Common Rust Lifetime Misconceptions (2020)
Common Rust Lifetime Misconceptions (2020)
github.com /pretzelhammer/rust-blog/blob/master/posts/common-rust-lifetime-misconceptions.md
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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Just a quick question, isn't point 8 outdated (misconctption: “Rust borrow checker does adanced liftime analysis”) due to the introduction NLL (no lexical lifetime) in Rust 2018?
There are still obvious things the BC cannot get. For example:
struct Foo; impl Foo { fn num(&mut self) -> usize { 0 } fn index(&mut self, _i: usize) { } } let foo = Foo; foo.index(foo.num()); //errorThis looks like a pretty easy fix that the compiler could do by extracting the argument to a temp variable to improve the syntax of the language.
Note that when you change
numto take&selfinstead, this works out (you also need to markfooas mutable, of course).It's a toy example. In that case, the solution is to assign the expression to a variable to compute its result upfront.