Hacker News new | ask | show | jobs
by estebank 1281 days ago
Yes, that's true but that is an implementation detail that only comes into play when dealing with ABI, and then you should be using #[repr(transparent)] to ensure that the compiler won't do something else :)
1 comments
codeflo 1281 days ago
Sure, it’s good to point out the difference between “the behavior of a typical optimizing compiler” and “things actually guaranteed by the language”. The context of the discussion was the former, I think. I’m not even that certain that monomorphization is actually required in theory.
link
estebank 1281 days ago
Yes, monomorphization isn't needed in theory, as long as the user-visible behavior remains the same, and in practice the team is exploring options[1] to identify cases where the currently manual practice of writing

    pub fn foo<T: AsRef<X>>(x: T) {
        inner_foo(x.as_ref());
    }
    fn inner_foo(_: &X) { todo!() }
can be instead done by the compiler automatically (turning monomorphized code back into polymorphic code, hence the polimorphization hame).

[1]: https://rustc-dev-guide.rust-lang.org/backend/monomorph.html...

link