[Boost-bugs] [Boost C++ Libraries] #7358: typedef T in Comparison class clashes with template argument T in d_ary_heap

Subject: [Boost-bugs] [Boost C++ Libraries] #7358: typedef T in Comparison class clashes with template argument T in d_ary_heap
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-09-10 14:54:56

#7358: typedef T in Comparison class clashes with template argument T in
d_ary_heap
-------------------------------------------------+--------------------------
 Reporter:  Alex Hagen-Zanker <ahh34@…>          |       Owner:  timblechmann
     Type:  Bugs                                 |      Status:  new         
Milestone:  To Be Determined                     |   Component:  heap        
  Version:  Boost 1.52.0                         |    Severity:  Problem     
 Keywords:  indirect compare                     |  
-------------------------------------------------+--------------------------
 The d_ary_heap does not compile (in VS2010) when the Comparison class
 contains a typedef T. The typedef takes prevalence over the template
 parameter T when the heap is derived from the Comparison class.

 I.e. the following pattern occurs:

 template<class T, class Cmp> struct heap_base : Cmp
 {
     typedef T value_type; // value_type = Cmp::T
 }


 See below for a complete failing example.

 This is a problem when Boost.Heap is used in combination with
 boost/pending/indirect_cmp.hpp.


 #include <boost/heap/d_ary_heap.hpp>

 struct less
 {
   typedef int T;
   bool operator()(const int& a, const int& b) const
   {
     return a < b;
   }
 };

 int main()
 {
   boost::heap::d_ary_heap<int, boost::heap::compare<less>,
 boost::heap::arity<4> > my_heap;
   return 0;
 }

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/7358>
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