try0.rs

use std::ops::DerefMut;
use std::ops::Deref;

struct List<T> {
    car: Option<T>,
    cdr: Option<Box<List<T>>>,
}


fn main() {
    let mut a:List<i8> = List {car: None, cdr: None};
    {
        let mut tail = &mut a;
        for i in range(1, 42i8) {
            tail.cdr = Some(Box::new(List {car: Some(i), cdr: None}));
            tail = tail.cdr.unwrap().deref_mut();
        }
    }
}

// test.rs:16:20: 16:37 error: borrowed value does not live long enough
// test.rs:16             tail = tail.cdr.unwrap().deref_mut();
//                               ^~~~~~~~~~~~~~~~~
// test.rs:12:5: 18:6 note: reference must be valid for the block at 12:4...
// test.rs:12     {
// test.rs:13         let mut tail = &mut a;
// test.rs:14         for i in range(1, 42i8) {
// test.rs:15             tail.cdr = Some(Box::new(List {car: Some(i), cdr: None}));
// test.rs:16             tail = tail.cdr.unwrap().deref_mut();
// test.rs:17         }
//            ...
// test.rs:16:13: 16:50 note: ...but borrowed value is only valid for the statement at 16:12
// test.rs:16             tail = tail.cdr.unwrap().deref_mut();
//                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// test.rs:16:13: 16:50 help: consider using a `let` binding to increase its lifetime
// test.rs:16             tail = tail.cdr.unwrap().deref_mut();
//                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// test.rs:16:20: 16:24 error: cannot move out of borrowed content
// test.rs:16             tail = tail.cdr.unwrap().deref_mut();
//                               ^~~~
// error: aborting due to 2 previous errors

try1.rs

use std::ops::DerefMut;
use std::ops::Deref;

struct List<T> {
    car: Option<T>,
    cdr: Option<Box<List<T>>>,
}


fn main() {
    let mut a:List<i8> = List {car: None, cdr: None};
    {
        let mut tail = &mut a;
        let mut temp;
        for i in range(1, 42i8) {
            tail.cdr = Some(Box::new(List {car: Some(i), cdr: None}));
            temp = tail.cdr.unwrap();
            tail = temp.deref_mut();
        }
    }
}
// test.rs:17:20: 17:24 error: cannot move out of borrowed content
// test.rs:17             temp = tail.cdr.unwrap();
//                               ^~~~
// test.rs:17:13: 17:37 error: cannot assign to `temp` because it is borrowed
// test.rs:17             temp = tail.cdr.unwrap();
//                        ^~~~~~~~~~~~~~~~~~~~~~~~
// test.rs:18:20: 18:24 note: borrow of `temp` occurs here
// test.rs:18             tail = temp.deref_mut();
//                               ^~~~
// test.rs:18:20: 18:24 error: cannot borrow `temp` as mutable more than once at a time
// test.rs:18             tail = temp.deref_mut();
//                               ^~~~
// test.rs:18:20: 18:24 note: previous borrow of `temp` occurs here; the mutable borrow prevents subsequent moves, borrows, or modification of `temp` until the borrow ends
// test.rs:18             tail = temp.deref_mut();
//                               ^~~~
// test.rs:20:6: 20:6 note: previous borrow ends here
// test.rs:12     {
// ...
// test.rs:20     }
//                ^
// error: aborting due to 3 previous errors

try2.rs

use std::ops::DerefMut;
use std::ops::Deref;

struct List<T> {
    car: Option<T>,
    cdr: Option<Box<List<T>>>,
}


fn main() {
    let mut a:List<i8> = List {car: None, cdr: None};
    {
        let mut tail = &mut a;
        for i in range(1, 42i8) {
            let new = Box::new(List {car: Some(i), cdr: None});
            let next = new.deref_mut();
            tail.cdr = Some(new);
            tail = next;
        }
    }
}

// test.rs:16:24: 16:27 error: `new` does not live long enough
// test.rs:16             let next = new.deref_mut();
//                                   ^~~
// test.rs:12:5: 20:6 note: reference must be valid for the block at 12:4...
// test.rs:12     {
// test.rs:13         let mut tail = &mut a;
// test.rs:14         for i in range(1, 42i8) {
// test.rs:15             let new = Box::new(List {car: Some(i), cdr: None});
// test.rs:16             let next = new.deref_mut();
// test.rs:17             tail.cdr = Some(new);
//            ...
// test.rs:14:33: 19:10 note: ...but borrowed value is only valid for the block at 14:32
// test.rs:14         for i in range(1, 42i8) {
// test.rs:15             let new = Box::new(List {car: Some(i), cdr: None});
// test.rs:16             let next = new.deref_mut();
// test.rs:17             tail.cdr = Some(new);
// test.rs:18             tail = next;
// test.rs:19         }
// error: aborting due to previous error

try3.rs

use std::ops::DerefMut;
use std::ops::Deref;

struct List<T> {
    car: Option<T>,
    cdr: Option<Box<List<T>>>,
}


fn main() {
    let mut a:List<i8> = List {car: None, cdr: None};
    {
        let mut tail = &mut a;
        let mut temp: &mut List<i8>;
        for i in range(1, 42i8) {
            let new = Box::new(List {car: Some(i), cdr: None});
            let temp = new.deref_mut();
            tail.cdr = Some(new);
            tail = temp;
        }
    }
}

// test.rs:17:24: 17:27 error: `new` does not live long enough
// test.rs:17             let temp = new.deref_mut();
//                                   ^~~
// test.rs:12:5: 21:6 note: reference must be valid for the block at 12:4...
// test.rs:12     {
// test.rs:13         let mut tail = &mut a;
// test.rs:14         let mut temp: &mut List<i8>;
// test.rs:15         for i in range(1, 42i8) {
// test.rs:16             let new = Box::new(List {car: Some(i), cdr: None});
// test.rs:17             let temp = new.deref_mut();
//            ...
// test.rs:15:33: 20:10 note: ...but borrowed value is only valid for the block at 15:32
// test.rs:15         for i in range(1, 42i8) {
// test.rs:16             let new = Box::new(List {car: Some(i), cdr: None});
// test.rs:17             let temp = new.deref_mut();
// test.rs:18             tail.cdr = Some(new);
// test.rs:19             tail = temp;
// test.rs:20         }
// error: aborting due to previous error