Re: [Boost-users] [MultiArray, Intrusive] Instantiating a multi_array of intrusive lists as a class member

On Fri, Dec 14, 2012 at 5:02 AM, Jiri Vyskocil wrote:

On Sun, 2012-12-09 at 22:40 -0800, Jeffrey Lee Hellrung, Jr. wrote:

- See if a std::vector< boost::intrusive::list > works.

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This construction compiles and works with gcc 4.7.2 in C++11 mode only. With wersion 4.7.2 in default mode and 4.6 in any mode, compilation fails with a similar error.

- See if a boost::multi_array< boost::container::vector > works.

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This compiles and works fine in both 4.6 and 4.7, even in non-C++11 mode

If the above nesting of data structures gives similar errors as the original combination (something about unavailability of a copy constructor and/or stuff involving boost::rv<>), then that would seem to confirm it's a Boost.Move + Boost.MultiArray incompatibility. At that point, the best options are either to patch Boost.MultiArray to be Boost.Move-aware (not sure how much work that would be...) or try gcc 4.7.x, where maybe Boost.Move would no longer have adverse effects (if rvalue references are enabled by default; I don't know actually if that's the case).

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GCC 4.7.2 won't compile the MultiArray of intrusive lists even in C++11 mode. It spews the same error as gcc 4.6 in C++0x mode:

/usr/include/boost/intrusive/list.hpp:1488:4: error: ‘boost::intrusive::list::list(const boost::intrusive::list&) [with T = Particle, O1 = boost::intrusive::none, O2 = boost::intrusive::none, O3 = boost::intrusive::none, boost::intrusive::list = boost::intrusive::list<Particle>]’ is private

It would be nice to have this working at least in the newer gcc, but I have no idea what to look for...

Ah, evidently boost::multiarray expects its value_type to be copy-constructible (at least), which Boost.Intrusive data structures are not [1]: "Boost.Intrusive containers are non-copyable and non-assignable." Also explains the failure of std::vector< boost::intrusive::list >, too, in C++03 mode. In C++11 mode, I guess std::vector (and similar) are able to fall back to using the move constructors and assignment operators of the Boost.Intrusive data structures. - Jeff [1] http://www.boost.org/doc/libs/1_52_0/doc/html/intrusive/intrusive_vs_nontrus...