Use all 64-bits of the Entity for a hash all the time.

Fixes PassHash only using Entity.index.

crates/bevy_ecs/src/entity/mod.rs

@@ -44,7 +44,7 @@ use crate::{
     storage::{SparseSetIndex, TableId, TableRow},
 };
 use serde::{Deserialize, Serialize};
-use std::{convert::TryFrom, fmt, mem, sync::atomic::Ordering};
+use std::{convert::TryFrom, fmt, hash::Hash, mem, sync::atomic::Ordering};
 
 #[cfg(target_has_atomic = "64")]
 use std::sync::atomic::AtomicI64 as AtomicIdCursor;
@@ -115,12 +115,18 @@ type IdCursor = isize;
 /// [`EntityCommands`]: crate::system::EntityCommands
 /// [`Query::get`]: crate::system::Query::get
 /// [`World`]: crate::world::World
-#[derive(Clone, Copy, Eq, Hash, Ord, PartialEq, PartialOrd)]
+#[derive(Clone, Copy, Eq, Ord, PartialEq, PartialOrd)]
 pub struct Entity {
     generation: u32,
     index: u32,
 }
 
+impl Hash for Entity {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        self.to_bits().hash(state);
+    }
+}
+
 pub(crate) enum AllocAtWithoutReplacement {
     Exists(EntityLocation),
     DidNotExist,

crates/bevy_utils/src/lib.rs

@@ -212,11 +212,6 @@ impl Hasher for PassHasher {
         panic!("can only hash u64 using PassHasher");
     }
 
-    #[inline]
-    fn write_u32(&mut self, i: u32) {
-        self.hash = i as u64;
-    }
-
     #[inline]
     fn write_u64(&mut self, i: u64) {
         self.hash = i;