vector::resize() compilation error with msvc-10..12: data is not a member of boost::detail::aligned_storage...

[awulkiew]

Detected in Geometry R-tree tests. See https://www.boost.org/development/tests/develop/developer/geometry-index.html for msvc-10..12 x64 on x64, e.g.: https://www.boost.org/development/tests/develop/developer/output/teeks99-09-m-win2012R2-32on64-boost-bin-v2-libs-geometry-index-test-rtree-interprocess-rtree_interprocess_rstar_dyn-test-msvc-12-0-dbg-async-excpt-on-thrdp-wn32-thrd-mlt.html

For convenience, the error is:

D:\teeks99-09\run\boost_root\boost/container/detail/advanced_insert_int.hpp(132) : error C2039: 'data' : is not a member of 'boost::detail::aligned_storage::aligned_storage_imp<24,8>'
        D:\teeks99-09\run\boost_root\boost/container/detail/advanced_insert_int.hpp(129) : while compiling class template member function 'void boost::container::dtl::insert_value_initialized_n_proxy<boost::container::new_allocator<T>,T *>::copy_n_and_update(Allocator &,Iterator,unsigned int) const'
        with
        [
            T=child_contents
,            Allocator=boost::container::new_allocator<child_contents>
,            Iterator=child_contents *
        ]
        D:\teeks99-09\run\boost_root\boost/container/vector.hpp(2983) : see reference to function template instantiation 'void boost::container::dtl::insert_value_initialized_n_proxy<boost::container::new_allocator<T>,T *>::copy_n_and_update(Allocator &,Iterator,unsigned int) const' being compiled
        with
        [
            T=child_contents
,            Allocator=boost::container::new_allocator<child_contents>
,            Iterator=child_contents *
        ]

The vector::resize() is called in the R-tree here: https://github.com/boostorg/geometry/blob/develop/include/boost/geometry/index/detail/rtree/rstar/choose_next_node.hpp#L83 container_from_elements_type is defined here: https://github.com/boostorg/geometry/blob/develop/include/boost/geometry/index/detail/rtree/node/node_elements.hpp#L97 and is simply boost::container::vector<child_contents> Element child_contents is boost::tuple<size_t, double, double>.

I tired with type different than boost::tuple<...> but of the same size (tuple elements as members), the result is the same. However synthetic test, so creating a vector of elements of the same size and alignment and resizing it outside the R-tree code passes. Funnily enough (in the R-tree) creating a vector of desired size with ctor instead of creating wieh default ctor and resizing it works, so instead of this:

typename rtree::container_from_elements_type<children_type, child_contents>::type children_contents;
children_contents.resize(children_count);

this:

typename rtree::container_from_elements_type<children_type, child_contents_t>::type
    children_contents(children_count);

I'll try to prepare a limited/synthetic case for this issue but in the meanwhile maybe do you have an idea why this may be the case?

[awulkiew]

It seems that it doesn't have to be x64 mode, it also fails with msvc-12 in x86 mode e.g.: https://www.boost.org/development/tests/develop/developer/output/teeks99-09-m-win2012R2-32on64-boost-bin-v2-libs-geometry-index-test-rtree-interprocess-rtree_interprocess_rstar_dyn-test-msvc-12-0-dbg-async-excpt-on-thrdp-wn32-thrd-mlt.html surprisingly this test passes with msvc-10 and 11.

FYI, I modified the code by replacing resize() with ctor so these errors will probably disappear.

[igaztanaga]

No idea of what the problem might be. If you provide me a simplified test I could try to understand how MSVC 10-12 does not like the code

[awulkiew]

After heavy digging I was able to write a simple failing test. There are some specific conditions for the error to happen. I tried to simplify the code and destille the problem as much as I could. However the limit here is Container and Variant interface. I suspect it's possible to simplify it even more by checking the internals of both libraries. I hope the code below will at least make your day. ;)

#include <boost/container/vector.hpp>
#include <boost/variant.hpp>

// conditions:
// sizeof(foo) == sizeof(bar)
// same number of members
// memory model doesn't matter
// both variant must be created and vector::resize() called

struct foo
{
    void * a;
};

struct bar
{
//    float a; // error with x86
    double a; // error with x64
};

int main()
{
    boost::variant<foo> root; // without it ok

    boost::container::vector<bar> vec;
    children_contents.resize(0); // without it ok
}

[awulkiew]

Actually I found a fix for this. It seems that the compiler tries to instantiate boost::aligned_storage instead of boost::container::dtl::aligned_storage in this specific case. The former doesn't have data member variable, it has address() member function. So it can be fixed or rather worked around by prefixing aligned_storage with dtl:: namespace.

Side question, why are you using your own aligned_storage? AFAIU the "common" one is not a big dependency and it's used in container::node_handle anyway.

[igaztanaga]

Closing the issue after merging:

https://github.com/boostorg/container/commit/28e8d6da78a163d71390eb1b8b16724495013529