Hi, by curiosity, we can't export a copy of a substring from a string defined inside a block. We get an error that explain that string doesn't live outside the block, but we just want a copy part of that string.
How could we export a copy of a slice of local/inside string to make it available outside the block ?
I already found workarounds.correction by using the heap (by string, not &str), or by defining variables outside and before the block.

// Test : export slice from a string inside a block
fn main () {
    let mut version : & str = "0.0.0"; // default value
    // let mut line = String::new(); // it works if "line" is already existant outside the block
    
    for _i in [1..=2] { // some loop because of treatment
        // build local(inside the block) string "line" from some function or whatever. Here it is just a given example.
        let line = String::from(":v 1.2.3\r"); // or ":v1.2.3\r" (without space)
        // line = String::from(":v 1.2.3\r"); // or ":v1.2.3\r" (without space) <-- it works (because defined outside and will still exists after the block)
        
        // exctract "version" from "line" : = line(2..)
        // ======= ERROR HERE ==========
        // error[E0597]: `line` does not live long enough
        // I would like to copy the part "1.2.3" from ":v 1.2.3"
        version = line.get(2..).unwrap_or("").trim();
       
    }; // line has ended here
    
   println!("{}", version);
    
}

(Playground)

Errors:

   Compiling playground v0.0.1 (/playground)
error[E0597]: `line` does not live long enough
  --> src/main.rs:15:19
   |
 8 |         let line = String::from(":v 1.2.3\r"); // or ":v1.2.3\r" (without space)
   |             ---- binding `line` declared here
...
15 |         version = line.get(2..).unwrap_or("").trim();
   |                   ^^^^ borrowed value does not live long enough
16 |        
17 |     }; // line has ended here
   |     - `line` dropped here while still borrowed
18 |     
19 |    println!("{}", version);
   |                   ------- borrow later used here

For more information about this error, try `rustc --explain E0597`.
error: could not compile `playground` (bin "playground") due to 1 previous error

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