unused_braces warning for default_value_t

[href]

Please complete the following tasks

• I have searched the discussions
• I have searched the existing issues

Rust Version

rustc 1.57.0 (f1edd0429 2021-11-29)

Clap Version

3.0.0

Minimal reproducible code

use clap::{ArgEnum, Parser, Subcommand};

#[derive(Parser)]
struct Cli {
    #[clap(subcommand)]
    command: Commands,
}

#[derive(Debug, ArgEnum, Clone)]
enum DisplayFormat {
    List,
}

impl Default for DisplayFormat {
    fn default() -> Self { DisplayFormat::List }
}

#[derive(Subcommand)]
enum Commands {
    Hosts {
        #[clap(short, long, arg_enum, default_value_t)]
        format: DisplayFormat,
    },
}

fn main() {
    let cli = Cli::parse();

    match &cli.command {
        Commands::Hosts { format } => {
            println!("Format: {:?}", format);
        }
    }
}

Steps to reproduce the bug with the above code

cargo check

Actual Behaviour

warning: unnecessary braces around method argument
  --> src/main.rs:21:39
   |
21 |         #[clap(short, long, arg_enum, default_value_t)]
   |                                       ^              ^
   |
   = note: `#[warn(unused_braces)]` on by default
help: remove these braces
   |
21 -         #[clap(short, long, arg_enum, default_value_t)]
21 +         #[clap(short, long, arg_enum, default_value_t)]
   |

warning: `hello` (bin "hello") generated 1 warning

Expected Behaviour

There should be no warning

Additional Context

Pretty inexperienced in Rust and new to Clap, so hopefully I'm not doing something wrong.

Debug Output

No response

[href]

Thank you! That was very quick 😌

[epage]

v3.0.1 is now released with the fix

[href]

I still seem to be getting the error with 3.0.1:

cargo check
    Checking clap v3.0.1
    Checking hello v0.1.0 (/Users/denis/Code/hello)
warning: unnecessary braces around method argument
  --> src/main.rs:21:39
   |
21 |         #[clap(short, long, arg_enum, default_value_t)]
   |                                       ^              ^
   |
   = note: `#[warn(unused_braces)]` on by default
help: remove these braces
   |
21 -         #[clap(short, long, arg_enum, default_value_t)]
21 +         #[clap(short, long, arg_enum, default_value_t)]
   |

warning: `hello` (bin "hello") generated 1 warning
    Finished dev [unoptimized + debuginfo] target(s) in 2.18s

Same code, just with 3.0.1 in Cargo.toml.

[epage]

Sorry, forgot to mark clap_derive for being released. It should be now.

[href]

Does this mean it will be fixed in 3.0.2, since I already have 3.0.1?

[epage]

It is fixed in clap_derive 3.0.1. Run cargo update -p clap_derive and you should have the fix.

[href]

That did it, thank you!