"Fill match arms" inside #[async_trait]-annotated impl fills incorrectly (extra closing brace, incorrect indentation)

[maddiemort]

rust-analyzer version: rust-analyzer 1.83.0 (90b35a62 2024-11-26)

rustc version: rustc 1.83.0 (90b35a623 2024-11-26)

editor or extension: Observed with both helix 25.1 (dabfb6ce) with the stock configuration, and nvim v0.10.3 both with rustaceanvim and with rust-analyzer directly configured through nvim-lspconfig. This doesn't appear to be sensitive to editor or extension version.

relevant settings: No settings appear to be relevant, this happens with multiple editors. Rust is installed through Rustup, and the editors are using the rust-analyzer binary installed via rustup component add rust-analyzer.

code snippet to reproduce:

# Cargo.toml

[package]
name = "match-arm-bug"
version = "0.1.0"
edition = "2021"

[dependencies]
async-trait = "0.1.85"

// lib.rs

#[async_trait::async_trait]
trait Bug {
    async fn foo(result: Result<(), ()>);
}

struct Buggy;

#[async_trait::async_trait]
impl Bug for Buggy {
    async fn foo(result: Result<(), ()>) {
        match result {}
    }
}

Go to the line containing match result {} and choose the "Fill match arms" code action. This produces the following output:

// lib.rs

#[async_trait::async_trait]
trait Bug {
    async fn foo(result: Result<(), ()>);
}

struct Buggy;

#[async_trait::async_trait]
impl Bug for Buggy {
    async fn foo(result: Result<(), ()>) {
        match result {
    Ok(_) => todo!(),
    Err(_) => todo!(),
}}
    }
}

[lnicola]

This was fixed in yesterday's release, but it didn't reach the rustup component.