Creduce bug

/*
Commandline:
creduce --no-default-passes --add-pass pass_clang template-non-type-arg-to-int 10  `which true` file2.ii

Output:

creduce 2.5.0
18e04be
Linux
Workstation
4.8.0-36-generic
#36~16.04.1-Ubuntu SMP Sun Feb 5 09:39:57 UTC 2017
x86_64

***************************************************

pass_clang::template-non-type-arg-to-int has encountered a bug:
pass failed to modify the variant

Please consider tarring up .../Workspace_creduce/creduce_bug_001
and mailing it to creduce-bugs@flux.utah.edu and we will try to fix
the bug.

This bug is not fatal, C-Reduce will continue to execute.

***************************************************
 */

template <bool>
struct enable_if;
template <class _Tp, int __v>
struct integral_constant {
  static const int value  ;
};
struct is_abstract
    : integral_constant<bool, __is_abstract(int)> {};
struct is_convertible
    : integral_constant<bool, __is_convertible_to(int, int) > {};
template <class _Tp, class... _Args>
struct is_constructible
    : integral_constant<bool, __is_constructible(_Tp, _Args...)> {};
template <class , class _T2>
struct pair {
  typedef _T2 second_type;
  _T2 second;
  template <bool _Val> using _EnableB = typename enable_if<_Val>::type;
  struct _CheckArgs {
    template <class , class _U2> constexpr bool __enable_implicit() {
      return is_constructible<second_type, _U2>::value;
    }
  };
  template <class _U1, class _U2,
            _EnableB<_CheckArgs::template __enable_implicit<
                _U1 , _U2 &>()> = false>
  pair(pair<_U1, _U2> ) ;
};

namespace ADT {
class FS {
public:
  virtual ~FS();
  virtual double gethighA() const ;
  virtual double getlowA() const ;
};
}
namespace ADTImpl {
class FS : public ADT::FS {
double _highA;
  double _lowA;
  double gethighA() const;
  double getlowA() const;
};

union __value_type {
  pair<int, FS> __cc;
};

}