Proc-macro derive produced unparseable tokens

[xa888s]

This is the code I am using (full link):

#[derive(FromArgs, PartialEq, Debug)]
#[argh(
    description = "used to search for crackmes (WARNING: Only gets first page of results)",
    subcommand,
    name = "search"
)]
pub struct SearchArgs {
    #[argh(
        description = "the range of difficulty (i.e. 1..6)",
        from_str_fn(range_parser),
        option,
        default = "(1, 6)"
    )]
    pub difficulty: (u8, u8),

    #[argh(
        description = "the range of quality (i.e. 1..6)",
        from_str_fn(range_parser),
        option,
        default = "(1, 6)"
    )]
    pub quality: (u8, u8),

    #[argh(description = "name of crackme", option, default = "")]
    pub name: String,

    #[argh(description = "name of crackme's author", option, default = "")]
    pub author: String,

    #[argh(description = "language of crackme", option)]
    pub language: Option<Language>,

    #[argh(description = "platform of crackme", option)]
    pub platform: Option<Platform>,
}

Errors:

error: expected expression, found `)`
  --> src/cli.rs:18:10
   |
18 | #[derive(FromArgs, PartialEq, Debug)]
   |          ^^^^^^^^
   |          |
   |          expected expression
   |          while parsing this struct
   |
   = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)

error: proc-macro derive produced unparseable tokens
  --> src/cli.rs:18:10
   |
18 | #[derive(FromArgs, PartialEq, Debug)]
   |          ^^^^^^^^