返回值的Rust生存期应等于结构的生存期

问题描述

假设我有这样的代码：

struct Struct0 {
   s1: Struct1,v: Vec<Box<dyn Tr>>
}

impl Struct0 {
    fn a(&mut self) {
        self.v = self.s1.func();
    }
}

struct Struct1 {}

impl<'a> Struct1 {
    fn func(&'a self) -> Vec<Box<dyn Tr + 'a>> {
        vec![Box::new(Struct2 { some_reference: &self } )]
    }
}

trait Tr {
    //...
}

struct Struct2<'a> {
   some_reference: &'a Struct1
}

impl Tr for Struct2<'_> {
    //...
}

fn main() {
    
}

这会出现以下错误：

error[E0495]: cannot infer an appropriate lifetime for autoref due to conflicting requirements
 --> src/main.rs:8:26
  |
8 |         self.v = self.s1.func();
  |                          ^^^^
  |
note: first,the lifetime cannot outlive the anonymous lifetime #1 defined on the method body at 7:5...
 --> src/main.rs:7:5
  |
7 | /     fn a(&mut self) {
8 | |         self.v = self.s1.func();
9 | |     }
  | |_____^
note: ...so that reference does not outlive borrowed content
 --> src/main.rs:8:18
  |
8 |         self.v = self.s1.func();
  |                  ^^^^^^^
  = note: but,the lifetime must be valid for the static lifetime...
note: ...so that the expression is assignable
 --> src/main.rs:8:18
  |
8 |         self.v = self.s1.func();
  |                  ^^^^^^^^^^^^^^
  = note: expected `std::vec::Vec<std::Boxed::Box<(dyn Tr + 'static)>>`
             found `std::vec::Vec<std::Boxed::Box<dyn Tr>>`

我想告诉Rust编译器，返回值的生存期应该是Struct1的生存期。该向量（及其值）应与调用该方法的结构一样长。我怎么说呢？

解决方法

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lifetime methods