost/mpl/remove.hpp>
#include <boost/mpl/vector.hpp>
#include <boost/preprocessor/repetition/enum_params.hpp>
#include <boost/preprocessor/repetition/enum_params_with_a_default.hpp>

template<BOOST_PP_ENUM_PARAMS_WITH_A_DEFAULT(BOOST_MPL_LIMIT_VECTOR_SIZE,
typename T, void)>
struct X
{
     typedef typename
         boost::mpl::vector<BOOST_PP_ENUM_PARAMS(BOOST_MPL_LIMIT_VECTOR_SIZE,
T)>::type
         template_parameters; // mpl::vector of template parameters

     typedef typename boost::mpl::remove
     <
         template_parameters,
         void
     >
     ::type template_parameters_no_voids; // voids removed
};

int main()
{
     X<int> x;
     return 0;
}


The error messages using Boost 1.39.0 and Visual C++ 2005:

mpl_regression.cpp
M:\libs\boost\1.39.0\boost/mpl/aux_/push_back_impl.hpp(45) : error C2664:
'boost::mpl::assertion_failed' : cannot convert parameter 1 from
'boost::mpl::failed ************(__thiscall
boost::mpl::push_back_impl<Tag>::apply<Sequence,T>::REQUESTED_PUSH_BACK_SPECIALIZATION_FOR_SEQUENCE_DOES_NOT_EXIST::*
***********)(Sequence)' to 'boost::mpl::assert<false>::type'
         with
         [
             Tag=boost::mpl::aux::vector_tag<20>,
 
Sequence=boost::mpl::vector20<int,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void>,
             T=boost::mpl::has_push_back_impl<boost::mpl::aux::vector_tag<20>>
         ]
         No constructor could take the source type, or constructor overload
resolution was ambiguous
         M:\libs\boost\1.39.0\boost/mpl/push_back.hpp(32) : see reference to
class template instantiation
'boost::mpl::push_back_impl<Tag>::apply<Sequence,T>' being compiled
         with
         [
             Tag=boost::mpl::aux::vector_tag<20>,
 
Sequence=boost::mpl::vector20<int,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void>,
             T=boost::mpl::has_push_back_impl<boost::mpl::aux::vector_tag<20>>
         ]
         M:\libs\boost\1.39.0\boost/mpl/aux_/has_type.hpp(20) : see reference to
class template instantiation 'boost::mpl::push_back<Sequence,T>' being compiled
         with
         [
 
Sequence=boost::mpl::vector20<int,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void>,
             T=boost::mpl::has_push_back_impl<boost::mpl::aux::vector_tag<20>>
         ]
         M:\libs\boost\1.39.0\boost/mpl/aux_/push_back_impl.hpp(55) : see
reference to class template instantiation 'boost::mpl::aux::has_type<T>' being
compiled
         with
         [
 
T=boost::mpl::push_back<boost::mpl::vector20<int,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void>,boost::mpl::has_push_back_impl<boost::mpl::aux::vector_tag<20>>>
         ]
         M:\libs\boost\1.39.0\boost/mpl/push_back.hpp(43) : see reference to
class template instantiation 'boost::mpl::has_push_back_impl<Tag>::apply<Seq>'
being compiled
         with
         [
             Tag=boost::mpl::aux::vector_tag<20>,
 
Seq=boost::mpl::vector20<int,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void>
         ]
         M:\libs\boost\1.39.0\boost/mpl/if.hpp(63) : see reference to class
template instantiation 'boost::mpl::has_push_back<Sequence>' being compiled
         with
         [
 
Sequence=boost::mpl::vector20<int,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void>
         ]
         M:\libs\boost\1.39.0\boost/mpl/remove.hpp(48) : see reference to class
template instantiation 'boost::mpl::if_<T1,T2,T3>' being compiled
         with
         [
 
T1=boost::mpl::has_push_back<boost::mpl::vector20<int,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void>>,
 
T2=boost::mpl::aux::remove_impl<boost::mpl::vector20<int,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void>,void,boost::mpl::back_inserter<boost::mpl::clear_impl<boost::mpl::aux::vector_tag<20>>::apply<boost::mpl::vector20<int,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void>>::type>>,
 
