此问题在此处已有答案：

Expected closure, found a different closure（2个答案）
4天前关闭。
如何将两个具有相同定义的闭包放入Vec中？
下面是一个最小可重复的示例：

fn main() {
    let mut vec = Vec::new();
    vec.push(Box::new(|| println!("test")));
    vec.push(Box::new(|| println!("test2")));
    
    vec.iter().for_each(|f| (f)());
}

字符串
编译失败，出现以下错误：

error[E0308]: mismatched types
 --> src/main.rs:4:23
  |
3 |     vec.push(Box::new(|| println!("test")));
  |                       -- the expected closure
4 |     vec.push(Box::new(|| println!("test2")));
  |              -------- ^^^^^^^^^^^^^^^^^^^^ expected closure, found a different closure
  |              |
  |              arguments to this function are incorrect
  |
  = note: expected closure `[closure@src/main.rs:3:23: 3:25]`
             found closure `[closure@src/main.rs:4:23: 4:25]`
  = note: no two closures, even if identical, have the same type
  = help: consider boxing your closure and/or using it as a trait object

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