compile error when dereferencing a strided_iterator

[michael-brade]

It is not possible to compile a program that dereferences a strided_iterator:

boost::compute::int_ data[] = { 1, 2, 3, 4, 5, 6, 7, 8 };
auto it = boost::compute::make_strided_iterator(data, 3);
BOOST_CHECK_EQUAL(*it, 1);

That results in:

test_strided_iterator.cpp:22:
/compute/include/boost/compute/iterator/strided_iterator.hpp: In instantiation of ‘boost::compute::strided_iterator<Iterator>::reference boost::compute::strided_iterator<Iterator>::dereference() const [with Iterator = int*; boost::compute::strided_iterator<Iterator>::reference = int&]’:
/usr/include/boost/iterator/iterator_facade.hpp:550:31:   required from ‘static typename Facade::reference boost::iterators::iterator_core_access::dereference(const Facade&) [with Facade = boost::compute::strided_iterator<int*>; typename Facade::reference = int&]’
/usr/include/boost/iterator/iterator_facade.hpp:656:53:   required from ‘boost::iterators::detail::iterator_facade_base<Derived, Value, CategoryOrTraversal, Reference, Difference, false, false>::reference boost::iterators::detail::iterator_facade_base<Derived, Value, CategoryOrTraversal, Reference, Difference, false, false>::operator*() const [with Derived = boost::compute::strided_iterator<int*>; Value = int; CategoryOrTraversal = std::random_access_iterator_tag; Reference = int&; Difference = long int; boost::iterators::detail::iterator_facade_base<Derived, Value, CategoryOrTraversal, Reference, Difference, false, false>::reference = int&]’
/compute/test/test_strided_iterator.cpp:120:3:   required from here
/compute/include/boost/compute/iterator/strided_iterator.hpp:187:16: error: value-initialization of reference type ‘boost::compute::strided_iterator<int*>::reference’ {aka ‘int&’}
  187 |         return reference();
      |                ^~~~~~~~~~~
make[3]: *** [test/CMakeFiles/test_strided_iterator.dir/build.make:82: test/CMakeFiles/test_strided_iterator.dir/test_strided_iterator.cpp.o] Fehler 1
make[2]: *** [CMakeFiles/Makefile2:3532: test/CMakeFiles/test_strided_iterator.dir/all] Fehler 2

[michael-brade]

I will create a pull request in the next hour.