Remove needless Clone bounds on Box/Vec conversions (#209)

This changes the `TryFrom` impls for `Array` which convert from an owned
boxed slice or `Vec` into an `Array` to not require `Clone` bounds,
because we can move the owned data into the array.

Also adds tests.

Author: tarcieri

src/lib.rs

@@ -996,14 +996,14 @@ where
 #[cfg(feature = "alloc")]
 impl<T, U> TryFrom<alloc::boxed::Box<[T]>> for Array<T, U>
 where
-    Self: Clone,
     U: ArraySize,
 {
     type Error = TryFromSliceError;
 
     #[inline]
     fn try_from(b: alloc::boxed::Box<[T]>) -> Result<Self, TryFromSliceError> {
-        Self::try_from(&*b)
+        check_slice_length::<T, U>(b.as_ref())?;
+        Ok(Array::from_iter(b))
     }
 }
 
@@ -1024,14 +1024,14 @@ where
 #[cfg(feature = "alloc")]
 impl<T, U> TryFrom<alloc::vec::Vec<T>> for Array<T, U>
 where
-    Self: Clone,
     U: ArraySize,
 {
     type Error = TryFromSliceError;
 
     #[inline]
     fn try_from(v: alloc::vec::Vec<T>) -> Result<Self, TryFromSliceError> {
-        Self::try_from(v.as_slice())
+        check_slice_length::<T, U>(v.as_ref())?;
+        Ok(Array::from_iter(v))
     }
 }
 

tests/mod.rs

@@ -455,6 +455,23 @@ mod allocating {
     use super::*;
     use typenum::U4;
 
+    #[test]
+    fn array_try_from_boxed_slice() {
+        type A = Array<u8, U2>;
+        assert!(A::try_from(vec![1].into_boxed_slice()).is_err());
+        assert_eq!(
+            &A::try_from(vec![1, 2].into_boxed_slice()).unwrap(),
+            &[1, 2]
+        );
+    }
+
+    #[test]
+    fn array_try_from_vec() {
+        type A = Array<u8, U2>;
+        assert!(A::try_from(vec![1]).is_err());
+        assert_eq!(&A::try_from(vec![1, 2]).unwrap(), &[1, 2]);
+    }
+
     #[test]
     fn boxed_slice_from_array() {
         let array: Array<u8, U4> = Array([1, 2, 3, 4]);