fix

src/utils.rs

@@ -1,3 +1,6 @@
+#[cfg(feature = "alloc")]
+use alloc::vec::Vec;
+
 /// Like `a % b` but returns `b` instead of `0`.
 #[must_use]
 pub(crate) const fn rem_up(a: usize, b: usize) -> usize {
@@ -9,19 +12,23 @@ pub(crate) const fn rem_up(a: usize, b: usize) -> usize {
     }
 }
 
-fn last_idx<T: PartialEq>(x: &[T], value: &T) -> Option<usize> {
-    x.iter().rposition(|b| b != value)
+#[allow(dead_code)]
+#[inline]
+fn last_idx<T: PartialEq>(x: &[T], value: &T) -> usize {
+    x.iter().rposition(|b| b != value).map_or(0, |idx| idx + 1)
 }
 
+#[allow(dead_code)]
 #[must_use]
 #[inline]
 pub(crate) fn trim_end_slice<'a, T: PartialEq>(slice: &'a [T], value: &T) -> &'a [T] {
-    &slice[..last_idx(slice, value).unwrap_or(0)]
+    &slice[..last_idx(slice, value)]
 }
 
+#[cfg(feature = "alloc")]
 #[inline]
 pub(crate) fn trim_end_vec<T: PartialEq>(vec: &mut Vec<T>, value: &T) {
-    vec.truncate(last_idx(vec, value).map_or(0, |idx| idx + 1));
+    vec.truncate(last_idx(vec, value));
 }
 
 // Branch prediction hints.
@@ -52,3 +59,31 @@ pub(crate) const fn unlikely(b: bool) -> bool {
     }
     b
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_trim() {
+        assert_eq!(trim_end_slice(&[], &0), &[] as &[i32]);
+        assert_eq!(trim_end_slice(&[0], &0), &[] as &[i32]);
+        assert_eq!(trim_end_slice(&[0, 1], &0), &[0, 1]);
+        assert_eq!(trim_end_slice(&[0, 1, 0], &0), &[0, 1]);
+        assert_eq!(trim_end_slice(&[0, 1, 0, 0], &0), &[0, 1]);
+        assert_eq!(trim_end_slice(&[0, 1, 0, 0, 0], &0), &[0, 1]);
+        assert_eq!(trim_end_slice(&[0, 1, 0, 1, 0], &0), &[0, 1, 0, 1]);
+
+        let trim_end_vec = |mut v: Vec<i32>, x: &i32| {
+            trim_end_vec(&mut v, x);
+            v
+        };
+        assert_eq!(trim_end_vec(vec![], &0), &[] as &[i32]);
+        assert_eq!(trim_end_vec(vec![0], &0), &[] as &[i32]);
+        assert_eq!(trim_end_vec(vec![0, 1], &0), &[0, 1]);
+        assert_eq!(trim_end_vec(vec![0, 1, 0], &0), &[0, 1]);
+        assert_eq!(trim_end_vec(vec![0, 1, 0, 0], &0), &[0, 1]);
+        assert_eq!(trim_end_vec(vec![0, 1, 0, 0, 0], &0), &[0, 1]);
+        assert_eq!(trim_end_vec(vec![0, 1, 0, 1, 0], &0), &[0, 1, 0, 1]);
+    }
+}