# 警告：foo 1.0.0 不提供额外项 'devtools'

- **ID:** `python/pip-extras-unknown-extra`
- **领域:** python
- **类别:** install_error
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

请求了包元数据中未声明的额外项。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| 3.x | active | — | — |

## 解决方案

1. **** (90% 成功率)
   ```
   python -m pip show foo
pip install "foo[dev]"
   ```
2. **** (80% 成功率)
   ```
   pip install pytest black  # dependencies the extra would have pulled
   ```

## 无效尝试

- **** — The extra simply doesn't exist in metadata; forcing does not create it. (80% 失败率)
- **** — If 'all' extra is also undefined, same warning. (60% 失败率)