Rust 预期绑定生存期参数，在尝试传递选项时找到具体生存期

在下面的代码中，我试图向高阶函数invoke\u me\u传递一个选项。正在传递的函数如果存在将被调用，否则不会被调用

该选项是使用其他布尔特征方法中的as_-some构建的，复制到板条箱中

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我可能遗漏了一些显式的生命周期参数或类似的东西，但我无法理解。fn->>是否已经与for匹配？

使用闭包作为高阶函数很棘手。我注意到，显式地编写参数类型通常会有所帮助。在您的情况下：

问题似乎是invoke|me|可能接受一个具有很多可能性的泛型参数，而| t|{}可能意味着任何东西，编译器无法同时匹配这两个参数。在这种情况下，添加类型注释会有所帮助

我个人认为这是一个编译器错误，但我以前错了…

struct Thing{}

fn invoke_me_maybe<F: FnOnce(&mut Thing)>(t: &mut Thing, opt_f: Option<F>) {
    if let Some(f) = opt_f {
        f(t);
    }
}

trait BoolOption {
    fn as_some<T>(self, some: T) -> Option<T>;
}

impl BoolOption for bool {
    fn as_some<T>(self, some: T) -> Option<T> {
        if self { Some(some) } else { None }
    }
}

pub fn main() {
    let mut thing = Thing{};
    invoke_me_maybe(&mut thing, true.as_some(|t| {}));
}

error[E0631]: type mismatch in closure arguments
  --> src/main.rs:21:33
   |
3  | fn invoke_me_maybe<F: FnOnce(&mut Thing)>(t: &mut Thing, opt_f: Option<F>) {
   |    ---------------    ------------------ required by this bound in `invoke_me_maybe`
...
21 |     invoke_me_maybe(&mut thing, true.as_some(|t| {}));
   |                                 ^^^^^^^^^^^^^---^^^^
   |                                 |            |
   |                                 |            found signature of `fn(_) -> _`
   |                                 expected signature of `for<'r> fn(&'r mut Thing) -> _`

error[E0271]: type mismatch resolving `for<'r> <[closure@src/main.rs:21:46: 21:52] as std::ops::FnOnce<(&'r mut Thing,)>>::Output == ()`
  --> src/main.rs:21:5
   |
3  | fn invoke_me_maybe<F: FnOnce(&mut Thing)>(t: &mut Thing, opt_f: Option<F>) {
   |    ---------------    ------------------ required by this bound in `invoke_me_maybe`
...
21 |     invoke_me_maybe(&mut thing, true.as_some(|t| {}));
   |     ^^^^^^^^^^^^^^^ expected bound lifetime parameter, found concrete lifetime

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0271, E0631.
For more information about an error, try `rustc --explain E0271`.
error: could not compile `playground`.

To learn more, run the command again with --verbose.

    invoke_me_maybe(&mut thing, true.as_some(|t: &mut Thing| {}));