IZ33823: Error being incorrectly generated by the xlC compiler

January 2009 PTF for XL C/C++ Enterprise Edition for AIX, V9.0
April 2009 PTF for XL C/C++ Enterprise Edition for AIX, V9.0
July 2009 PTF for XL C/C++ Enterprise Edition for AIX, V9.0
November 2010 PTF for XL C/C++ Enterprise Edition for AIX, V9.0
March 2011 PTF for XL C/C++ Enterprise Edition for AIX, V9.0
July 2011 PTF for XL C/C++ Enterprise Edition for AIX, V9.0
December 2011 PTF for XL C/C++ Enterprise Edition for AIX, V9.0
March 2012 PTF for XL C/C++ Enterprise Edition for AIX, V9.0
January 2010 PTF for XL C/C++ Enterprise Edition for AIX, V9.0
May 2010 PTF for XL C/C++ Enterprise Edition for AIX, V9.0
August 2010 PTF for XL C/C++ Enterprise Edition for AIX, V9.0

APAR status

• Closed as program error.

Error description

• Problem:
  A friend declaration inside of a class inside of a namespace
  inside
  of an extern "C" block is incorrectly generating an error.
  
  =====Start of a.C======
  extern "C" {
    namespace N {
    struct A {
      friend void foo();
    };
    }
  }
  ==========End of a.C==============
  
  $xlC -c a.C
  "a.C", line 4.19: 1540-0434 (S) The friend function must also be
  declared in the enclosing block scope.
  

Local fix

• You can also use a work around to solve the problem.  The
  original code had extern "C" around everything (i.e. the
  namespace and class definition).  This is overkill and can be
  confusing since the member functions have to follow the C++
  linkage.  If it is feasible you can look at changing the source
  code to something more accurate.  See the following example.
  This gives you an alternate to waiting for an interim compiler
  fix.  The work around is still valid C++ code and should be
  compiled by other compilers too.
  
  -- a-fix.C
  namespace N {
    extern "C" {
      void foo();
    }
    struct A {
      friend void foo();
    };
  }
  -- a-fix.C --
  This work around is more typical C++ code.  You should have
  better luck porting it from compiler to compiler.
  

Problem summary

• Users who want to have a friend declaration inside a
  class/struct inside of a namespace inside of an extern "C"
  block. An incorrect error was generated.
  
  The original intent of the error is to catch friend declaration
  inside a local class (without prior declaration).
  We incorrectly applied the same check on a namespace inside of
  an extern "C" block.
  

Problem conclusion

• Additional if statements are in place to distinguish a local
  class from a namespace inside of an extern "C" block before the
  check.
  

Temporary fix

Comments

APAR Information

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

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

  IZ42383 LI74341 LI74785

Fix information

• Fixed component name

  XLC C++ AIX

• Fixed component ID

  5724S7100

Applicable component levels