[Bug c++/70106] [4.9/5.3/6.0][C++11 or above] adding parenthesis [cerr << (var)] cause error: invalid static_cast from type 'const size_t {aka const long unsigned int}' to type 'size_t& {aka long unsigned int&}'

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70106

--- Comment #2 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Oops, wrong reduction.  struct A has to be a template.


template <class T>
struct A
{
  int x;

  void foo () const {
    (A::x);
  };
};

void
foo ()
{
  A<int> ().foo ();
}