syntax_data: {"ast_node_type":"other","tokens":[{"end":12,"kind":"keyword","start":0,"text":"}"}]}
source_snippet:     } else {
context_before:         iter::once(impl_.self_ty.span).chain(trait_args).chain(dummy_spans_for_default_args)
context_after:         bug!("unexpected item for impl {def_id:?}: {item:?}")