Rollup merge of #95098 - shepmaster:vec-from-array-ref, r=dtolnay

impl From<&[T; N]> and From<&mut [T; N]> for Vec<T>

I really wanted to write:

```rust
fn example(a: impl Into<Vec<u8>>) {}

fn main() {
    example(b"raw");
}
```

library/alloc/src/vec/mod.rs

@@ -2933,6 +2933,48 @@ impl<T, const N: usize> From<[T; N]> for Vec<T> {
     }
 }
 
+#[cfg(not(no_global_oom_handling))]
+#[stable(feature = "vec_from_array_ref", since = "1.61.0")]
+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(b"raw"), vec![b'r', b'a', b'w']);
+    /// ```
+    #[cfg(not(test))]
+    fn from(s: &[T; N]) -> Vec<T> {
+        s.to_vec()
+    }
+
+    #[cfg(test)]
+    fn from(s: &[T; N]) -> Vec<T> {
+        crate::slice::to_vec(s, Global)
+    }
+}
+
+#[cfg(not(no_global_oom_handling))]
+#[stable(feature = "vec_from_array_ref", since = "1.61.0")]
+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]);
+    /// ```
+    #[cfg(not(test))]
+    fn from(s: &mut [T; N]) -> Vec<T> {
+        s.to_vec()
+    }
+
+    #[cfg(test)]
+    fn from(s: &mut [T; N]) -> Vec<T> {
+        crate::slice::to_vec(s, Global)
+    }
+}
+
 #[stable(feature = "vec_from_cow_slice", since = "1.14.0")]
 impl<'a, T> From<Cow<'a, [T]>> for Vec<T>
 where