Re: [Boost-bugs] [Boost C++ Libraries] #3078: Assert failure caused by property_map with BGL bundled properties if compiled in Debug mode in VS2008 SP1

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #3078: Assert failure caused by property_map with BGL bundled properties if compiled in Debug mode in VS2008 SP1
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2009-05-25 21:33:25

#3078: Assert failure caused by property_map with BGL bundled properties if
compiled in Debug mode in VS2008 SP1
-------------------------------------------------------+--------------------
  Reporter:  Artyom Arabadji <sneg.vx_at_[hidden]>  |       Owner:  dgregor                  
      Type:  Bugs                                      |      Status:  closed                   
 Milestone:                                            |   Component:  property_map             
   Version:  Boost 1.38.0                              |    Severity:  Problem                  
Resolution:  invalid                                   |    Keywords:  bgl, property_map, vs2008
-------------------------------------------------------+--------------------
Changes (by jewillco):

  * status:  new => closed
  * resolution:  => invalid

Comment:

 There are two issues with your code.  The first one, that I think is
 causing your problem, is that you define a copy constructor that is empty
 and thus does not copy anything.  Therefore, your graph and edge list are
 not copied when your visitor is passed into depth_first_visit (which is
 done by copy), leading to the edge list being empty and thus the iterator
 in your property map being invalid.  The second issue is that you are
 storing the graph by copy in your visitor.  This wastes memory, and also
 (although this may not show up with your graph type) some graph types have
 vertex descriptors that are tied to a particular graph.  For example,
 using vertices from one graph to access edges or properties in a copy of
 that graph is invalid (and fails in subtle ways) for some instantiations
 of adjacency_list.  I actually noticed the copy constructor issue when I
 went to store the graph by reference and the compiler complained about the
 copy constructor.

 You should fix your problem in two ways:
 1. Change PathRecorder to store "const Graph&" rather than "const Graph".
 2. Remove the copy constructor and let the compiler-generated one (which
 works) be used, or add an explicit copy or reference of the edge data.
 Note that you may not want to do the default deep copy of that data; you
 might want to build the property map externally and only store it (and not
 its underlying data) in your visitor since property maps are copied
 shallowly.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/3078#comment:5>
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