LI78288: INTERNAL COMPILER ERROR IN XLCENTRY

XL C/C++ for Blue Gene/Q Fix Pack 12 (May 2015 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 14 (May 2016 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 15 (October 2017 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 11 (February 2015 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 13 (August 2015 Update) for 12.1

APAR status

• Closed as program error.

Error description

• The following test case produces an internal compiler error when
  compiled with the options listed below:
  
  ===== COMPILE COMMAND:
  bgxlc++ bug_template.cpp
  
  ===== TESTCASE:
  $ cat bug_template.cpp
  //notice that if I replace "unsigned" with "int" everything
  works as it
  //should:
  //template <int n> class A{};
  template <unsigned n> class A{};
  
  struct B{
    unsigned n;
  // also swapping the two next lines fixes the problem:
    template <class T> B(T&t);
    template <unsigned n> B(A<n> &p);
  };
  
  // the order of these two definitions on the other hand is
  irrelevant:
  template <unsigned m> B::B(A<m> &p): n(m){}
  template <class T> B::B(T &p): n(1){}
  
  int main(){
    A<1> a;
    B b(a);
    return 0;
  }
  $
  
  
  ===== ACTUAL OUTPUT:
  bgxlc++ bug_template.cpp
  1540-0505 (S) The build failed and there are no messages.
  1540-0527 (I) The build failure may be because of an Internal
  Compiler Error or because a tool failed to generate a message.
  For more information visit:
  http://www.ibm.com/support/docview.wss?uid=swg21110810
  
  ===== EXPECTED OUTPUT:
  Should not produce an internal compiler error.
  

Local fix

• Use "int" instead of "unsigned"
  

Problem summary

• USERS AFFECTED:
  Linux users with more then 1 user defined constructor which are
  template functions within non template class may be affected by
  this issue.
  
  PROBLEM DESCRIPTION:
  When there are more then 1 user defined constructors, multiple
  template instances can be instantiated with the same type. The
  compiler then picks the wrong one and further cannot resolve
  template arguments leading to an internal compiler error.
  

Problem conclusion

• The issue has been solved by selecting the correct template
  instance of the constructor.
  

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:

  IV68023 LI78473

Fix information

• Fixed component name

  XL C/C++ FOR BG

• Fixed component ID

  5799AG100

Applicable component levels