[Boost-bugs] [Boost C++ Libraries] #5436: C++0x patch for boost::unit

Subject: [Boost-bugs] [Boost C++ Libraries] #5436: C++0x patch for boost::unit
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2011-04-07 10:42:17

#5436: C++0x patch for boost::unit
------------------------------+---------------------------------------------
 Reporter:  chrisj            |       Owner:  matthiasschabel
     Type:  Patches           |      Status:  new            
Milestone:  To Be Determined  |   Component:  units          
  Version:  Boost 1.47.0      |    Severity:  Problem        
 Keywords:                    |  
------------------------------+---------------------------------------------
 The attached patch makes boost::unit work correctly in C++0x, by making
 the code NOT compile when a dimension ordinal is used more than once.

 At the moment this code is only needed in clang's c++0x mode, but it
 doesn't seem to break g++ c++03 or c++0x, so put it all the time.

 The technique currently used (friend functions being double declared)
 doesn't work any more in C++0x, as:

 C++03 says: When a function is defined in a friend function declaration in
 a
 class template, the function is defined at each instantiation of the class
 template. The function is defined even if it is never used.

 C++0x says: When a function is defined in a friend function declaration in
 a
 class template, the function is instantiated when the function is odr-
 used.

 The new technique makes functions with different return values, which
 still causes an error.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/5436>
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