freeing error attribute data malloced in lex

[anton wilson]

If lex mallocs attribute data for a token and returns that token to bison,
and that token ends up causing an error, how do i free the malloced data from 
bison? Is there anyway to reach that data, or is it better to keep track of 
malloced data from within lex, so I can free it in the recovery function?
Similarly, how do I free any data that may correspond to the lookahead token 
(if such a thing exists).

Anton