Rustfmt: Implement field_init_shorthand feature

[MoSal]

#![feature(field_init_shorthand)]

struct AA{}
struct BB{}

struct CC {
    a: AA,
    b: BB
}

impl CC {
    fn new(a: AA, b: BB) -> Self {
        Self { a, b }
    }
}

cargo fmt error:

error: expected `:`, found `,`
  --> /tmp/foo/src/lib.rs:13:17
   |
13 |         Self { a, b }
   |                 ^

[bekh6ex]

The message is created in one of the following places:

• https://github.com/serde-rs/syntex/blob/master/syntex_syntax/src/parse/parser.rs#L446
• https://github.com/serde-rs/syntex/blob/master/syntex_syntax/src/parse/parser.rs#L733
• https://github.com/serde-rs/syntex/blob/master/syntex_syntax/src/parse/parser.rs#L3530

Should this issue be in this repository?
Probably it belongs to https://github.com/serde-rs/syntex

[matthew-piziak]

Weird. Looks like it doesn't error anymore on master. This works. Instead it just inserts the field names. I don't see the commit changing it though.

[clarfonthey]

Is there any progress on this?

[clarfonthey]

It appears that this works in the latest rustfmt, but it defaults to expanding out the shorthand. I think that the default should be to always use the shorthand when possible.

[nrc]

Fixed by https://github.com/rust-lang-nursery/rustfmt/commit/fad74c8ac9dcf9cd0f9db5439a30e5cadf5d6542