Re: [Boost-bugs] [Boost C++ Libraries] #2704: range lock algorithm fails with iterators

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #2704: range lock algorithm fails with iterators
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2009-01-31 17:11:05

#2704: range lock algorithm fails with iterators
---------------------------------------+------------------------------------
  Reporter:  jwakely.boost_at_[hidden]  |       Owner:  anthonyw
      Type:  Bugs                      |      Status:  new     
 Milestone:  Boost 1.38.0              |   Component:  thread  
   Version:  Boost 1.37.0              |    Severity:  Problem 
Resolution:                            |    Keywords:          
---------------------------------------+------------------------------------

Comment(by jwakely.boost_at_[hidden]):

 gah, I've just noticed that trac concatenated the lines in the original
 test case I posted, so that the problem line was commented out. It should
 be:

 // boost::lock(&v.front(), &v.front()+v.size());

 boost::lock(v.begin(), v.end());

 the second line is the problem.

 Ignore the first patch, it's full of copy&paste errors. The second one
 fixes the original test case above, but fails for an iterator type like:

 struct iterator : std::vector<boost::mutex>::iterator
 {

   template<typename T> iterator(T t) :
 std::vector<boost::mutex>::iterator(t) { }

   iterator() : std::vector<boost::mutex>::iterator() { }

   iterator& operator++();

   iterator operator++(int);

   bool lock(int);  // confuses has_member_lock

 };

 The lock member means substitution succeeds, but the "dummy" parameter
 fails to compile because the signature of &U::lock doesn't match.

 The third patch handles the case above by extending sfinae_type to only
 succeed for members with the right signature.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/2704#comment:1>
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