sparse_set: drop fast_compact, expect full clear

TODO

@@ -20,7 +20,6 @@ TODO (high prio):
 * doc: exclude only views, storage entity, bump entities
 * deprecate/remove registry reserve, capacity, empty, data, destroyed, release and so on
 * test exclude-only views
-* drop fast_compact, make clear do clear for real :)
 
 WIP:
 * get rid of observers, storage based views made them pointless - document alternatives

src/entt/entity/sparse_set.hpp

@@ -274,13 +274,6 @@ protected:
         packed[static_cast<size_type>(entt)] = std::exchange(free_list, traits_type::combine(entt, tombstone));
     }
 
-    /*! @brief Compact function for empty sparse sets. */
-    void fast_compact() {
-        ENTT_ASSERT((compact(), size()) == 0u, "Non-empty set");
-        packed.clear();
-        free_list = tombstone;
-    }
-
 protected:
     /**
      * @brief Erases entities from a sparse set.
@@ -993,6 +986,10 @@ public:
     /*! @brief Clears a sparse set. */
     void clear() {
         pop_all();
+        // sanity check to avoid subtle issues due to storage classes
+        ENTT_ASSERT((compact(), size()) == 0u, "Non-empty set");
+        free_list = tombstone;
+        packed.clear();
     }
 
     /**

src/entt/entity/storage.hpp

@@ -367,10 +367,6 @@ protected:
                 std::destroy_at(std::addressof(element_at(static_cast<size_type>(first.index()))));
             }
         }
-
-        if constexpr(traits_type::in_place_delete) {
-            base_type::fast_compact();
-        }
     }
 
     /**