out_of_bounds_indexing false positive

This comes from a code reduction, so it's reasonable in its original context:

#![allow(unused_variables)]
fn main() {
    const N: usize = 1_000;
    let data = [0, 0, 0, 0];
    if N <= 4 {
        let result = data[N - 1];
    }
}

error: index out of bounds: the len is 4 but the index is 999
 --> src/main.rs:6:22
  |
6 |         let result = data[N - 1];
  |                      ^^^^^^^^^^^
  |
  = note: #[deny(const_err)] on by default

Reproduce the Rust snippet in src/main.rs using the Rust nightly setup referenced in the issue, then trace the out_of_bounds_indexing diagnostic. Done means the guarded access in the example no longer produces the reported false-positive error, with regression coverage for this case.