{"ast_node_type":"variable","tokens":[{"end":89,"kind":"keyword","start":0,"text":"if"}]}
    if let TerminatorKind::Unreachable = body.basic_blocks[START_BLOCK].terminator().kind
    // More generally, if MIR is a lone `unreachable`, there is nothing to optimize.
        && body.basic_blocks[START_BLOCK].statements.is_empty()