[Boost-bugs] [Boost C++ Libraries] #1518: Warning from gcc in boost/intrusive/detail/utilities.hpp

Subject: [Boost-bugs] [Boost C++ Libraries] #1518: Warning from gcc in boost/intrusive/detail/utilities.hpp
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2007-12-10 13:14:19

#1518: Warning from gcc in boost/intrusive/detail/utilities.hpp
-----------------------------------------------+----------------------------
 Reporter:  Lars Hagström <lars_at_[hidden]>  |       Owner:  igaztanaga  
     Type:  Bugs                               |      Status:  new         
Milestone:  To Be Determined                   |   Component:  interprocess
  Version:  Boost 1.34.1                       |    Severity:  Cosmetic    
 Keywords:                                     |  
-----------------------------------------------+----------------------------
 When compiling with -Wall and -O2 or -O3 I get the following warning:

 {{{
 intrusive/detail/utilities.hpp: In function 'float
 boost::intrusive::detail::fast_log2(float)':
 intrusive/detail/utilities.hpp:501: warning: dereferencing type-punned
 pointer will break strict-aliasing rules
 }}}

 This is with boost intrusive and interprocess from revision 41303.

 Changing the first line of fast_log2 to

 {{{
 boost::uint32_t * const exp_ptr =
   static_cast <boost::uint32_t * const>
    (static_cast<void * const >(&val));
 }}}

 Makes this warning go away. Although I'm not so sure about the beauty and
 efficiency of casting that way...

-- 
Ticket URL: <http://svn.boost.org/trac/boost/ticket/1518>
Boost C++ Libraries <http://www.boost.org/>
Boost provides free peer-reviewed portable C++ source libraries.