[Boost-bugs] [Boost C++ Libraries] #7678: multiple definitions of bool boost::polygon::belongs(...) by multiple #include

Subject: [Boost-bugs] [Boost C++ Libraries] #7678: multiple definitions of bool boost::polygon::belongs(...) by multiple #include
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-11-10 12:28:48

#7678: multiple definitions of bool  boost::polygon::belongs(...) by multiple
#include
-------------------------------------------+--------------------------------
 Reporter:  Manfred <kuhnkies@…>           |       Owner:  ljsimons
     Type:  Bugs                           |      Status:  new     
Milestone:  To Be Determined               |   Component:  polygon 
  Version:  Boost 1.52.0                   |    Severity:  Problem 
 Keywords:  polygon, voronoi               |  
-------------------------------------------+--------------------------------
 Hello,

 my notice:

 I encountered a linker problem within the voronoi code of library
 boost::polygon when using MSVS 2008. There (and I guess on many other
 compilers) will be multiple definitions of function
  bool boost::polygon::belongs(...)
 as soon as there is direct or transitive
  #include <boost/polygon/voronoi_geometry_type.hpp>
 in more than one compile unit (.cpp file). This linker problem will not
 occur if only one .cpp file #includes this file (see single tutorial file
 libs/polygon/example/voronoi_visualizer.cpp and e.g. split this file into
 class related .h/.cpp files).

 my explanation:

 Seemingly compiling each compile unit like foo.cpp, bar.cpp, etc. produces
 a definition of
  bool boost::polygon::belongs(...)
 into its individual .obj-file, namely foo.obj, bar.obj, etc.. Later the
 linker can not resolve which of the multiple definitions of "belongs", the
 one in foo.obj or the one in bar.obj, to take when binding the executable.

 my suggestion:

 I could fix that problem in my local boost code by making "belongs" an
 inline function.
 {{{
  file    : boost/polygon/voronoi_geometry_type.hpp
  line 36 : bool belongs(           // taken from svn-trunk
  altered : inline bool belongs(    // my local modification
 }}}
 Inlining won't create any definition of "belongs" in .obj file(s) at all,
 hence no multiple definitions. There may be other, better solutions that I
 don't know of, of course.


 Best
   Manfred

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/7678>
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