Cast struct object to dynamic trait object - struct

Question

This is a simpler version of my code:
type Res = Result<(), Box<dyn std::error::Error + Send + Sync>>;
// defined before-hand
pub trait Attr {
fn method(&self) -> Res;
}
// a struct, a block of code provided by user
// which is unknown by far
pub struct S;
// the trait implemented for provided struct
// user does this manually
// which is unknown by far
impl Attr for S {
fn method(&self) -> Res {
Ok(())
}
}
// in order to use the struct and its implemented method
// a possible way may be cast struct type to dynamic trait object
type Item = dyn Fn(&dyn Attr) -> Res;
pub fn use_method(f: &Item) {}
fn main() {
// casting happens here
// and do this job in macro, here is simplified version
let m = &(<S as Attr>::method) as &Item;
use_method(m);
}
It is required to tackle a struct, a block of code and its implementation both of which are unknown and provided by user. A rough direction may be using a trait as dynamic trait bounds which converted from struct object, but the compiler complain:
error[E0631]: type mismatch in function arguments
--> src/main.rs:30:13
|
4 | fn method(&self) -> Res;
| ------------------------ found signature of `for<'r> fn(&'r S) -> _`
...
30 | let m = &(<S as Attr>::method) as &Item;
| ^^^^^^^^^^^^^^^^^^^^^^ expected signature of `for<'r> fn(&'r (dyn Attr + 'r)) -> _`
|
= note: required for the cast to the object type `dyn for<'r> Fn(&'r (dyn Attr + 'r)) -> std::result::Result<(), Box<(dyn std::error::Error + Send + Sync + 'static)>>`
How can I get it done? Is there any other way?