intrusive_repro.cpp

#include <boost/intrusive/unordered_set.hpp>
#include <vector>

using B = boost::intrusive::unordered_set_base_hook<
    boost::intrusive::link_mode<boost::intrusive::normal_link>>;

struct element : B
{
    element(int i) : value_{i}
    {
    }
    friend bool
    operator==(element const& lhs, element const& rhs)
    {
        return lhs.value_ == rhs.value_;
    }
    friend std::size_t
    hash_value(element const& v)
    {
        return std::size_t(v.value_);
    }
    int value_;
};

template <bool CacheBegin>
void
testIt()
{
    using T = typename boost::intrusive::make_unordered_set<element,
        boost::intrusive::constant_time_size<true>, void, void,
        boost::intrusive::cache_begin<CacheBegin>>::type;
    using bucket_type = T::bucket_type;
    using bucket_traits = T::bucket_traits;

    std::vector<bucket_type> buckets;
    buckets.resize(3);
    T c(bucket_traits(&buckets[0], buckets.size()));

    // If we add elements before rehashing, we're OK
    // Hoever, if the container is empty, we hit the assert.
    if (0)
    {
        std::vector<element> v;
        v.emplace_back(0);
        c.insert(v.begin(), v.end());
    }

    {
        std::vector<bucket_type> tmp;
        std::swap(tmp, buckets);
        buckets.resize(7);
        c.rehash(bucket_traits(&buckets[0], buckets.size()));
    }
}

int
main()
{
    testIt<false>();
    testIt<true>();
    // When the "CacheBegin" parameter is set to true, we hit an assert:
    // clang-format off
    // main: /home/swd/projs/packages/vcpkg/installed/x64-linux/include/boost/intrusive/hashtable.hpp:1264: void boost::intrusive::bucket_hash_equal_t<ValueTraits, VoidOrKeyOfValue, VoidOrKeyHash, VoidOrKeyEqual, BucketTraits, true>::priv_insertion_update_cache(std::size_t) [with ValueTraits = boost::intrusive::bhtraits<element, boost::intrusive::slist_node_traits<void*>, boost::intrusive::normal_link, boost::intrusive::dft_tag, 4>; VoidOrKeyOfValue = void; VoidOrKeyHash = void; VoidOrKeyEqual = void; BucketTraits = boost::intrusive::bucket_traits_impl<boost::intrusive::get_slist_impl<boost::intrusive::slist_node_traits<void*> >::type>; std::size_t = long unsigned int]: Assertion `insertion_bucket < this->bucket_hash_type::priv_bucket_count()' failed.
    // clang-format on

    return 0;
}