syntax_data: {"ast_node_type":"other","tokens":[{"end":61,"kind":"keyword","start":0,"text":"(&ty::Adt(def,"}]}
source_snippet:             (&ty::Adt(def, args_a), &ty::Adt(_, args_b)) => {
context_before:             // `Struct<T>` -> `Struct<U>`
context_after:                 let unsizing_params = tcx.unsizing_params_for_adt(def.did());