Why this rust FnMut closure code has lifetime errors?

Question

I want to make a closure hold &mut Vec, but these simple few lines of code can't compile.

I know this can be solved with RefCell, I just can't figure the error out.

struct Server<'a> {
    data: &'a mut Vec<i32>,
}

fn main() {
    let mut data = vec![1, 2, 3];
    let mut c = || {
         Server{
            data: &mut data,
        }
    };
    let server = c();
}

Rust playground link

The error message is:

error[E0495]: cannot infer an appropriate lifetime for borrow expression due to conflicting requirements
  --> src/main.rs:36:19
   |
36 |             data: &mut data,
   |                   ^^^^^^^^^
   |
note: first, the lifetime cannot outlive the lifetime '_ as defined on the body at 34:17...
  --> src/main.rs:34:17
   |
34 |     let mut c = || {
   |                 ^^
note: ...so that closure can access `data`
  --> src/main.rs:36:19
   |
36 |             data: &mut data,
   |                   ^^^^^^^^^
note: but, the lifetime must be valid for the call at 39:18...
  --> src/main.rs:39:18
   |
39 |     let server = c();
   |                  ^^^
note: ...so type `Server<'_>` of expression is valid during the expression
  --> src/main.rs:39:18
   |
39 |     let server = c();
   |                  ^^^

error: aborting due to previous error

Update:

I found this post answered the question, but I could not understand some parts of it:

It turns out that, returning &'a mut i32 is not feasible for the shorter-live invocation of call_mut. What we’ve really wanted for the return type of call_mut, was something like:

impl<'a> FnMut<(usize,)> for Closure<'a> {
    extern "rust-call"
    fn<'b> call_mut(&'b mut self, (i,): (usize, )) -> &'b mut i32 {
        self.inner.get_mut(i).unwrap()
    }
}

1. Why the call_mut fn has to use a 'b lifetime instead of 'a?
2. I found the code would work if change data: &mut Vec<i32> to data: &Vec<i32>, which makes me more confused that why lifetime is related to mut?