title: Arrays as function parameters in numba
body: <p>Following simple example fails with an error:</p>
  
  <p>Standalone module:</p>
  
  <pre><code>from numba.pycc import CC
  
  cc = CC('foo')
  
  @cc.export('product','float64(float64[:], float64[:])')
  def product(a, b):
      prod = 0
      for i in range(a.size):
          prod += a[i] * b[i]
      return prod
  
  if __name__ == "__main__":
      cc.compile()
  </code></pre>
  
  <p>The test program:</p>
  
  <pre><code>import numpy as np
  import foo
  
  x = np.array([2,3,1,0])
  y = np.array([2,3,1,0])
  
  print(foo.product(x,y))
  </code></pre>
  
  <p>Fails with error message:</p>
  
  <pre><code>Traceback (most recent call last):
    File "\temp\test.py", line 7, in &lt;module&gt;
      print(foo.product(x,y))
  SystemError: exception RuntimeError&lt;class 'BytesWarning'&gt; not a BaseException subclass
  </code></pre>
  
  <p>Used numba version is 0.42.0 and Python 3.7.2 on Windows.
  Any hints?</p>