[Boost-bugs] [Boost C++ Libraries] #1946: [type_traits] type_with_alignment fails on non-power-of-2 alignment

Subject: [Boost-bugs] [Boost C++ Libraries] #1946: [type_traits] type_with_alignment fails on non-power-of-2 alignment
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2008-05-24 15:22:59

#1946: [type_traits] type_with_alignment fails on non-power-of-2 alignment
-----------------------------------+----------------------------------------
 Reporter:  andysem_at_[hidden]        |       Owner:  johnmaddock
     Type:  Bugs                   |      Status:  new        
Milestone:  Boost 1.36.0           |   Component:  type_traits
  Version:  Boost 1.35.0           |    Severity:  Problem    
 Keywords:  type_traits alignment  |  
-----------------------------------+----------------------------------------
 The type_with_alignment template fails to compile if the alignment is not
 a power of 2. This is a possible situation at least with MSVC 9.0. The
 following class of a user-defined stream gets alignment of 12:

 class my_stream :
     public std::ostream
 {
 public:
     typedef boost::function0< void > function_type;
     function_type m_function;
 };

 I've attached a reduced code sample with more comments and the compiler
 error message.

 I suggest to add a fallback type_with_alignment type in case if the
 alignment is not a power of 2. This type should have the requested
 alignment. It may be achieved with the __declspec(align(n)) specifier.

-- 
Ticket URL: <http://svn.boost.org/trac/boost/ticket/1946>
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