LI77626: INVALID INCOMPLETE CLASS ERROR

XL C/C++ for Linux Fix Pack 8 (October 2015 Update) for 12.1
XL C/C++ for Linux Fix Pack 4 (October 2013 Update) for 12.1
XL C/C++ for Linux Fix Pack 5 (December 2013 Update) for 12.1
XL C/C++ for Linux Fix Pack 6 (February 2014 Update) for 12.1
XL C/C++ for Linux Fix Pack 7 (May 2014 Update) for 12.1

APAR status

• Closed as program error.

Error description

• Consider the following testcase:
  
  $cat test.cpp
  #include <iostream>
  
  class T
  {
  public:
      class D
      {
      public:
          const static int size = 0;
      };
  
      template<typename minus_1, bool flag>
      class N
      {
      public:
          const static int size = minus_1::size + 1;
      };
  };
  
  int main()
  {
      typedef T::N<T::N<T::D,0>, 0> MyExample;
  
      std::cout << "MyExample::size = " << MyExample::size <<
  "\n";
  
      return 0;
  }
  
  The compiler incorrectly issues error message:
  
  "test.cpp", line 16.33: 1540-0062 (S) The incomplete class
  "N<T::D,0>" must not be used as a qualifier.
  

Local fix

• Define the static member outside as in the example below:
  
  $cat test.cpp
  struct T
  {
      struct D
      {
          const static int size = 0;
      };
  
      template<typename minus_1, bool flag> struct N
      {
          const static int size;
      };
  };
  
  template <typename X, bool Y>
  const int T::N<X,Y>::size = X::size+1;
  
  int main()
  {
      typedef T::N<T::N< T::D, 0>, 0> MyExample;
      int a = MyExample::size;
      return 0;
  }
  

Problem summary

• PROBLEM DESCRIPTION: incomplete class error issued for member
  template
  
  USERS AFFECTED: An initializer for a static const member of a
  member template requires an instantiation of the same template.
    The compiler was processing the initializer before the
  instantiation, but the initializer requires the instantiation.
   The result was an incomplete class error for a missing
  instantiation.
  

Problem conclusion

• Problem is fixed. The missing instantiation is completed before
  processing the initializer.
  

Temporary fix

Comments

APAR Information

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

  LI77283

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

Fix information

• Fixed component name

  XL C/C++ FOR LI

• Fixed component ID

  5725C7300

Applicable component levels

• RC10 PSN LI77283

     UP06/09/13