circular_buffer erroneously invalidates reverse_iterator at pop_back in debug mode

[christian.stimming@…]

The circular_buffer container offers reverse iterators. Using one so that it points to the second-to-last element would in theory allow to pop_back() the last element without causing problems with that iterator. However, apparently pop_back() invalidates those reverse iterators even though they wouldn't cause problems, as if the debug_iterator_registry in boost/circular_buffer/debug.hpp is working correctly only for forward iterators but not for backward iterators.

Example code that works fine without debug mode, but will run into a failed assertion in debug mode:

#define BOOST_CB_ENABLE_DEBUG #include <boost/circular_buffer.hpp> #include <iostream> int main(int /*argc*/, char /*argv*/) {

typedef boost::circular_buffer<int> CircBuffer; CircBuffer testBuffer(2); testBuffer.push_back(4); testBuffer.push_back(8);

CircBuffer::const_reverse_iterator bufIter = testBuffer.rbegin(); std::cout << "element at rbegin=" << *bufIter << std::endl; prints "=8" correctly ++bufIter; std::cout << "element after ++=" << *bufIter << std::endl; prints "=4" correctly testBuffer.pop_back(); std::cout << "elem=" << *bufIter << std::endl; ERROR: Causes "Assertion `is_valid(m_buff)' failed."

}