syntax_data: {"ast_node_type":"other","tokens":[{"end":49,"kind":"keyword","start":0,"text":"write!(p,"}]}
source_snippet:                 write!(p, "unstable feature: ")?;
context_before:             ty::ClauseKind::UnstableFeature(symbol) => {
context_after:                 write!(p, "`{symbol}`")?;