fn DisjointMutArcSlice::from_iter: Use inline const {} block to r…

…emove warning about dummy type.

src/disjoint_mut.rs

@@ -1195,9 +1195,11 @@ impl<T> FromIterator<T> for DisjointMutArcSlice<T> {
             let arc_slice = iter.into_iter().collect::<Arc<[_]>>();
 
             // Do our best to check that `DisjointMut` is in fact `#[repr(transparent)]`.
-            type A = Vec<u8>; // Some concrete sized type.
-            const _: () = assert!(mem::size_of::<DisjointMut<A>>() == mem::size_of::<A>());
-            const _: () = assert!(mem::align_of::<DisjointMut<A>>() == mem::align_of::<A>());
+            const {
+                type A = Vec<u8>; // Some concrete sized type.
+                assert!(mem::size_of::<DisjointMut<A>>() == mem::size_of::<A>());
+                assert!(mem::align_of::<DisjointMut<A>>() == mem::align_of::<A>());
+            }
 
             // SAFETY: When `#[cfg(not(debug_assertions))]`, `DisjointMut` is `#[repr(transparent)]`,
             // containing only an `UnsafeCell`, which is also `#[repr(transparent)]`.