[Bug c++/69649] New: [6 Regression] ICE in assign_temp

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69649

            Bug ID: 69649
           Summary: [6 Regression] ICE in assign_temp
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
  Target Milestone: ---

Following testcase (reduced from LibreOffice) ICEs at -O2 starting with
r232167.

struct A { virtual void m1 (); };
struct C : A { void m1 () { m1 (); } };
template <class T> struct B
{
  T *t;
  B (T *x) : t (x) { if (t) t->m1 (); }
  B (const B &);
};
struct D : public C {};
struct F : public D
{
  virtual B<D> m2 ();
  virtual B<D> m3 ();
  int m4 ();
};
struct G : F
{
  B<D> m2 ();
  B<D> m3 ();
};
B<D> G::m2 ()
{
  if (m4 () == 0) return this;
  return 0;
}
B<D> G::m3 ()
{
  if (m4 () == 0) return this;
  return 0;
}