Document issue with vector access

python/dune/perftool/loopy/target.py

@@ -54,6 +54,14 @@ class DuneASTBuilder(CASTBuilder):
         if temp_var.decl_method:
             return Line(temp_var.decl_method(temp_var.name, temp_var.shape, temp_var.shape_impl))
 
+    def add_vector_access(self, access_expr, index):
+        # There is no generic way of implementing a vector access with VCL, as
+        # it might be that the entire statement needs to be rewritten. Consider
+        # the example of an assignment to a vector component. It is *not* of the
+        # form 'x.0 = 2' but instead its 'x.insert(0, 2)'. It is currently not
+        # clear to me how this can be done, so I avoid the sitauation entirely.
+        raise NotImplementedError()
+
     def emit_barrier(self, kind, comment):
         post_include("#define BARRIER asm volatile(\"\": : :\"memory\")", filetag="operatorfile")
         return Line("BARRIER;")