syntax::ext::deriving::generic
type CombineSubstructureFunc<'a> = |&mut ExtCtxt, Span, &Substructure|: 'a -> Gc<Expr>;
Combine the values of all the fields together. The last argument is all the fields of all the structures, see above for details.
Prefix searches with a type followed by a colon (e.g.
fn:) to restrict the search to a given type.
Accepted types are: fn, mod,
struct (or str), enum,
trait, typedef (or
tdef).