Error with Cpp compiled expression

I/O
1

I am trying to convert the following python UserExpression class for inflow boundary condition to C++ to make it more efficient.

class Inflow(UserExpression):

  def __init__(self, param, mesh, **kwargs):
            super(Inflow, self).__init__(**kwargs)
            self.param = param
            self.mesh = mesh

  def eval_cell(self, values, x, ufc_cell):

      # Create DOLFIN Cell
      cell = Cell(self.mesh, ufc_cell.index)
      
      # Get normal for current facet
      assert(ufc_cell.local_facet >= 0)
      n = cell.normal(ufc_cell.local_facet)
      
      # Compute boundary value
      t = self.param["time"].t
      period = self.param["period"]
      nm = self.param["nm"].cycle
      Area = self.param["Area"]
      Vsc = self.param["Vsc"]
      Tsc = self.param["Tsc"]
      func = self.param["func"]

      val = (splev(t*Tsc - nm*period*Tsc, func)/Area)/Vsc
      values[0] = -n.x()*val
      values[1] = -n.y()*val
      values[2] = -n.z()*val 

  def value_shape(self):
      return (3,)

Here is my C++ code for the same class:

   def Inflow1(param, mesh, degree):

      t = param["time"].t
      period = param["period"]
      nm = param["nm"].cycle
      Area = param["Area"]
      Vsc = param["Vsc"]
      Tsc = param["Tsc"]
      func = param["func"]  
      val = (splev(t*Tsc - nm*period*Tsc, func)/Area)/Vsc

      code = '''
      #include <dolfin/function/Expression.h>
      
      using namespace dolfin;
  
      class InflowX : public Expression
      {
      public:
          double v;
          InflowX() : Expression(3) {}
  
      void eval(Array<double>& values, const Array<double>& x,
                const ufc::cell& c) const
        {
          const Cell cell(*cell_data->mesh(), c.index);
          assert(c.local_facet >= 0);
          
          double n_x cell.normal(c.local_facet, 0);
          double n_y cell.normal(c.local_facet, 1);
          double n_z cell.normal(c.local_facet, 2);
  
          values[0] = -1*n_x*v  
          values[1] = -1*n_y*v
          values[2] = -1*n_z*v
        }
      };'''
  
      f = Expression(code, domain = mesh, degree = degree)
      f.v = val
  
      return f

This seems to be producing the following error.

File “/usr/local/lib/python3.6/dist-packages/dolfin/jit/jit.py”, line 170, in compile_class
raise RuntimeError(“Unable to compile C++ code with dijitso”)
RuntimeError: Unable to compile C++ code with dijitso

Any help to resolve this error would be appreciated? Thanks in advance.