Mark Slot trait as unsafe

src/input.rs

@@ -290,7 +290,8 @@ pub trait HasBuilder {
     type Builder;
 }
 
-impl<C> Slot for Value<C>
+// SAFETY: `Value<C>` is our private type branded over the unique configuration `C`.
+unsafe impl<C> Slot for Value<C>
 where
     C: Configuration,
 {

src/interned.rs

@@ -843,7 +843,8 @@ where
     }
 }
 
-impl<C> Slot for Value<C>
+// SAFETY: `Value<C>` is our private type branded over the unique configuration `C`.
+unsafe impl<C> Slot for Value<C>
 where
     C: Configuration,
 {

src/table.rs

@@ -30,7 +30,11 @@ pub struct Table {
     non_full_pages: Mutex<FxHashMap<IngredientIndex, Vec<PageIndex>>>,
 }
 
-pub(crate) trait Slot: Any + Send + Sync {
+/// # Safety
+///
+/// Implementors of this trait need to make sure that their type is unique with respect to
+/// their owning ingredient as the allocation strategy relies on this.
+pub(crate) unsafe trait Slot: Any + Send + Sync {
     /// Access the [`MemoTable`][] for this slot.
     ///
     /// # Safety condition

src/tracked_struct.rs

@@ -912,7 +912,8 @@ where
     }
 }
 
-impl<C> Slot for Value<C>
+// SAFETY: `Value<C>` is our private type branded over the unique configuration `C`.
+unsafe impl<C> Slot for Value<C>
 where
     C: Configuration,
 {