Common Rust Lifetime Misconceptions (2020) - eviltoast
  • robinm@programming.dev
    5·
    1 year ago

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    Just a quick question, isn’t point 8 outdated (misconctption: “Rust borrow checker does adanced liftime analysis”) due to the introduction NLL (no lexical lifetime) in Rust 2018?

    • hairyballs@programming.dev
      1·
      1 year ago

      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()); //error
      • sirdorius@programming.dev
        2·
        1 year ago

        This 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.

      • KillTheMule@programming.dev
        1·
        1 year ago

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

        • hairyballs@programming.dev
          1·
          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.