T3=boost::mpl::aux::reverse_remove_impl<boost::mpl::vector20<int,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void>,void,boost::mpl::front_inserter<boost::mpl::clear_impl<boost::mpl::aux::vector_tag<20>>::apply<boost::mpl::vector20<int,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void>>::type>>
         ]
         mpl_regression.cpp(18) : see reference to class template instantiation
'boost::mpl::remove<P1,P2>' being compiled
         with
         [
 
P1=boost::mpl::vector20<int,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void>,
             P2=void
         ]
         mpl_regression.cpp(23) : see reference to class template instantiation
'X<T0>' being compiled
         with
         [
             T0=int
         ]
M:\libs\boost\1.39.0\boost/mpl/aux_/push_back_impl.hpp(45) : error C2866:
'boost::mpl::push_back_impl<Tag>::apply<Sequence,T>::mpl_assertion_in_line_6' :
a const static data member of a managed type must be initialized at the point of
declaration
         with
         [
             Tag=boost::mpl::aux::vector_tag<20>,
 
Sequence=boost::mpl::vector20<int,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void,void>,
             T=boost::mpl::has_push_back_impl<boost::mpl::aux::vector_tag<20>>
         ]


Is this a problem with more recent versions of Boost, or am I doing something
wrong?

It looks like it's complaining because an mpl::vector of maximal static size
doesn't implement push_back, but it surely shouldn't need to for a remove operation?

Kind regards,

Edd

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[Steven Watanabe-4]

AMDG

Edd Dawson wrote:

> The following code compiles fine against Boost 1.34.1 and 1.35.0, but
> apparently not anything later. I've tried 1.36.0 and 1.39.0.
>
> I'm compiling with Microsoft's Visual C++ 2005 and 2009 compilers (the
> express editions if it matters).
>
>
> #include <boost/mpl/remove.hpp>
> #include <boost/mpl/vector.hpp>
> #include <boost/preprocessor/repetition/enum_params.hpp>
> #include <boost/preprocessor/repetition/enum_params_with_a_default.hpp>
>
> template<BOOST_PP_ENUM_PARAMS_WITH_A_DEFAULT(BOOST_MPL_LIMIT_VECTOR_SIZE,
> typename T, void)>
> struct X
> {
>     typedef typename
>        
> boost::mpl::vector<BOOST_PP_ENUM_PARAMS(BOOST_MPL_LIMIT_VECTOR_SIZE,
> T)>::type
>         template_parameters; // mpl::vector of template parameters
>
>     typedef typename boost::mpl::remove
>     <
>         template_parameters,
>         void
>     >
>     ::type template_parameters_no_voids; // voids removed
> };
>
> int main()
> {
>     X<int> x;
>     return 0;
> }
>
>
> The error messages using Boost 1.39.0 and Visual C++ 2005:
>
> <snip>
>
> Is this a problem with more recent versions of Boost, or am I doing
> something wrong?
>
> It looks like it's complaining because an mpl::vector of maximal
> static size doesn't implement push_back, but it surely shouldn't need
> to for a remove operation?

The first problem is that remove is implemented by calling either
push_back or push_front on an empty sequence.  The
error occurs when remove is deciding whether it can use
push_back.  inserter_algorithm.hpp.patch fixes the problem
by calling clear on the argument before running the test.

The second problem is that has_push_back is broken.
push_back_impl.hpp.patch should fix it.

In Christ,
Steven Watanabe


Index: boost/mpl/aux_/inserter_algorithm.hpp
===================================================================
--- boost/mpl/aux_/inserter_algorithm.hpp (revision 54788)
+++ boost/mpl/aux_/inserter_algorithm.hpp (working copy)
@@ -49,7 +49,7 @@
       BOOST_MPL_PP_PARAMS(BOOST_PP_DEC(arity), typename P) \
     > \
 struct name< BOOST_MPL_PP_PARAMS(BOOST_PP_DEC(arity), P),na > \
-    : if_< has_push_back<P1> \
+    : if_< has_push_back< typename clear<P1>::type> \
         , aux::name##_impl< \
               BOOST_MPL_PP_PARAMS(BOOST_PP_DEC(arity), P) \
             , back_inserter< typename clear<P1>::type > \

Index: boost/mpl/aux_/push_back_impl.hpp
===================================================================
--- boost/mpl/aux_/push_back_impl.hpp (revision 54788)
+++ boost/mpl/aux_/push_back_impl.hpp (working copy)
@@ -25,8 +25,7 @@
 
 namespace boost { namespace mpl {
 
-template< typename Tag >
-struct has_push_back_impl;
+struct has_push_back_arg;
 
