new_contents: from nose.tools import raises
  import tvm
  
  @raises(Exception)
  def test_loop_dependent_allocate():
      N = tvm.var("N")
      A = tvm.placeholder((2*N,), "float32", "A")
      C = tvm.compute((N, ), lambda i: A[2*i] + A[i+1], name='C')
      s = tvm.create_schedule(C.op)
      AA = s.cache_read(A, "local", [C])
      s[AA].compute_at(s[C], s[C].op.axis[0])
      # this line should fail due to IRUseDefAnalysis sees an allocate statement
      # referencing undefined variable
      tvm.lower(s, [A,C])
  
  if __name__ == "__main__":
      test_loop_dependent_allocate()
  
subject: Add test to confirm that we forbid allocate statement referencing undefined variable (#1899)