IV37950: TEMPLATE NOT ACCEPTING DEFAULT PARAM FUNCTION

March 2013 PTF for XL C/C++ for AIX, V12.1
XL C/C++ for AIX Fix Pack 4 (June 2013 PTF) for 12.1
XL C/C++ for AIX Fix Pack 5 (September 2013 PTF) for 12.1
XL C/C++ for AIX Fix Pack 7 (January 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 8 (March 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 11 (February 2015 PTF) for 12.1
XL C/C++ for AIX Fix Pack 12 (May 2015 PTF) for 12.1
XL C/C++ for AIX Fix Pack 13 (August 2015 Update) for 12.1
XL C/C++ for AIX Fix Pack 14 (December 2015 Update) for 12.1
XL C/C++ for AIX Fix Pack 15 (April 2016 Update) for 12.1
XL C/C++ for AIX Fix Pack 16 (July 2016 Update) for 12.1
XL C/C++ for AIX Fix Pack 17 (November 2016 Update) for 12.1
XL C/C++ for AIX Fix Pack 18 (February 2017 Update) for 12.1
XL C/C++ for AIX Fix Pack 19 (August 2017 Update) for 12.1
XL C/C++ for AIX Fix Pack 20 (March 2018 Update) for 12.1
XL C/C++ for AIX Fix Pack 6 (December 2013 PTF) for 12.1
XL C/C++ for AIX Fix Pack 9 (July 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 10 (October 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 21 (January 2019 Update) for 12.1

APAR status

• Closed as program error.

Error description

• An implicit template instantiation with explicit specialization,
  using a pointer to a function with a default parameter is
  encountering an invalid error during compile.
  
  
       =====  TEST CASE  =====
  
  template <typename T>
  struct myTemplate       { typedef T type; };
  
  template <typename T>
  struct myTemplate<T *>  { typedef T type; };
  
  void defaultarg(int = 0);
  
  template <typename T>
  void templateFunction(T)
  {
     typedef typename myTemplate<T>::type template_type;
  }
  
  void test()
  {
     templateFunction(&defaultarg);
  }
  
  
  $ xlC -c test.cpp
  1540-1111 (S) Only function declarations can have default
  arguments.
  "test.cpp", line 12.13: 1540-0700 (I) The previous message was
  produced while processing "struct myTemplate<void (*)(int)>".
  "test.cpp", line 10.6: 1540-0700 (I) The previous message was
  produced while processing "templateFunction<void (*)(int)>(void
  (*)(int))".
  "test.cpp", line 17.9: 1540-0700 (I) The previous message was
  produced while processing "test()".
  $
  

Local fix

• The issue can be worked around by using an explicit template
  instantiation.
  

Problem summary

• PROBLEM DESCRIPTION:
  Template argument deduction including default arguments in an
  invalid context.
  
  USERS AFFECTED:
  The problem is specific to the use of argument deduction when
  passing a function type to a template function, where the
  function type has a default argument.
  

Problem conclusion

• The problem has been resolved.
  

Temporary fix

Comments

APAR Information

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

  IV33204

• 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