Rust函数返回Vec<&str>时生命周期错误的解决方法

初始实现代码 #

use std::fs;

fn read_input_file(input_file: String, path_list: &mut Vec<&str>) {
    let output_file =
        fs::read_to_string(input_file).expect("Should have been able to read the file");
    *path_list = output_file.split('\n').collect::<Vec<&str>>();
}

编译器报错 #

error[E0597]: output_file does not live long enough
--> src\main.rs:112:18
|
109 | fn read_input_file(input_file: String, path_list: &mut Vec<&str>) {
| - let's call the lifetime of this reference '1
...
112 | *path_list = output_file.split('\n').collect::<Vec<&str>>();
| ---------- ^^^^^^^^^^^^^^^^^^^^^^^ borrowed value does not live long enough
| |
| assignment requires that output_file is borrowed for '1
113 | }
| - output_file dropped here while still borrowed

尝试添加生命周期的修改代码 #

use std::fs;
use std::str::Split;

fn read_input_file<'a, 'b>(input_file: String, path_list: &'a mut Vec<&str>) {
    let output_file =
        fs::read_to_string(input_file).expect("Should have been able to read the file");
    let split: &'b Split<'_, char> = &output_file.split('\n');
    *path_list = (*split.clone().collect::<Vec<&str>>()).to_vec();
}

再次报错 #

error[E0597]: output_file does not live long enough
--> src\main.rs:105:39
|
102 | fn read_input_file<'a, 'b>(input_file: String, path_list: &'a mut Vec<&str>) {
| -- lifetime 'b defined here
...
105 | let split: &'b Split<'_, char> = &output_file.split('\n');
| ------------------- ^^^^^^^^^^^^^^^^^^^^^^^ borrowed value does not live long enough
| |
| type annotation requires that output_file is borrowed for 'b
106 | *path_list = (*split.clone().collect::<Vec<&str>>()).to_vec();
107 | }
| - output_file dropped here while still borrowed

error[E0716]: temporary value dropped while borrowed
--> src\main.rs:105:39
|
102 | fn read_input_file<'a, 'b>(input_file: String, path_list: &'a mut Vec<&str>) {
| -- lifetime 'b defined here
...
105 | let split: &'b Split<'_, char> = &output_file.split('\n');
| ------------------- ^^^^^^^^^^^^^^^^^^^^^^^ creates a temporary value which is freed while still in use
| |
| type annotation requires that borrow lasts for 'b
106 | *path_list = (*split.clone().collect::<Vec<&str>>()).to_vec();
107 | }
| - temporary value is freed at the end of this statement

问题本质与解决方案 #

核心问题：output_file是函数内的局部变量，函数执行结束后会被销毁，但你试图传递的Vec<&str>里的所有引用都指向它的内容，这会产生悬垂引用，Rust的所有权系统严格禁止这种不安全的行为。

以下是两种正确的处理方式：

方案1：返回Vec<String>（推荐） #

将分割后的字符串转为拥有所有权的String，彻底摆脱对局部变量生命周期的依赖，代码简洁且安全：

use std::fs;

// 直接返回Vec<String>
fn read_input_file(input_file: String) -> Vec<String> {
    let output_file = fs::read_to_string(input_file).expect("Failed to read file");
    output_file.split('\n').map(|s| s.to_string()).collect()
}

// 或者用可变引用参数传递结果
fn read_input_file(input_file: String, path_list: &mut Vec<String>) {
    let output_file = fs::read_to_string(input_file).expect("Failed to read file");
    *path_list = output_file.split('\n').map(|s| s.to_string()).collect();
}

方案2：让字符串容器生命周期超出函数范围 #

如果必须使用Vec<&str>，需要让存储原始字符串的容器（比如String）的生命周期覆盖Vec<&str>的使用周期。可以通过将字符串作为可变参数传入函数实现：

use std::fs;

fn read_input_file<'a>(input_file: String, content: &'a mut String) -> Vec<&'a str> {
    *content = fs::read_to_string(input_file).expect("Failed to read file");
    content.split('\n').collect()
}

// 调用示例
fn main() {
    let mut file_content = String::new();
    let path_list = read_input_file("input.txt".to_string(), &mut file_content);
    // 注意：file_content必须保持存活，path_list才能有效使用
}

内容的提问来源于stack exchange，提问作者Jerome