如何用循环创建Tauri的SystemTrayMenu（修复编译错误）

问题背景 #

我有PHP开发经验，习惯在循环中调用并修改数据，但这种写法在Rust里无法生效。需要修改以下Tauri代码，使其能编译并得到正确结果，我自己尝试修改后未达到预期效果。

依赖配置（Cargo.toml） #

[build-dependencies]
tauri-build = { version = "1.2", features = [] }

[dependencies]
tauri = { version = "1.2", features = ["icon-png", "shell-open", "system-tray"] }

原代码 #

use tauri::{CustomMenuItem, SystemTray, SystemTrayMenu, SystemTrayMenuItem, SystemTraySubmenu};

pub fn menu() -> SystemTray {
    let tray_menu = SystemTrayMenu::new()
        .add_native_item(SystemTrayMenuItem::Separator)
        .add_submenu(SystemTraySubmenu::new(
            "Setting",
            SystemTrayMenu::new()
                .add_item(CustomMenuItem::new(
                    "edit_config".to_string(),
                    "Edit config",
                ))
                .add_item(CustomMenuItem::new(
                    "reload_config".to_string(),
                    "Reload config",
                ))
                .add_item(CustomMenuItem::new("quit".to_string(), "Quit")),
        ));

    for i in 0..55 {
        let si = i.to_string();
        &tray_menu.add_item(CustomMenuItem::new(
            "id_".to_string() + &si,
            "m".to_string() + &si,
        ));
    }
    SystemTray::new().with_menu(tray_menu)
}

编译错误信息 #

error[E0382]: use of moved value: `tray_menu`
  --> src/tray.rs:24:10
   |
6  |     let tray_menu = SystemTrayMenu::new()
   |         --------- move occurs because `tray_menu` has type `SystemTrayMenu`, which does not implement the `Copy` trait
...
22 |     for i in 0..55 {
   |     -------------- inside of this loop
23 |         let si = i.to_string();
24 |         &tray_menu.add_item(CustomMenuItem::new(
   |          ^^^^^^^^^ value moved here, in previous iteration of loop
   |
help: consider cloning the value if the performance cost is acceptable
   |
24 |         &tray_menu.clone().add_item(CustomMenuItem::new(
   |                   ++++++++

For more information about this error, try `rustc --explain E0382`.

尝试过的无效修改 #

我按照提示尝试了clone，但修改后的代码并未生效——每次clone都会生成新的临时实例，原菜单根本没被修改：

&tray_menu.clone().add_item(CustomMenuItem::new(
    "id_".to_string() + &si,
    "m".to_string() + &si,
));

正确解决方案 #

核心原因 #

Rust的所有权机制决定了SystemTrayMenu::add_item方法会获取当前菜单实例的所有权，并返回一个包含新项的新菜单实例。原代码中直接调用tray_menu.add_item会导致原变量的所有权被转移，循环第二次执行时就会报错；而clone的方式只是修改临时副本，原菜单不会有任何变化。

修改后的代码 #

use tauri::{CustomMenuItem, SystemTray, SystemTrayMenu, SystemTrayMenuItem, SystemTraySubmenu};

pub fn menu() -> SystemTray {
    // 将tray_menu声明为可变变量
    let mut tray_menu = SystemTrayMenu::new()
        .add_native_item(SystemTrayMenuItem::Separator)
        .add_submenu(SystemTraySubmenu::new(
            "Setting",
            SystemTrayMenu::new()
                .add_item(CustomMenuItem::new(
                    "edit_config".to_string(),
                    "Edit config",
                ))
                .add_item(CustomMenuItem::new(
                    "reload_config".to_string(),
                    "Reload config",
                ))
                .add_item(CustomMenuItem::new("quit".to_string(), "Quit")),
        ));

    for i in 0..55 {
        let si = i.to_string();
        // 将add_item返回的新菜单实例重新赋值给tray_menu
        tray_menu = tray_menu.add_item(CustomMenuItem::new(
            format!("id_{si}"),
            format!("m_{si}"),
        ));
    }
    SystemTray::new().with_menu(tray_menu)
}

修改说明 #

1. 将let tray_menu改为let mut tray_menu，允许变量被重新赋值；
2. 循环中不再使用引用或clone，而是直接把add_item返回的新菜单实例赋值给tray_menu，这样每次循环都会更新菜单实例；
3. 使用format!宏简化字符串拼接，比to_string() + &si更简洁。

内容的提问来源于stack exchange，提问作者InSun Lee