Re: [Boost-users] [fusion] Compile Error using BOOST_FUSION_DEFINE_STRUCT_INLINE with VC10 and GCC 4.2.1

Subject: Re: [Boost-users] [fusion] Compile Error using BOOST_FUSION_DEFINE_STRUCT_INLINE with VC10 and GCC 4.2.1
From: Oswin Krause (Oswin.Krause_at_[hidden])
Date: 2012-10-25 02:48:35

Done.

Do you know when you might get around to fix this issue? Currently this 
is a show stopper for my project.

Thanks for your support!

Regards,
Oswin

On 2012-10-25 00:25, Nathan Ridge wrote:
>> > If anyone can suggest a workaround for these compiler bugs, I am
>> > happy to
>> > implement them.
>> I have tried to understand what the macro generates and maybe we can
>> fix it by using fusion/mpl instead of partial template 
>> specialization. I
>> don't fully understand the macro, but maybe i am not too far off, so
>> that my solution might still work.
>>
>> the need for partial template spcialization arised because basically
>> the type/member list (A1, a1)(A2,a2)... is translated into
>>
>> typedef A1 t1_type;
>> typedef A2 t2_type;
>> ...
>> t1_type& t1;//linked to a1
>> t2_type& t2;//linked to a2
>> ...
>>
>> or something very similar to it.
>>
>> thus you need to specialize deref to do something roughly like( i
>> simplyfy here because i am too lazy to look up the original 
>> solution):
>>
>> template<int>
>> struct deref{};
>> template<>
>> struct deref<1>{
>> typedef t1_type& type;
>> type call(Sequence& seq){
>> return seq.t1;
>> }
>> };
>> ...
>>
>> now think about the following:
>> typedef boost::fusion::vector<A1&,A2&,...AN&> t_seq;
>> t_seq t;//tied to a1...an
>> template<int N>
>> struct deref{
>> typedef result_of::at_c<t_types,N> type;
>> type call(Sequence& seq){
>> return at_c<N>(seq.t);
>> }
>> };
>>
>> could this work? Of course this is detrimental to the compil times
>> since fusion::vector needs to be itnroduced and instantiated. 
>> However
>> this might just be the solution used for GCC<4.5 and MSVC, in this 
>> cas
>> "slow" is better than "compiler gives up".
>
> Nice idea! I think that would work.
>
> Could you please file a Trac ticket for this with your example code?
> I will post a patch there once I've implemented the workaround.
>
> Regards,
> Nate
>
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