syntax_data: {"ast_node_type":"other","tokens":[{"end":57,"kind":"keyword","start":0,"text":"if"}]}
source_snippet:                     if !a_auto_traits.contains(&def_id) {
context_before:                 ty::ExistentialPredicate::AutoTrait(def_id) => {
context_after:                         return Err(SelectionError::Unimplemented);