title: Cython compilation error "Not allowed in a constant expression"
body: <p>The following</p>
  <pre><code>cimport cython
  
  @cython.boundscheck(False)
  def boundtest():
       cdef int r=4
       cdef double l[3]
  </code></pre>
  <p>works fine. But when I try this:</p>
  <pre><code>cimport cython
  
  @cython.boundscheck(False)
  def boundtest():
       cdef int r=4
       cdef double l[r]
  </code></pre>
  <p>I receive the following error:</p>
  <pre><code>[1/1] Cythonizing test.pyx
  
  Error compiling Cython file:
  ------------------------------------------------------------
  ...
  cimport cython
  
  @cython.boundscheck(False)
  def boundtest():
       cdef int r=4
       cdef double l[r]
                     ^
  ------------------------------------------------------------
  
  test.pyx:13:20: Not allowed in a constant expression
       
  </code></pre>
  <p>The decorator was added due to finding <a href="https://stackoverflow.com/questions/25917593/how-to-declare-2d-c-arrays-dynamically-in-cython">this</a> related stackexchange post and reading the Cython book by Kurt W. Smith. As far as I can tell this should work to tell Cython not to worry about out of bounds errors that may result from having a dynamic indexing variable but for some reason it does not. I have also tried changing boundscheck in the compiler options and globally to no avail.</p>
  <p>If it weren't for the Cython documentation claiming to be up to date I would think boundscheck has been depreciated.</p>