 // agurt 05/feb/04: no default implementation; the stub definition is needed
 // to enable the default 'has_push_back' implementation below
@@ -39,7 +38,7 @@
         // if you've got an assert here, you are requesting a 'push_back'
         // specialization that doesn't exist.
         BOOST_MPL_ASSERT_MSG(
-              ( boost::is_same< T, has_push_back_impl<T> >::value )
+              ( boost::is_same< T, has_push_back_arg >::value )
             , REQUESTED_PUSH_BACK_SPECIALIZATION_FOR_SEQUENCE_DOES_NOT_EXIST
             , ( Sequence )
             );
@@ -51,13 +50,13 @@
 {
     template< typename Seq > struct apply
 #if !defined(BOOST_MPL_CFG_NO_NESTED_FORWARDING)
-        : aux::has_type< push_back< Seq, has_push_back_impl<Tag> > >
+        : aux::has_type< push_back< Seq, has_push_back_arg > >
     {
 #else
     {
-        typedef aux::has_type< push_back< Seq, has_push_back_impl<Tag> > > type;
+        typedef aux::has_type< push_back< Seq, has_push_back_arg > > type;
         BOOST_STATIC_CONSTANT(bool, value =
-              (aux::has_type< push_back< Seq, has_push_back_impl<Tag> > >::value)
+              (aux::has_type< push_back< Seq, has_push_back_arg > >::value)
             );
 #endif
     };

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[Edd Dawson-3]

Steven Watanabe wrote:

> The first problem is that remove is implemented by calling either
> push_back or push_front on an empty sequence.  The
> error occurs when remove is deciding whether it can use
> push_back.  inserter_algorithm.hpp.patch fixes the problem
> by calling clear on the argument before running the test.
>
> The second problem is that has_push_back is broken.
> push_back_impl.hpp.patch should fix it.

Thanks very much, Steven. I guess I should file a bug report with your patches
attached?

Kind regards,

Edd

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[David Abrahams-3]

on Wed Jul 08 2009, Edd Dawson <lists-AT-mr-edd.co.uk> wrote:

> Steven Watanabe wrote:
>
>> The first problem is that remove is implemented by calling either
>> push_back or push_front on an empty sequence.  The
>> error occurs when remove is deciding whether it can use
>> push_back.  inserter_algorithm.hpp.patch fixes the problem
>> by calling clear on the argument before running the test.
>>
>> The second problem is that has_push_back is broken.
>> push_back_impl.hpp.patch should fix it.
>
> Thanks very much, Steven. I guess I should file a bug report with your patches
> attached?

Steven, you can go ahead and apply these patches as far as I'm
concerned.

--
Dave Abrahams
BoostPro Computing
http://www.boostpro.com

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[Aleksey Gurtovoy]

On Tue, 14 Jul 2009 02:19:19 -0500, David Abrahams <dave@...>  
wrote:

> Steven, you can go ahead and apply these patches as far as I'm
> concerned.

Yep, please feel free to commit these, they look good to me as well.

TIA,
--
Aleksey Gurtovoy
MetaCommunications Engineering

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[Steven Watanabe-4]

AMDG

Aleksey Gurtovoy wrote:
> On Tue, 14 Jul 2009 02:19:19 -0500, David Abrahams <dave@...>
> wrote:
>
>> Steven, you can go ahead and apply these patches as far as I'm
>> concerned.
>
> Yep, please feel free to commit these, they look good to me as well.

Ok.  I've added a few test cases as well.

In Christ,
Steven Watanabe

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[Aleksey Gurtovoy]

On Tue, 14 Jul 2009 11:53:04 -0500, Steven Watanabe <watanabesj@...>  
wrote:

> AMDG
>
> Aleksey Gurtovoy wrote:
>> On Tue, 14 Jul 2009 02:19:19 -0500, David Abrahams <dave@...>  
>> wrote:
>>
>>> Steven, you can go ahead and apply these patches as far as I'm
>>> concerned.
>>
>> Yep, please feel free to commit these, they look good to me as well.
>
> Ok.  I've added a few test cases as well.

Excellent, thanks again!

--
Aleksey Gurtovoy
MetaCommunications Engineering

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