Incorrect suggestion to add a semicolon in `if let` when trying to borrow a value more than once

[miDeb]

Given the following code: https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=ef9ffeffe1ceaef2201ebc972bfc11cd

use std::collections::BinaryHeap;

fn foo(heap: &mut BinaryHeap<i32>) {
    if let Some(value) = heap.peek_mut() {
        heap.pop();
    }
}

The current output is:

error[E0499]: cannot borrow `*heap` as mutable more than once at a time
 --> src/lib.rs:5:9
  |
4 |     if let Some(value) = heap.peek_mut() {
  |                          ---------------
  |                          |
  |                          first mutable borrow occurs here
  |                          a temporary with access to the first borrow is created here ...
5 |         heap.pop();
  |         ^^^^ second mutable borrow occurs here
6 |     }
7 | }
  | - ... and the first borrow might be used here, when that temporary is dropped and runs the destructor for type `Option<PeekMut<'_, i32>>`
  |
help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped
  |
6 |     };
  |      ^

Ideally the output should look like:
Without the "help" part, which is what it looks like when I actually add the semicolon (not sure if the rust compiler could also accept this code without an error)

[miDeb]

This also happens with a match, so feel free to change the title to something more appropriate.

[ForgottenGensym]

Just to clarify, this only happens when the first borrow is in the condition of the if let, and the second is in the body

[inquisitivecrystal]

@rustbot label +A-borrow-checker +D-incorrect-suggestion