Errors with boost(1.70.0) in using ptr_vector

[kkumar45]

I am moving from Boost 1.65.1 to 1.70.0. My project has the usage of "ptr_vector" in function parameter. The build is failing in 1.70.0. I have written a program that demonstrates the problem in using "ptr_vector" in function parameter.

Command used for compiling: g++ -std=c++14 ptr_vector_test.cpp -Iboost_1_70_0

Test Program:

#include <boost/ptr_container/ptr_vector.hpp>
namespace A
{
    template<class T>
    class Foo
    {
        public:
        static void test(boost::ptr_vector<Foo<T>>& t){
            return;
        }
    };
    template<class T>
    using test = boost::ptr_vector<Foo<T>>;
}

int main()
{

    A::test<double> ptr;
    return 0;
}

Error (On Linux : gcc 6.3.0)

ptr_vector_test.cpp: In instantiation of ‘class A::Foo<double>’:
boost_1_70_0/boost/ptr_container/nullable.hpp:55:13:   recursively required by substitution of ‘template<class T> boost::type_traits::yes_type boost::ptr_container_detail::is_nullable(const boost::nullable<T>*) [with T = <missing>]’
boost_1_70_0/boost/ptr_container/nullable.hpp:55:13:   required from ‘const bool boost::is_nullable<A::Foo<double> >::value’
boost_1_70_0/boost/mpl/if.hpp:63:11:   required from ‘struct boost::mpl::if_<boost::is_nullable<A::Foo<double> >, A::Foo<double>, boost::mpl::identity<A::Foo<double> > >’
boost_1_70_0/boost/mpl/eval_if.hpp:37:41:   required from ‘struct boost::mpl::eval_if<boost::is_nullable<A::Foo<double> >, A::Foo<double>, boost::mpl::identity<A::Foo<double> > >’
boost_1_70_0/boost/ptr_container/nullable.hpp:69:13:   required from ‘struct boost::remove_nullable<A::Foo<double> >’
boost_1_70_0/boost/ptr_container/nullable.hpp:80:55:   required from ‘struct boost::ptr_container_detail::void_ptr<A::Foo<double> >’
ptr_vector_test.cpp:18:43:   required by substitution of ‘template<class T> using test = boost::ptr_vector<A::Foo<T> > [with T = double]’
ptr_vector_test.cpp:26:19:   required from here
ptr_vector_test.cpp:11:21: error: no type named ‘type’ in ‘struct boost::ptr_container_detail::void_ptr<A::Foo<double> >’
         static void test(boost::ptr_vector<Foo<T>>& t){

Clang command:

clang++ -std=c++14 ptr_vector_test.cpp -Iboost_1_70_0

Error( On Clang):

In file included from ptr_vector_test.cpp:1:
boost_1_70_0/boost/ptr_container/ptr_vector.hpp:35:91: error: no type named 'type' in 'boost::ptr_container_detail::void_ptr<A::Foo<double> >'
        class Allocator      = std::allocator<typename ptr_container_detail::void_ptr<T>::type>
                                              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
ptr_vector_test.cpp:11:33: note: in instantiation of default argument for 'ptr_vector<A::Foo<double>, boost::heap_clone_allocator>' required here
        static void test(boost::ptr_vector<Foo<T>>& t){
                                ^~~~~~~~~~~~~~~~~~
boost_1_70_0/boost/ptr_container/nullable.hpp:55:57: note: in instantiation of template class 'A::Foo<double>' requested here
            BOOST_STATIC_CONSTANT(bool, value = sizeof( ptr_container_detail::is_nullable( var ) ) 
                                                        ^
boost_1_70_0/boost/mpl/if.hpp:63:68: note: in instantiation of template class 'boost::is_nullable<A::Foo<double> >' requested here
          BOOST_MPL_AUX_STATIC_CAST(bool, BOOST_MPL_AUX_VALUE_WKND(T1)::value)
                                                                   ^
boost_1_70_0/boost/mpl/eval_if.hpp:37:22: note: in instantiation of template class 'boost::mpl::if_<boost::is_nullable<A::Foo<double> >, A::Foo<double>, boost::mpl::identity<A::Foo<double> > >' requested here
    typedef typename if_<C,F1,F2>::type f_;
                     ^
boost_1_70_0/boost/ptr_container/nullable.hpp:66:45: note: in instantiation of template class 'boost::mpl::eval_if<boost::is_nullable<A::Foo<double> >, A::Foo<double>, boost::mpl::identity<A::Foo<double> > >' requested here
        typedef BOOST_DEDUCED_TYPENAME mpl::eval_if< is_nullable<T>,
                                            ^
boost_1_70_0/boost/ptr_container/nullable.hpp:79:61: note: in instantiation of template class 'boost::remove_nullable<A::Foo<double> >' requested here
                              BOOST_DEDUCED_TYPENAME boost::remove_nullable<T>::type >::value,
                                                            ^
boost_1_70_0/boost/ptr_container/ptr_vector.hpp:35:78: note: in instantiation of template class 'boost::ptr_container_detail::void_ptr<A::Foo<double> >' requested here
        class Allocator      = std::allocator<typename ptr_container_detail::void_ptr<T>::type>
                                                                             ^
ptr_vector_test.cpp:18:5: note: in instantiation of default argument for 'ptr_vector<A::Foo<double>, boost::heap_clone_allocator>' required here
    using test = boost::ptr_vector<Foo<T>>;
    ^~~~~
ptr_vector_test.cpp:26:8: note: in instantiation of template type alias 'test' requested here
    A::test<double> ptr;
       ^
1 error generated.

[kkumar45]

Can anyone reproduce it?

[mclow]

Yep, I'm seeing it.

It appears to me that the basic problem is that boost::ptr_vector<Foo<T>> is not a complete type when you are trying to use it (you're still defining Foo).

[mclow]

Verified that it fails with Boost 1.66.0 as well.

[mclow]

This commit appears to be the behavior change: https://github.com/boostorg/ptr_container/commit/d1a588b25d2d7d510dadcf5d839c77b0998c58ab

[pdimov]

See PR #24.