I have two implementation for removal function. Method 1 does not work because the compiler said curr is borrowed.

What is the difference between while let Some(boxed_node) = curr and match curr?

Method 1

    fn delete_method_1(&mut self, val : i32) {
        let mut curr = &mut self.head;

        while let Some(boxed_node) = curr {
            if boxed_node.val == val {
                *curr = boxed_node.next.take(); // it does not work
            } else {
                curr = &mut boxed_node.next
            }
        }
    }

Error message of Method1

while let Some(boxed_node) = curr {
   |                        ---------- `*curr` is borrowed here
26 |             if boxed_node.val == val {
27 |                 *curr = boxed_node.next.take(); // it does not work
   |                 ^^^^^
   |                 |
   |                 `*curr` is assigned to here but it was already borrowed
   |                 borrow later used here

Method 2

  fn delete_method_2(&mut self, val : i32) {
        let mut curr = &mut self.head;
        loop {
            match curr {
                None => return,
                Some(boxed_node) if boxed_node.val == val => {
                    *curr = boxed_node.next.take();
                },
                Some(boxed_node) => {
                    curr = &mut boxed_node.next;
                }
            }
        }
    }

I expected the Method 1 works.