slice.unique returns incorrect slice

[kavalee]

Context

odin version dev-2024-03
Odin: dev-2024-03
OS: Arch Linux, Linux 6.7.8-arch1-1
CPU: Intel(R) Core(TM) i5-4590 CPU @ 3.30GHz
RAM: 15943 MiB

Expected Behavior

The slice returned from unique should be of length 1 for a slice of consecutive values.

Current Behavior

import "core:fmt"
import "core:slice"
main :: proc() {
	s := []int{2,2,2}
	res := slice.unique(s)
	fmt.println(res) // output: [2, 2, 2]
}

Suspicious code

// 'unique' replaces consecutive runs of equal elements with a single copy.
// The procedures modifies the slice in-place and returns the modified slice.
@(require_results)
unique :: proc(s: $S/[]$T) -> S where intrinsics.type_is_comparable(T) #no_bounds_check {
	if len(s) < 2 {
		return s
	}
	i := 1
	for j in 1..<len(s) {
		if s[j] != s[j-1] && i != j {
			s[i] = s[j]
		}
		i += 1
	}

	return s[:i]
}

i is always going to be len(s) since i is incremented every iteration of the loop, and the loop always runs len(s)-1 times.