Re: Problem understanding 'boost::intrusive::list_member_hook<>'

From: Ion Gaztañaga (igaztanaga_at_[hidden])
Date: 2021-09-13 06:43:33

On 12/09/2021 9:26, John Emmas via Boost-users wrote:
> On 11/09/2021 14:59, John Emmas wrote:
>>
>> this seemingly minor change:-
>>
>>     #include <boost/intrusive/list.hpp>
>>     class __declspec(dllexport) Point : public 
>> boost::intrusive::list_base_hook<> {
>> };
>>
>> will immediately invoke this compile-time assertion:- 
>> "BOOST_STATIC_ASSERT(( (int)hooktags::link_mode == (int)auto_unlink 
>> ));" - i.e. the message I reported earlier...
>>
>> So (presumably ?) 'boost::intrusive::list_base_hook<>' can't be used 
>> in a class that'll get exported from a DLL?
>>
> 
> Just wondering if anyone can reproduce this?  Today I've tried 3 x 
> different revisions of libboost:- 1.77, 1.74 and 1.71 - but they all 
> give me the same assertion message.  So maybe it's an intentional 
> limitation?
> 
> John

hi,

Sorry about being missing these days. When you declare something as 
declspec the compiler must instantiate the class including all base 
classes. A base hook has members that have only sense when some options 
are used so the instantiation fails. To sum up: yes, boost.intrusive is 
not prepared to be used in a DLL interface.

Best,

Ion