IJ31048: TYPEDEF'ED STRUCT NOT MATCHING TEMPLATE SPECIALIZATION USING POINTER-TO-CLASS-MEMBER TYPE

APAR status

• Closed as program error.

Error description

• A specialization uses a pointer-to-class-data-member ::* type
  for another class template instantiation (struct V).  The
  specialization is matched correctly when the class is a normally
  defined 'struct A', but fails when the class is a typedef'ed
  'typedef struct {...} B'.
  
  
     === TEST CASE ===
  
  extern "C" int printf(const char *, ...);
  
  template <class T>
  struct V
  {
    typedef void y;
  };
  
  //--------------------------------------------
  
  template <class Y, class = void>
  struct I
  {
    enum { v = 1 }; // B is incorrectly instantiating this
  };
  
  template <class Y>
  struct I<Y, typename V<int Y::*>::y>
  {
    enum { v = 0 };   // Both A and B should instantiate this
  };
  
  //--------------------------------------------
  
  struct X { X() {} };
  
  struct A { X x; };
  typedef struct { X x; } B;
  
  int main()
  {
      printf("A %d\n", I<A>::v);
      printf("B %d\n", I<B>::v); // Bad output, 1, should be 0
  }
  

Local fix

• Do not use typedef
  

Problem summary

• USERS AFFECTED:
  Users who have testcases that make use of template
  specializations may run into this issue.
  
  PROBLEM DESCRIPTION:
  The specialization uses a pointer-to-class-data-member ::* type
  for another class template instantiation (struct V).
  The specialization is matched correctly when the class is a
  normally defined 'struct A', but fails when the class is a
  typedef'ed 'typedef struct {...} B'.
  

Problem conclusion

• The compiler has been fixed to handle the above mentioned
  scenario.
  

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:

Fix information

• Fixed component name

  XL C/C++ FOR AI

• Fixed component ID

  5725C7200

Applicable component levels