[Boost-bugs] [Boost C++ Libraries] #6771: unordered_map comparing float in assertion statement causes large warning in gcc

Subject: [Boost-bugs] [Boost C++ Libraries] #6771: unordered_map comparing float in assertion statement causes large warning in gcc
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-04-06 12:05:43

#6771: unordered_map comparing float in assertion statement causes large warning
in gcc
---------------------------------------------------------+------------------
 Reporter:  Ryan Fogarty <ryan.fogarty.msece@…>          |       Owner:  danieljames
     Type:  Bugs                                         |      Status:  new        
Milestone:  To Be Determined                             |   Component:  unordered  
  Version:  Boost Release Branch                         |    Severity:  Problem    
 Keywords:                                               |  
---------------------------------------------------------+------------------
 In unordered/detail/table.hpp an assertion statement in function

 std::size_t min_buckets_for_size(std::size_t size) const

 compares a floating point which causes deeply nested warning statements in
 gcc with some compiler flags (possibly -Wall/-Wfloat-equal/-pedantic)

 {{{
             BOOST_ASSERT(this->mlf_ != 0);
 }}}

 Because of the nature of the template code the warning is very difficult
 to read and it is not obvious whether it is a problem in user's code or
 the library (from a quick glance). A simple alternative eliminates the
 issue:

 {{{
             BOOST_ASSERT(this->mlf_ > 0.0f || this->mlf_ < 0.0);
 }}}

 Bug has existed for quite a while. It is at least as old as 1.46, and I've
 confirmed that exists in 1.47 (line:138) - 1.49 (line:387) and is also on
 the trunk.

 As an example The warning in gcc 4.7.0 ends with:
 /usr/local/boost_1_49_0/include/boost/unordered/detail/table.hpp:387:13:
 warning: comparing floating point with == or != is unsafe [-Wfloat-equal]

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/6771>
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