IV68200: TEMPLATE CLASS CONST MEMBER ACCESS ERROR

XL C/C++ for AIX Fix Pack 3 (April 2015 PTF) for 13.1
XL C/C++ for AIX Fix Pack 4 (July 2015 PTF) for 13.1
XL C/C++ for AIX Fix Pack 5 (November 2015 PTF) for 13.1
XL C/C++ for AIX Fix Pack 6 (February 2016 PTF) for 13.1
XL C/C++ for AIX Fix Pack 7 (May 2016 PTF) for 13.1
XL C/C++ for AIX Fix Pack 8 (August 2016 PTF) for 13.1
XL C/C++ for AIX Fix Pack 9 (June 2017 PTF) for 13.1
XL C/C++ for AIX Fix Pack 10 (February 2018 PTF) for 13.1
XL C/C++ for AIX Fix Pack 11 (November 2018 PTF) for 13.1

APAR status

• Closed as program error.

Error description

• Incorrect template function matching behaviour is seen when an
  argument accesses a const member of a class.  In some cases, an
  incorrect function could be called, or an internal compiler
  error may be seen.
  
  
  The root issue is due to the const-status of the access,
  following the C++03 standard.  When a static const member
  is being accessed by a non-static object in the form
  'objname.memname', the const-status of the access becomes
  non-const.  This occurs because the C++ const property is
  shallow, so the access inherits the const-status of 'objname'.
  An error message will be output.
  
  However, an access of the form 'objname::memname' accessing the
  same static const member will have type static const.
  
  
  This behaviour was not fully defined in C++03, but was
  clairified in C++11, which allows both accesses to be const.
  In C++11, public static const member being accessed using :: or
  . has the same behavior, whereas in C++03, accessing a value
  using :: uses the const-status of the static member, but
  accessing  using . will be affected by the object's const-status
  due to the shallow property.
  
  This release follows the C++03 behaviour.
  
  
  
  
     === TEST CASE ===
  
  extern "C" int printf(const char *, ...);
  template <int N> struct Q;
  
  template <typename T>
  void foo(T *, Q<(*T::bp).value> * = 0) { printf("BAD\n"); }
  
  void foo(void *) { printf("GOOD\n"); }
  
  struct B { static const int value = 5; };
  struct A { static B *bp; };
  
  int main(void) {
     A *ap = 0;
     foo(ap);
  }
  
  
  $ xlC test.cpp
  $ ./a.out
  BAD
  $
  

Local fix

Problem summary

• See above.
  

Problem conclusion

• The behaviour has been corrected to match C++03 behaviour.
  

Temporary fix

Comments

APAR Information

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

  IV68198

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

Fix information

• Fixed component name

  XL C/C++ FOR AI

• Fixed component ID

  5725C7200

Applicable component levels

• RD10 PSY

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