{"ast_node_type":"function","tokens":[{"end":65,"kind":"keyword","start":0,"text":"fn"}]}
    fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
impl crate::MirPass<'_> for UnreachablePropagation {
        // Enable only under -Zmir-opt-level=2 as this can make programs less debuggable.