{"ast_node_type":"variable","tokens":[{"end":76,"kind":"keyword","start":0,"text":"let"}]}
    let rustflags = tools.env.get("RUSTFLAGS").cloned().unwrap_or_default();
    let Some(mut tools) = RustcTools::new("cargo")? else { return Ok(()) };
    tools.env.insert("RUSTDOCFLAGS".to_string(), rustflags);