id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
6370	GCC sequence-point warning in unordered_map::iterator increment operator++	john@…	Daniel James	"The following code triggers GCC -Wsequence-point warning. It is unclear whether GCC has detected a bug in boost::unordered_map, or whether this is a false positive. 

{{{
#!cpp
#include <boost/unordered_map.hpp>
void f (){
    boost::unordered_map<int,int>::iterator i;
    ++i;
}
}}}

* The issue appears in boost 1_48 (latest).
* The issue does not appear in 1_47.
* The GCC version is 4.6.2 (latest).
* const_iterator does not trigger the issue.

The complete output is:

{{{
$ g++ -Wall -c issue.cpp 
In file included from /usr/include/boost/unordered/detail/equivalent.hpp:14:0,
                 from /usr/include/boost/unordered/unordered_map.hpp:18,
                 from /usr/include/boost/unordered_map.hpp:16,
                 from wtf.cpp:1:
/usr/include/boost/unordered/detail/table.hpp: In member function ‘boost::unordered::iterator_detail::iterator<NodePointer, Value>& boost::unordered::iterator_detail::iterator<NodePointer, Value>::operator++() [with NodePointer = boost::unordered::detail::ptr_node<std::pair<const int, int> >*, Value = std::pair<const int, int>, boost::unordered::iterator_detail::iterator<NodePointer, Value> = boost::unordered::iterator_detail::iterator<boost::unordered::detail::ptr_node<std::pair<const int, int> >*, std::pair<const int, int> >]’:
wtf.cpp:4:7:   instantiated from here
/usr/include/boost/unordered/detail/table.hpp:177:13: warning: operation on ‘((boost::unordered::iterator_detail::iterator<boost::unordered::detail::ptr_node<std::pair<const int, int> >*, std::pair<const int, int> >*)this)->boost::unordered::iterator_detail::iterator<boost::unordered::detail::ptr_node<std::pair<const int, int> >*, std::pair<const int, int> >::node_’ may be undefined [-Wsequence-point]
}}}
"	Bugs	closed	Boost 1.49.0	unordered	Boost 1.48.0	Problem	fixed