struct - 在以下上下文中如何解决 "lifetime of reference outlives lifetime of borrowed content"？

Question

我的 lib.rs 中有以下结构

pub enum ConfigurationSource {
    StringContent(String),
    FileContent(PathBuf)    
}

pub struct ConfigurationBuilder<'a> {
    config: Value,
    bundles: HashMap<&'a str, &'a Vec<ConfigurationSource>>    
}

impl<'a> ConfigurationBuilder<'a>{
    pub fn new(base_source: &ConfigurationSource) -> ConfigurationBuilder{
        let base_config: Value = from_str("{}").unwrap();

        let mut config_builder = ConfigurationBuilder{
            config: base_config,
            bundles: HashMap::new()
        };

        config_builder.merge_source(&base_source);

        return config_builder;
    }

    //more code here

    pub fn define_bundle(&mut self, bundle_key: &str, sources: &Vec<ConfigurationSource>){
        self.bundles.insert(bundle_key, sources);
    }
}

我不希望 ConfigurationBuilder 实例中的 bundle Hashmap 拥有传递给 define_bundle 方法的 bundle_key 或 source。

我在构建时遇到以下两个编译错误

error[E0312]: lifetime of reference outlives lifetime of borrowed content...
  --> src\lib.rs:67:41
   |
67 |         self.bundles.insert(bundle_key, sources);
   |                                         ^^^^^^^
   |
note: ...the reference is valid for the lifetime 'a as defined on the impl at 27:1...
  --> src\lib.rs:27:1
   |
27 | / impl<'a> ConfigurationBuilder<'a>{
28 | |
29 | |     pub fn new(base_source: &ConfigurationSource) -> ConfigurationBuilder{
30 | |         let base_config: Value = from_str("{}").unwrap();
...  |
89 | |     }
90 | | }
   | |_^
note: ...but the borrowed content is only valid for the anonymous lifetime #3 defined on the method
 body at 66:5
  --> src\lib.rs:66:5
   |
66 | /     pub fn define_bundle(&mut self, bundle_key: &str, sources: &Vec<ConfigurationSource>){
67 | |         self.bundles.insert(bundle_key, sources);
68 | |     }
   | |_____^

error[E0312]: lifetime of reference outlives lifetime of borrowed content...
  --> src\lib.rs:67:29
   |
67 |         self.bundles.insert(bundle_key, sources);
   |                             ^^^^^^^^^^
   |
note: ...the reference is valid for the lifetime 'a as defined on the impl at 27:1...
  --> src\lib.rs:27:1
   |
27 | / impl<'a> ConfigurationBuilder<'a>{
28 | |
29 | |     pub fn new(base_source: &ConfigurationSource) -> ConfigurationBuilder{
30 | |         let base_config: Value = from_str("{}").unwrap();
...  |
89 | |     }
90 | | }
   | |_^
note: ...but the borrowed content is only valid for the anonymous lifetime #2 defined on the method
 body at 66:5
  --> src\lib.rs:66:5
   |
66 | /     pub fn define_bundle(&mut self, bundle_key: &str, sources: &Vec<ConfigurationSource>){
67 | |         self.bundles.insert(bundle_key, sources);
68 | |     }
   | |_____^

我做错了什么？

Answer 1

define_bundle 的输入参数的生命周期编译器不知道是否满足或超过为结构定义的参数。

告诉编译器他们期望相同的生命周期就可以了:

pub fn define_bundle(&mut self, bundle_key: &'a str, sources: &'a Vec<ConfigurationSource>) {
    //                                       ^^----------------^^ same lifetimes as the struct fields expect
    self.bundles.insert(bundle_key, sources);
}