Auto merge of #111278 - EFanZh:implement-from-array-refs-for-vec, r=dtolnay

Implement `From<{&,&mut} [T; N]>` for `Vec<T>` where `T: Clone`

Currently, if `T` implements `Clone`, we can create a `Vec<T>` from an `&[T]` or an `&mut [T]`, can we also support creating a `Vec<T>` from an `&[T; N]` or an `&mut [T; N]`? Also, do I need to add `#[inline]` to the implementation?

ACP: rust-lang/libs-team#220. [Accepted]

Closes #100880.

library/alloc/src/vec/mod.rs

@@ -3154,6 +3154,36 @@ impl<T: Clone> From<&mut [T]> for Vec<T> {
     }
 }
 
+#[cfg(not(no_global_oom_handling))]
+#[stable(feature = "vec_from_array_ref", since = "CURRENT_RUSTC_VERSION")]
+impl<T: Clone, const N: usize> From<&[T; N]> for Vec<T> {
+    /// Allocate a `Vec<T>` and fill it by cloning `s`'s items.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// assert_eq!(Vec::from(&[1, 2, 3]), vec![1, 2, 3]);
+    /// ```
+    fn from(s: &[T; N]) -> Vec<T> {
+        Self::from(s.as_slice())
+    }
+}
+
+#[cfg(not(no_global_oom_handling))]
+#[stable(feature = "vec_from_array_ref", since = "CURRENT_RUSTC_VERSION")]
+impl<T: Clone, const N: usize> From<&mut [T; N]> for Vec<T> {
+    /// Allocate a `Vec<T>` and fill it by cloning `s`'s items.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// assert_eq!(Vec::from(&mut [1, 2, 3]), vec![1, 2, 3]);
+    /// ```
+    fn from(s: &mut [T; N]) -> Vec<T> {
+        Self::from(s.as_mut_slice())
+    }
+}
+
 #[cfg(not(no_global_oom_handling))]
 #[stable(feature = "vec_from_array", since = "1.44.0")]
 impl<T, const N: usize> From<[T; N]> for Vec<T> {

library/alloc/tests/vec.rs

@@ -2562,3 +2562,13 @@ fn test_box_zero_allocator() {
     // Ensure all ZSTs have been freed.
     assert!(alloc.state.borrow().0.is_empty());
 }
+
+#[test]
+fn test_vec_from_array_ref() {
+    assert_eq!(Vec::from(&[1, 2, 3]), vec![1, 2, 3]);
+}
+
+#[test]
+fn test_vec_from_array_mut_ref() {
+    assert_eq!(Vec::from(&mut [1, 2, 3]), vec![1, 2, 3]);
+}