How can I repeatedly borrow the variable outside the closure in different closures in Rust?

This is the core codes, which return the type of Vec<(&'a str, i32)>
When I run this code,

let mut i = 0;
contents.lines().filter(|x| {
    i += 1;
    x.to_lowercase().contains(&query.to_lowercase())
}).map(|x|
    (x, i)
).collect()

it alerts that:

contents.lines().filter(|x| {
   |                             --- mutable borrow occurs here
56 |         i += 1;
   |         - first borrow occurs due to use of `i` in closure
57 |         x.to_lowercase().contains(&query.to_lowercase())
58 |     }).map(|x|
   |        --- ^^^ immutable borrow occurs here
   |        |
   |        mutable borrow later used by call
59 |         (x, i)
   |             - second borrow occurs due to use of `i` in closure

So how can I correct this code?

>Solution :

The best way to fix this code is to realize that what you’re doing is essentially enumerate() with index starting from 1 instead of zero, so either:

contents.lines().enumerate().filter(|(_, x)| {
    x.to_lowercase().contains(&query.to_lowercase())
}).map(|(i, x)|
    (x, i + 1)
).collect()

Or:

contents.lines().zip(1..).filter(|(x, _)| {
    x.to_lowercase().contains(&query.to_lowercase())
}).collect()