Make Archetypes.archetype_component_count private (#10774)

Make more clear where it is used and how.

crates/bevy_ecs/src/archetype.rs

@@ -588,13 +588,6 @@ struct ArchetypeComponents {
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
 pub struct ArchetypeComponentId(usize);
 
-impl ArchetypeComponentId {
-    #[inline]
-    pub(crate) const fn new(index: usize) -> Self {
-        Self(index)
-    }
-}
-
 impl SparseSetIndex for ArchetypeComponentId {
     #[inline]
     fn sparse_set_index(&self) -> usize {
@@ -614,7 +607,7 @@ impl SparseSetIndex for ArchetypeComponentId {
 /// [module level documentation]: crate::archetype
 pub struct Archetypes {
     pub(crate) archetypes: Vec<Archetype>,
-    pub(crate) archetype_component_count: usize,
+    archetype_component_count: usize,
     by_components: bevy_utils::HashMap<ArchetypeComponents, ArchetypeId>,
 }
 
@@ -666,6 +659,22 @@ impl Archetypes {
         }
     }
 
+    /// Generate and store a new [`ArchetypeComponentId`].
+    ///
+    /// This simply increment the counter and return the new value.
+    ///
+    /// # Panics
+    ///
+    /// On archetype component id overflow.
+    pub(crate) fn new_archetype_component_id(&mut self) -> ArchetypeComponentId {
+        let id = ArchetypeComponentId(self.archetype_component_count);
+        self.archetype_component_count = self
+            .archetype_component_count
+            .checked_add(1)
+            .expect("archetype_component_count overflow");
+        id
+    }
+
     /// Fetches an immutable reference to an [`Archetype`] using its
     /// ID. Returns `None` if no corresponding archetype exists.
     #[inline]

crates/bevy_ecs/src/world/mod.rs

@@ -1780,13 +1780,11 @@ impl World {
         &mut self,
         component_id: ComponentId,
     ) -> &mut ResourceData<true> {
-        let archetype_component_count = &mut self.archetypes.archetype_component_count;
+        let archetypes = &mut self.archetypes;
         self.storages
             .resources
             .initialize_with(component_id, &self.components, || {
-                let id = ArchetypeComponentId::new(*archetype_component_count);
+                archetypes.new_archetype_component_id()
-                *archetype_component_count += 1;
-                id
             })
     }
 
@@ -1797,13 +1795,11 @@ impl World {
         &mut self,
         component_id: ComponentId,
     ) -> &mut ResourceData<false> {
-        let archetype_component_count = &mut self.archetypes.archetype_component_count;
+        let archetypes = &mut self.archetypes;
         self.storages
             .non_send_resources
             .initialize_with(component_id, &self.components, || {
-                let id = ArchetypeComponentId::new(*archetype_component_count);
+                archetypes.new_archetype_component_id()
-                *archetype_component_count += 1;
-                id
             })
     }