'pointer to unimplemented type' error

[prashant rawat]

Hello,
I have to add a data structure to cgraph_node structure. My data
structure is a pointer to tree node.
If I add tree* abc to cgraph_node, I get an error  'field `(*x).abc'
is pointer to unimplemented type'
Does this mean that I cannot add pointer-to pointer data structures to
cgraph_node?
If anyone faced a similar problem, any suggested workaround to
alleviate this issue?
Thanks!