Re: [Boost-bugs] [Boost C++ Libraries] #5706: Gcc 4.6 warnings for Boost Graph

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #5706: Gcc 4.6 warnings for Boost Graph
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2013-12-17 16:24:36

#5706: Gcc 4.6 warnings for Boost Graph
--------------------------------------+------------------------------------
  Reporter:  ramon.casellas@…         |      Owner:  asutton
      Type:  Feature Requests         |     Status:  closed
 Milestone:  Boost 1.48.0             |  Component:  graph
   Version:  Boost Development Trunk  |   Severity:  Optimization
Resolution:  wontfix                  |   Keywords:  uninitialized warnings
--------------------------------------+------------------------------------

Comment (by Timmie Smith <timmie@…>):

 The warnings are still displayed using gcc 4.7.2 -O3 on Fedora.

 In boost/graph/detail/adj_list_edge_iterator.hpp
 boost::detail::adj_list_edge_iterator::operator!= is implemented as

 {{{
       inline bool operator!=(const self& x) const {
         return vCurr != x.vCurr
           || (vCurr != vEnd
               && edges BOOST_GRAPH_MEMBER first != x.edges
 BOOST_GRAPH_MEMBER first);
 }}}

 The unconditional access of this->edges.first and x.edges.first is
 incorrect in my opinion, as the edges data member in either instance may
 be uninitialized.

 Patching the operator to first check if the edges data members are
 initialized eliminates the warning and the evaluation should short circuit
 in the case that they aren't, eliminating the access of edges.first if
 edges isn't initialized.

 {{{
       inline bool operator!=(const self& x) const {
         return vCurr != x.vCurr
           || (vCurr != vEnd
               && edges && x.edges && edges BOOST_GRAPH_MEMBER first !=
 x.edges BOOST_GRAPH_MEMBER first);
 }}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/5706#comment:2>
Boost C++ Libraries <http://www.boost.org/>
Boost provides free peer-reviewed portable C++ source libraries.