On 11/09/2021 13:10, Joaquín M López Muñoz via Boost-users wrote:

Em 11 de set de 2021, à(s) 13:51, John Emmas via Boost-users <boost-users@lists.boost.org> escreveu:

compiles now trigger a new assert in 'boost/intrusive/list.hpp':-

  //Constant-time size is incompatible with auto-unlink hooks!
  BOOST_STATIC_ASSERT(!(constant_time_size &&
                       ((int)value_traits::link_mode == (int)auto_unlink)
                     ));

The comment above the assert says it all. Take a look at how constant_time_size<false> is used in the docs for auto-unlink hooks.

Thanks again Joaquin - AFAICT the only occurrences of 'constant_time_size' are within libboost itself. In fact for 'class list_impl' it seems to be defined as a constant:-

    static const bool constant_time_size = ConstantTimeSize;

However, I've realised that the problem I reported initially (today) does seem to be connected to DLL linkage somehow. For example, this code in a source file compiles okay:-

    #include <boost/intrusive/list.hpp>
    class Point : public boost::intrusive::list_base_hook<> {
    };

whereas 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?

John