examples, tests: prepare to enable other lints related to safety comments

Signed-off-by: Paolo Bonzini <[email protected]>

Author: bonzini

examples/linked_list.rs

@@ -92,6 +92,12 @@ impl PinnedDrop for ListHead {
 struct Link(Cell<NonNull<ListHead>>);
 
 impl Link {
+    /// # Safety
+    ///
+    /// The contents of the pointer should form a consistent circular
+    /// linked list; for example, a "next" link should be pointed back
+    /// by the target `ListHead`'s "prev" link and a "prev" link should be
+    /// pointed back by the target `ListHead`'s "next" link.
     #[inline]
     unsafe fn new_unchecked(ptr: NonNull<ListHead>) -> Self {
         Self(Cell::new(ptr))

tests/ring_buf.rs

@@ -65,7 +65,7 @@ impl<T, const SIZE: usize> RingBuffer<T, SIZE> {
         // SAFETY: We do not move `this`.
         let this = unsafe { self.get_unchecked_mut() };
         let next_head = unsafe { this.advance(this.head) };
-        // SAFETY: `head` and `tail` point into the same buffer.
+        // `head` and `tail` point into the same buffer.
         if ptr::eq(next_head, this.tail) {
             // We cannot advance `head`, since `next_head` would point to the same slot as `tail`,
             // which is currently live.
@@ -105,6 +105,9 @@ impl<T, const SIZE: usize> RingBuffer<T, SIZE> {
         Some(unsafe { init_from_closure(remove_init) })
     }
 
+    /// # Safety
+    ///
+    /// TODO
     unsafe fn advance(&mut self, ptr: *mut T) -> *mut T {
         let ptr = ptr.add(1);
         let origin: *mut _ = addr_of_mut!(self.buffer);