structopt: error[E0277]: trait bound `String: From<&OsStr>`

Question

我正在使用 Rust 的 structopt crate，但是当我尝试编译示例时出现以下错误，

error[E0277]: the trait bound `String: From<&OsStr>` is not satisfied
   --> bin/seq.rs:21:36
    |
21  |     #[structopt(short, long, parse(from_os_str))]
    |                                    ^^^^^^^^^^^ the trait `From<&OsStr>` is not implemented for `String`
    |
    = help: the following implementations were found:
              <String as From<&String>>
              <String as From<&mut str>>
              <String as From<&str>>
              <String as From<Box<str>>>
            and 2 others
note: required by `from`

Answer 1

您可以将 String into a OsString 转换为绝对正确的转换，但不能将 OsString 转换为 String。

这是因为 OsStr 接受无效的东西 Strings 所以没有办法确保 structopt 解析成的 OsStr 可以转换为String.

您可能根本不需要 parse()，

#[structopt(short, long)]

没有

#[structopt(short, long, parse(from_os_str))]

structopt: error[E0277]: trait bound `String: From<&OsStr>`

structopt: error[E0277]: the trait bound `String: From<&OsStr>`

rust

structopt