id,summary,reporter,owner,description,type,status,milestone,component,version,severity,resolution,keywords,cc
6915,boost::fusion::result_of::invoke compilation errors,ulidtko@…,Joel de Guzman,"In Boost.Fusion 1.49.0, `boost::fusion::result_of::invoke` metafunction causes compilation errors in some cases of SFINAE usage.

See attachments for reproducing example.

Please note how the code works with trivial metafunction (`subst_failure_if_not_int`), and does not with `boost::fusion::result_of::invoke`, while being used in identical manner.

Also note that the following line:
{{{
  try_invoke<F, boost::fusion::vector<float>> (0);
}}}
 may compile or not depending on the `BOOST_RESULT_OF_USE_DECLTYPE` switch under GCC. Which is a fair clue of that this is probably boost's bug.


== Compiler error messages ==

=== MSVC 9 ===
{{{
d:\boost\1_49_0\boost\fusion\functional\invocation\invoke.hpp(199) : error C2039: 'type' : is not a member of 'boost::result_of<F>'
d:\boost\1_49_0\boost\fusion\functional\invocation\invoke.hpp(159) : see reference to class template instantiation 'boost::fusion::detail::invoke_impl<Function,Sequence>' being compiled
..\substitution_failure_test.cpp(60) : see reference to class template instantiation 'boost::fusion::result_of::invoke<Function,Sequence>' being compiled
        with
        [
            Function=F,
            Sequence=boost::fusion::vector<float>
        ]
}}}

=== GCC 4.5.3 ===
When compiling with `#define BOOST_RESULT_OF_USE_DECLTYPE 1`:
{{{
In file included from D:/boost/1_49_0/boost/preprocessor/iteration/detail/iter/forward1.hpp:52:0,
                 from D:/boost/1_49_0/boost/utility/result_of.hpp:95,
                 from D:/boost/1_49_0/boost/fusion/support/detail/segmented_fold_until_impl.hpp:13,
                 from D:/boost/1_49_0/boost/fusion/sequence/intrinsic/detail/segmented_begin_impl.hpp:15,
                 from D:/boost/1_49_0/boost/fusion/sequence/intrinsic/detail/segmented_begin.hpp:10,
                 from D:/boost/1_49_0/boost/fusion/sequence/intrinsic/begin.hpp:17,
                 from D:/boost/1_49_0/boost/fusion/container/vector/vector10.hpp:15,
                 from D:/boost/1_49_0/boost/fusion/container/vector.hpp:12,
                 from D:/boost/1_49_0/boost/fusion/container.hpp:10,
                 from substitution_failure_test.cpp:5:
D:/boost/1_49_0/boost/utility/detail/result_of_iterate.hpp: In instantiation of ‘boost::detail::cpp0x_result_of_impl<F(junk&)>’:
D:/boost/1_49_0/boost/utility/detail/result_of_iterate.hpp:52:1:   instantiated from ‘boost::result_of<F(junk&)>’
D:/boost/1_49_0/boost/fusion/functional/invocation/invoke.hpp:199:60:   instantiated from ‘boost::fusion::detail::invoke_impl<F, boost::fusion::vector<junk>, 1, false, true>’
D:/boost/1_49_0/boost/fusion/functional/invocation/invoke.hpp:159:30:   instantiated from ‘boost::fusion::result_of::invoke<F, boost::fusion::vector<junk> >’
substitution_failure_test.cpp:65:47:   instantiated from here
D:/boost/1_49_0/boost/utility/detail/result_of_iterate.hpp:64:5: error: no match for call to ‘(F) (junk&)’
substitution_failure_test.cpp:39:6: note: candidate is: int F::operator()(float)
}}}

Without:
{{{
In file included from D:/boost/1_49_0/boost/preprocessor/iteration/detail/iter/forward1.hpp:52:0,
                 from D:/boost/1_49_0/boost/fusion/functional/invocation/invoke.hpp:93,
                 from D:/boost/1_49_0/boost/fusion/functional/invocation.hpp:12,
                 from D:/boost/1_49_0/boost/fusion/functional.hpp:12,
                 from substitution_failure_test.cpp:7:
D:/boost/1_49_0/boost/fusion/functional/invocation/invoke.hpp: In instantiation of ‘boost::fusion::detail::invoke_impl<F, boost::fusion::vector<float>, 1, false, true>’:
D:/boost/1_49_0/boost/fusion/functional/invocation/invoke.hpp:159:30:   instantiated from ‘boost::fusion::result_of::invoke<F, boost::fusion::vector<float> >’
substitution_failure_test.cpp:62:48:   instantiated from here
D:/boost/1_49_0/boost/fusion/functional/invocation/invoke.hpp:199:60: error: no type named ‘type’ in ‘struct boost::result_of<F(float&)>’
D:/boost/1_49_0/boost/fusion/functional/invocation/invoke.hpp: In instantiation of ‘boost::fusion::detail::invoke_impl<F, boost::fusion::vector<junk>, 1, false, true>’:
D:/boost/1_49_0/boost/fusion/functional/invocation/invoke.hpp:159:30:   instantiated from ‘boost::fusion::result_of::invoke<F, boost::fusion::vector<junk> >’
substitution_failure_test.cpp:65:47:   instantiated from here
D:/boost/1_49_0/boost/fusion/functional/invocation/invoke.hpp:199:60: error: no type named ‘type’ in ‘struct boost::result_of<F(junk&)>’
}}}

,,PS: ''I ♥ search engines.'',,",Bugs,closed,To Be Determined,fusion,Boost 1.49.0,Problem,fixed,,