LI74345: INCORRECT SIZEOF OPERATOR OUTPUT

March 2009 Update for XL C/C++ for Linux, V10.1
October 2009 Update for XL C/C++ for Linux, V10.1
June 2011 Update for XL C/C++ for Linux, V10.1
XL C/C++ for Linux Fix Pack 8 (January 2014 Update) for 10.1
August 2010 Update for XL C/C++ for Linux, V10.1
January 2011 Update for XL C/C++ for Linux, V10.1
January 2012 Update for XL C/C++ for Linux, V10.1
July 2012 Update for XL C/C++ for Linux, V10.1

APAR status

• Closed as program error.

Error description

• When compiling the following test case, the result of the sizeof
  operator inside the template class is incorrect.
  
  
  -------------------------------------
  
  To Compile:  xlC test.C
  
  ============  TEST CASE  ============
  
  extern "C" int printf(const char * , ...);
  
  template <class type>
  struct tempfoo {
      enum { SIZE = sizeof(type) };
  };
  
  struct foo {
      struct Values {
          double V1,V2,V3,V4;
      };
  
      typedef tempfoo<Values> Some_type;
      Some_type Null_T;
  
      typedef tempfoo<Values> Some_type2;
  
      struct Values2 { Some_type2 Var_name; };
  };
  
  int main() {
      printf("SIZE = %d, should be %d\n", foo::Some_type2::SIZE,
  sizeof(foo::Values));
  
      return 1;
  }
  

Local fix

Problem summary

• USER AFFECTED:
  Users creating classes with multiple templated variables, of the
  same type, that get instantiated more than once in a class (ie,
  the template class uses a template parameter to calculate
  sizeof).
  
  PROBLEM DESCRIPTION:
  Compiler incorrectly returns information about the template
  parameter which is not yet fully instantiated (ie, sizeof will
  return nonsense rather than the actual size).
  

Problem conclusion

• Fixed how templates are instantiated so that this scenario is
  considered, and correct program output is observed.
  

Temporary fix

Comments

APAR Information

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

  LI74299

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

Fix information

• Fixed component name

  XL C/C++ RHEL52

• Fixed component ID

  5724U8310

Applicable component levels

• RA10 PSN LI74299

     UP06/09/13