syntax_data: {"ast_node_type":"other","tokens":[{"end":13,"kind":"keyword","start":0,"text":"("}]}
source_snippet:             (
context_before:         let (self_ty, impl_trait_ref) = if tcx.generics_of(impl_def_id).count() <= args.len() {
context_after:                 self_ty.instantiate(tcx, args),