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Common Rust Lifetime Misconceptions (2020) (github.com)

submitted 1 year ago by [email protected] to c/[email protected]

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[–] [email protected] 5 points 1 year ago (4 children)

That's a very nicecly written article.

Just a quick question, isn't point 8 outdated (misconctption: “Rust borrow checker does adanced liftime analysis”) due to the introduction NLL (no lexical lifetime) in Rust 2018?

[–] [email protected] 1 points 1 year ago* (last edited 1 year ago) (3 children)

There are still obvious things the BC cannot get. For example:

struct Foo;

impl Foo {
    fn num(&amp;mut self) -> usize { 0 }
    fn index(&amp;mut self, _i: usize) { }
}

let foo = Foo;
foo.index(foo.num()); //error

[–] [email protected] 1 points 1 year ago* (last edited 1 year ago) (1 children)

Note that when you change num to take &self instead, this works out (you also need to mark foo as mutable, of course).

[–] [email protected] 1 points 1 year ago

It's a toy example. In that case, the solution is to assign the expression to a variable to compute its result upfront.

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