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Relax From<array> for SmallVec to allow different length arrays.
1 parent a0efe3c commit db63036

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2 files changed

+21
-3
lines changed

2 files changed

+21
-3
lines changed

src/lib.rs

+11-3
Original file line numberDiff line numberDiff line change
@@ -1909,9 +1909,17 @@ impl<'a, T: Clone, const N: usize> From<&'a [T]> for SmallVec<T, N> {
19091909
slice.iter().cloned().collect()
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}
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}
1912-
impl<T, const N: usize> From<[T; N]> for SmallVec<T, N> {
1913-
fn from(array: [T; N]) -> Self {
1914-
Self::from_buf(array)
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1913+
impl<T, const N: usize, const M: usize> From<[T; M]> for SmallVec<T, N> {
1914+
fn from(array: [T; M]) -> Self {
1915+
let mut this = Self::with_capacity(M);
1916+
let array = ManuallyDrop::new(array);
1917+
// SAFETY: M <= this.capacity()
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unsafe {
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copy_nonoverlapping(array.as_ptr(), this.as_mut_ptr(), M);
1920+
this.set_len(M);
1921+
}
1922+
this
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}
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}
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impl<T, const N: usize> From<Vec<T>> for SmallVec<T, N> {

src/tests.rs

+10
Original file line numberDiff line numberDiff line change
@@ -656,6 +656,16 @@ fn test_from() {
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let small_vec: SmallVec<NoClone, 1> = SmallVec::from(vec);
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assert_eq!(&*small_vec, &[NoClone(42)]);
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drop(small_vec);
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660+
let array = [1; 128];
661+
let small_vec: SmallVec<u8, 1> = SmallVec::from(array);
662+
assert_eq!(&*small_vec, vec![1; 128].as_slice());
663+
drop(small_vec);
664+
665+
let array = [99];
666+
let small_vec: SmallVec<u8, 128> = SmallVec::from(array);
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assert_eq!(&*small_vec, &[99u8]);
668+
drop(small_vec);
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}
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661671
#[test]

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