gcc/testsuite/g++.dg/ext/attribute-may-alias-2.C

// PR c++/53421

template< class T >
struct Y : T
{ } __attribute__((__may_alias__));

struct X
{
  operator Y<X>& ();
};

Y<X> y = Y<X>();
X::operator Y<X>& () { return *static_cast< Y<X>* >(this); }