syntax_data: {"ast_node_type":"other","tokens":[{"end":48,"kind":"keyword","start":0,"text":"if"}]}
source_snippet:     if !is_empty_match && all_arms_have_guards {
context_before:     let all_arms_have_guards = arms.iter().all(|arm_id| thir[*arm_id].guard.is_some());
context_after:         err.subdiagnostic(NonExhaustiveMatchAllArmsGuarded);