iterator::reference is a reference type: 1
iterator_range::reference is a reference type: 1
first[0] returns a reference type: 0
range[0] returns a reference type: 1
first[0] == 0
Segmentation fault (core dumped)
Expected behavior: range[0] returns 0.
If Boost headers are copied to ./boost and the program is compiled with g++ -I. option, the compiler produces the following warning:
In file included from ./boost/range/iterator_range.hpp:13,
from test_counting_iterator_range_indexing.cpp:2:
./boost/range/iterator_range_core.hpp: In instantiation of ‘boost::iterator_range_detail::iterator_range_base<IteratorT, boost::iterators::random_access_traversal_tag>::reference boost::iterator_range_detail::iterator_range_base<IteratorT, boost::iterators::random_access_traversal_tag>::operator[](boost::iterator_range_detail::iterator_range_base<IteratorT, boost::iterators::random_access_traversal_tag>::difference_type) const [with IteratorT = boost::iterators::counting_iterator<int>; boost::iterator_range_detail::iterator_range_base<IteratorT, boost::iterators::random_access_traversal_tag>::reference = const int&; boost::iterator_range_detail::iterator_range_base<IteratorT, boost::iterators::random_access_traversal_tag>::difference_type = long int]’:
test_counting_iterator_range_indexing.cpp:23:43: required from here
./boost/range/iterator_range_core.hpp:391:32: warning: returning reference to temporary [-Wreturn-local-addr]
return this->m_Begin[at];
^
The reason for the segmentation fault is that iterator_range::operator[] returns a reference to a stack-allocated object returned by counting_iterator::operator[].
Example:
Output:
Expected behavior:
range[0]
returns0
.If Boost headers are copied to
./boost
and the program is compiled with g++-I.
option, the compiler produces the following warning:The reason for the segmentation fault is that
iterator_range::operator[]
returns a reference to a stack-allocated object returned bycounting_iterator::operator[]
.