rust-lang / rust-lang/nomicon

Confused about lifetime

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#442 0 comments 0 reactions 0 assignees View on GitHub

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Dominant language
CSS
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Description

let x = 0;
let z;
let y = &x;
z = y;
'a: {
    let x: i32 = 0;
    'b: {
        let z: &'b i32;
        'c: {
            // Must use 'b here because the reference to x is
            // being passed to the scope 'b.
            let y: &'b i32 = &'b x;
            z = y;
        }
    }
}

Why mark y with 'b, but not z with 'c? Are there any references on lifetime eval?

Contributor guide

No contributing guide indexed for this repository

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the lifetime example and desugared Rust code in issue #442, then consult the Nomicon material on lifetime evaluation and the references it links. Done means explaining why y uses 'b while z does not use 'c, and identifying the documentation location that should be clarified; no file or test is named in the issue.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
documentation
Issue type
Documentation
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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