IV95454: STD::REL_OPS OPERATOR RESOLUTION CONFLICT FOR REVERSE_ITERATOR TYPE

XL C/C++ for AIX, V13.1.3.4 Fix Pack (April 2017)
XL C/C++ Runtime for AIX, V13.1.3.2 Fix Pack (April 2017)
XL C/C++ Runtime for AIX, V13.1.3.3 Fix Pack (June 2017)
XL C/C++ for AIX, V13.1.3.5 Fix Pack (July 2018)
XL C/C++ for AIX, V13.1.3.6 Fix Pack (May 2019)

APAR status

• Closed as program error.

Error description

• A conflict exists during template resolution between template
  operators for the reverse_iterator type.
  
  The reverse_iterator parameter operators defined in <xutility>
  may conflict with the more generic operators in <utility> when
  the std::rel_ops namespace is used:
  
  
  <xutility>
     449  template<class _RIL, class _RIR> inline
     450        bool operator!=(const reverse_iterator<_RIL>&_X,
     451                        const reverse_iterator<_RIR>&_Y)
     452          {return (!(_X == _Y)); }
  
  <utility>
     113  template<class _Ty> inline
     114          bool operator!=(const _Ty& _X, const _Ty& _Y)
     115          {return (!(_X == _Y)); }
  
  
     === TEST CASE ===
  
  #include <utility>
  #include <xutility>
  #include <deque>
  
  class MyElement { int a; };
  
  class MyList
  {
    public:
       std::deque<MyElement>::reverse_iterator end();
  };
  
  using namespace std::rel_ops;
  
  class MyClass
  {
   public:
    MyList list;
    inline bool mytest();
    std::deque<MyElement>::reverse_iterator position;
  };
  
  inline bool MyClass::mytest()
  {
          return(position != list.end());
          //return( std::operator!=(position,list.end()));
  }
  
  bool test()
  {
   MyClass a;
   return a.mytest();
  }
  
  
  
  > xlC -c apar.cpp
  "./apar.cpp", line 25.25: CCN5219 (S) The call to "operator!="
  has no best match.
  
  "./apar.cpp", line 25.16: CCN6228 (I) Argument number 1 is an
  lvalue of type "std::deque<MyElement,std::allocator<MyElement>
  >::reverse_iterator".
  "./apar.cpp", line 25.36: CCN6229 (I) Argument number 2 is an
  rvalue of type
  "std::reverse_iterator<std::deque<MyElement,std::allocator<MyEle
  ment> >::iterator>".
  
  "/usr/include/xutility", line 450.14: CCN6202 (I) No candidate
  is better than "std::operator!=
  <std::deque<MyElement,std::allocator<MyElement>
  >::iterator,std::deque<MyElement,std::allocator<MyElement>
  >::iterator>(const
  reverse_iterator<std::deque<MyElement,std::allocator<MyElement>
  >::iterator> &, const
  reverse_iterator<std::deque<MyElement,std::allocator<MyElement>
  >::iterator> &)".
  "./apar.cpp", line 25.16: CCN6231 (I) The conversion from
  argument number 1 to "const
  std::reverse_iterator<std::deque<MyElement,std::allocator<MyElem
  ent> >::iterator> &" uses "the identity conversion".
  "./apar.cpp", line 25.36: CCN6231 (I) The conversion from
  argument number 2 to "const
  std::reverse_iterator<std::deque<MyElement,std::allocator<MyElem
  ent> >::iterator> &" uses "the identity conversion".
  
  "/usr/include/utility", line 114.14: CCN6202 (I) No candidate is
  better than "std::rel_ops::operator!=
  <std::reverse_iterator<std::deque<MyElement,std::allocator<MyEle
  ment> >::iterator> >(const
  reverse_iterator<std::deque<MyElement,std::allocator<MyElement>
  >::iterator> &, const
  reverse_iterator<std::deque<MyElement,std::allocator<MyElement>
  >::iterator> &)".
  "./apar.cpp", line 25.16: CCN6231 (I) The conversion from
  argument number 1 to "const
  std::reverse_iterator<std::deque<MyElement,std::allocator<MyElem
  ent> >::iterator> &" uses "the identity conversion".
  "./apar.cpp", line 25.36: CCN6231 (I) The conversion from
  argument number 2 to "const
  std::reverse_iterator<std::deque<MyElement,std::allocator<MyElem
  ent> >::iterator> &" uses "the identity conversion".
  
  CCN0793(I) Compilation failed for file ./apar.cpp.  Object file
  not created.
  >
  

Local fix

• Call the required operator explicitly, as per the example above:
  
     return( std::operator!=(position,list.end()));
  

Problem summary

• PROBLEM DESCRIPTION:
  The std::rel_ops operators require the same type for both
  parameters.  Specializations of the same reverse_allocator type
  for both parameters are missing in the STL for these operators
  and therefore, applications fail to compile if they are used.
  
  USERS AFFECTED:
  Users who use std::rel_ops operators with the reverse_allocator
  type.
  

Problem conclusion

• The problem has been fixed.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

  PI79959

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  XL C/C++ RUNTIM

• Fixed component ID

  5725C7201

Applicable component levels