def test_direct_invalid():
    x1 = X()
    vref = virtual_ref(x1)
    assert vref._state == 'non-forced'
    virtual_ref_finish(vref, x1)
    assert vref._state == 'invalid'
    py.test.raises(InvalidVirtualRef, "vref()")

 def f(n):
     while n > 0:
         myjitdriver.can_enter_jit(n=n)
         myjitdriver.jit_merge_point(n=n)
         xy = XY()
         xy.next1 = lltype.malloc(A, 0)
         xy.next2 = lltype.malloc(A, 0)
         xy.next3 = lltype.malloc(A, 0)
         xy.next4 = lltype.malloc(A, 0)
         xy.next5 = lltype.malloc(A, 0)
         xy.n = n
         exctx.topframeref = vref = virtual_ref(xy)
         if n % 6 == 0:
             xy.next1 = lltype.nullptr(A)
             xy.next2 = lltype.nullptr(A)
             xy.next3 = lltype.nullptr(A)
             externalfn(n)
         n -= 1
         exctx.topframeref = vref_None
         xy.next1 = lltype.nullptr(A)
         xy.next2 = lltype.nullptr(A)
         xy.next3 = lltype.nullptr(A)
         xy.next4 = lltype.nullptr(A)
         xy.next5 = lltype.nullptr(A)
         virtual_ref_finish(vref, xy)
     return exctx.m

 def f():
     vref = virtual_ref(X())
     try:
         vref()
         return 42
     except InvalidVirtualRef:
         return -1

def test_direct_forced():
    x1 = X()
    vref = virtual_ref(x1)
    assert vref._state == 'non-forced'
    assert vref() is x1
    assert vref._state == 'forced'
    virtual_ref_finish(vref, x1)
    assert vref._state == 'forced'
    assert vref() is x1

 def fn(n):
     res = False
     while n > 0:
         myjitdriver.can_enter_jit(n=n)
         myjitdriver.jit_merge_point(n=n)
         xy = XY()
         xy.n = n
         vref = virtual_ref(xy)
         virtual_ref_finish(vref, xy)
         vref() # raises InvalidVirtualRef when jitted
         n -= 1
     return res

 def f(n):
     while n > 0:
         myjitdriver.can_enter_jit(n=n)
         myjitdriver.jit_merge_point(n=n)
         xy = XY()
         xy.n = n
         exctx.topframeref = virtual_ref(xy)
         exctx.later = exctx.topframeref
         n -= 1
         exctx.topframeref = vref_None
         virtual_ref_finish(xy)
     return g()

 def f(n, x, x0, x1, x2, x3, x4, x5, x6, x7, l, s):
     a = A()
     glob.v = vref = virtual_ref(a)
     virtual_ref_finish(vref, a)
     n -= 1
     return n, x, x0, x1, x2, x3, x4, x5, x6, x7, l, s

 def enter(n):
     x = X(n + 10)
     exctx._frame = x
     exctx.topframeref = virtual_ref(x)

 def f():
     return jit.virtual_ref(X())

 def enter(self, frame):
     frame.f_backref = self.topframeref
     self.topframeref = jit.virtual_ref(frame)

def test_direct_2():
    x1 = X()
    vref = virtual_ref(x1)
    virtual_ref_finish(x1)
    assert vref() is x1