Macro rustc_expand::expand::ast_fragments

macro_rules! ast_fragments {
    (
        $($Kind:ident($AstTy:ty) {
            $kind_name:expr;
            $(one fn $mut_visit_ast:ident; fn $visit_ast:ident;)?
            $(many fn $flat_map_ast_elt:ident; fn $visit_ast_elt:ident($($args:tt)*);)?
            fn $make_ast:ident;
        })*
    ) => { ... };
}