问题是您对value_name（仅用于CLI帮助选项）有一点误解，或者您忽略了参数名称区分大小写。
您有两个选项可让此作业如预期般运作：
1.使用YAML（change .rs）中指定的小写参数名称：
YAML：

...
args:
  - config:
      short: c
      long: config
      value_name: CONFIG
      help: Specifies the config file to use.
      takes_value: true
      default_value: "1"
  - verbose:
      short: v
      long: verbose
      value_name: VERBOSE
      help: Sets verbosity. 0 = silent, > 0 = verbose.
      takes_value: true
      default_value: "1"

rust eclipse ：

use clap::{load_yaml, App};

fn main() {
    let yaml = load_yaml!("cli.yml");
    let matches = App::from_yaml(yaml).get_matches();
    let verbosity =
    matches.value_of("verbose")
    .and_then(|s| s.parse::<u8>().ok())
    .unwrap();
    println!("{}", verbosity);
}

1.使用代码（change .yaml）中指定的大写名称：YAML：

...
args:
  - config:
      short: c
      long: config
      value_name: CONFIG
      help: Specifies the config file to use.
      takes_value: true
      default_value: "1"
  - VERBOSE:
      short: v
      long: verbose
      value_name: VERBOSE
      help: Sets verbosity. 0 = silent, > 0 = verbose.
      takes_value: true
      default_value: "1"

rust 色

use clap::{load_yaml, App};

fn main() {
    let yaml = load_yaml!("cli.yml");
    let matches = App::from_yaml(yaml).get_matches();
    let verbosity =
    matches.value_of("VERBOSE")
    .and_then(|s| s.parse::<u8>().ok())
    .unwrap();
    println!("{}", verbosity);
}