Trait method parameters now need to have names in 2018 edition

Ryan1729 · 2018-12-07T06:40:11.532Z

The following compiles in the 2015 edition but not on the 2018 edition:

pub trait A {
    fn go(&self, u32);
}

If a name is added like so then it works on both editions:

pub trait A {
    fn go(&self, a: u32);
}

Playground link

Was this change intentional? I tried to find documentation or discussion of it, but was unable to.

scottmcm · 2018-12-07T06:50:19.182Z

github.com

rust-lang/rfcs/blob/master/text/1685-deprecate-anonymous-parameters.md

- Feature Name: deprecate_anonymous_parameters
- Start Date: 2016-07-19
- RFC PR: [rust-lang/rfcs#1685](https://github.com/rust-lang/rfcs/pull/1685)
- Rust Issue: [rust-lang/rust#41686](https://github.com/rust-lang/rust/issues/41686)

# Summary
[summary]: #summary

Currently Rust allows anonymous parameters in trait methods:

```Rust
trait T {
    fn foo(i32);

    fn bar_with_default_impl(String, String) {

    }
}
```

This file has been truncated. show original

Basically, this makes the rustdocs better, and makes it feasible to allow some things like slice patterns in method implementations in traits.

davidtwco · 2018-12-07T10:18:37.612Z

There’s an issue for this confusion from this change: #53990

system · 2019-03-25T08:31:16.577Z

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.