Build error with Boost 1.58.0

[eschnett]

HPX does not build with Boost 1.58.0 on OS X. It fails with the error message

/Users/eschnett/software/boost-1.58.0/include/boost/serialization/vector.hpp:216:18: error: comparison of integers of different signs: 'int' and 'base_type' (aka 'unsigned long') [-Werror,-Wsign-compare]
    for(i = 0; i < count; ++i){
               ~ ^ ~~~~~

which is caused by this Boost routine:

template<class Archive, class Allocator>
inline void load(
    Archive & ar,
    std::vector<bool, Allocator> &t,
    const unsigned int /* file_version */
){
    // retrieve number of elements
    collection_size_type count;
    ar >> BOOST_SERIALIZATION_NVP(count);
    t.resize(count);
    int i;
    for(i = 0; i < count; ++i){
        bool b;
        ar >> boost::serialization::make_nvp("item", b);
        t[i] = b;
    }
}

which compares int i with unsigned long count in the for loop. One wonders why the author uses int to iterate over a container in this day and age, in particular since the container's size type is readily available. I recommend switching to Cereal for serialization.

Can you disable -Werror for release builds of HPX? I agree this is very useful during development, but for a release this has too many false positives.

[sithhell]

HPX does not build with Boost 1.58.0 on OS X. It fails with the error message

/Users/eschnett/software/boost-1.58.0/include/boost/serialization/vector.hpp:216:18:
error: comparison of integers of different signs: 'int' and 'base_type'
(aka 'unsigned long') [-Werror,-Wsign-compare]
for(i = 0; i < count; ++i){
~ ^ ~~~~~

which is caused by this Boost routine:

template<class Archive, class Allocator>
inline void load(
Archive & ar,
std::vector<bool, Allocator> &t,
const unsigned int /* file_version */
){
// retrieve number of elements
collection_size_type count;
ar >> BOOST_SERIALIZATION_NVP(count);
t.resize(count);
int i;
for(i = 0; i < count; ++i){
bool b;
ar >> boost::serialization::make_nvp("item", b);
t[i] = b;
}
}

which compares int i with unsigned long count in the for loop. One
wonders why the author uses int to iterate over a container in this day and
age, in particular since the container's size type is readily available. I
recommend switching to Cereal for serialization.

Thanks for the report. This should be fixed on master as we removed
boost.serialization entirely.

Can you disable -Werror for release builds of HPX? I agree this is very
useful during development, but for a release this has too many false
positives.

Sounds like a good strategy. Eventually we want to make hpx itself
completely warning free for the next release. Disabling -Werror for
releases is a good idea in any case.

[hkaiser]

Our released versions were released before Boost 1.58 came out, so naturally we can't really support it. It will be supported with the next released version of HPX, though.