Re: [Boost-bugs] [Boost C++ Libraries] #6237: unordered_set behaves differently from 1.46 to 1.48

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #6237: unordered_set behaves differently from 1.46 to 1.48
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2011-12-08 08:58:47

#6237: unordered_set behaves differently from 1.46 to 1.48
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  Reporter:  Chris Meyer <cmeyer1969+boost@…>          |       Owner:  danieljames
      Type:  Bugs                                      |      Status:  new        
 Milestone:  To Be Determined                          |   Component:  unordered  
   Version:  Boost 1.48.0                              |    Severity:  Regression 
Resolution:                                            |    Keywords:             
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Comment (by anonymous):

 No, it's valid, you're using a custom `operator==` so for it to work you
 need to use a custom hash function. For this case,:

 {{{
 bool operator==(const cptr &c1, const cptr &c2) { return true; }
 // Since cptr is always equal just hash to the same value.
 std::size_t hash_value(const cptr& c1) { return 1; }
 }}}

 The hash function for your real code depends on what your equality
 operator does. This only worked before because there was a bug for hashing
 shared_ptr so they all went into the same bucket. This worked but was very
 inefficient.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/6237#comment:1>
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