Draft: [FIX] Index fields exclusively containing coordinates are dropped by code generator

Index fields that exclusively contain coordinate data (members x, y and z) and that are not explicitly accessed in the kernel assignments are dropped by pystencils.cpu.create_indexed_kernel in cpu/kernelcreation.py, prev. line 119. Then in line 128 the list of index fields is empty, and the code generator finds no field containing the coordinate information. Code generation then aborts.

Is there a reason why index fields are first filtered this way?

pystencils/cpu/kernelcreation.py

@@ -115,8 +115,6 @@ def create_indexed_kernel(assignments: NodeCollection,
     fields_read = assignments.rhs_fields
 
     all_fields = fields_read.union(fields_written)
-    # extract the index fields based on the name. The original index field might have been modified
-    index_fields = [idx_field for idx_field in index_fields if idx_field.name in [f.name for f in all_fields]]
     non_index_fields = [f for f in all_fields if f not in index_fields]
     spatial_coordinates = {f.spatial_dimensions for f in non_index_fields}
     assert len(spatial_coordinates) == 1, f"Non-index fields do not have the same number of spatial coordinates " \