{"ast_node_type":"other","tokens":[{"end":55,"kind":"keyword","start":0,"text":"span_stacks:"}]}
    span_stacks: SmallVec<[SmallVec<[MirSpan; 3]>; 3]>,
    /// truncate them, and we want the correct span to be reported.
    pub(crate) ty: Binders<Ty>,