syntax_data: {"ast_node_type":"other","tokens":[{"end":59,"kind":"keyword","start":0,"text":"err.subdiagnostic(FeatureDiagnosticForIssue"}]}
source_snippet:         err.subdiagnostic(FeatureDiagnosticForIssue { n });
context_before:     if let Some(n) = find_feature_issue(feature, issue) {
context_after:     }