Address MR 3756 review comments.

Cargo.lock

@@ -6720,6 +6720,7 @@ dependencies = [
  "fxhash",
  "hashbrown 0.12.3",
  "indexmap",
+ "itertools",
  "kiddo 0.1.7",
  "lazy_static",
  "num-derive",

common/Cargo.toml

@@ -29,6 +29,7 @@ serde = { version = "1.0.110", features = ["derive", "rc"] }
 vek = { version = "0.15.8", features = ["serde"] }
 chrono = "0.4.22"
 chrono-tz = "0.6"
+itertools = "0.10"
 sha2 = "0.10"
 serde_json = "1.0.50"
 

common/src/comp/buff.rs

@@ -3,6 +3,7 @@ use crate::uid::Uid;
 use core::{cmp::Ordering, time::Duration};
 #[cfg(not(target_arch = "wasm32"))]
 use hashbrown::HashMap;
+use itertools::Either;
 use serde::{Deserialize, Serialize};
 #[cfg(not(target_arch = "wasm32"))]
 use specs::{Component, DerefFlaggedStorage, VecStorage};
@@ -561,10 +562,9 @@ impl Buffs {
     pub fn iter_active(&self) -> impl Iterator<Item = &Buff> + '_ {
         self.kinds.iter().flat_map(move |(kind, ids)| {
             if kind.stacks() {
-                Box::new(ids.iter().filter_map(|id| self.buffs.get(id)))
-                    as Box<dyn Iterator<Item = &Buff>>
+                Either::Left(ids.iter().filter_map(|id| self.buffs.get(id)))
             } else {
-                Box::new(self.buffs.get(&ids[0]).into_iter())
+                Either::Right(self.buffs.get(&ids[0]).into_iter())
             }
         })
     }

common/systems/src/buff.rs

@@ -250,13 +250,7 @@ impl<'a> System<'a> for Sys {
                 .iter()
                 .map(|(kind, ids)| (*kind, ids.clone()))
                 .collect::<Vec<(BuffKind, Vec<BuffId>)>>();
-            buff_kinds.sort_by_key(|(kind, _)| {
-                if kind.affects_subsequent_buffs() {
-                    0
-                } else {
-                    1
-                }
-            });
+            buff_kinds.sort_by_key(|(kind, _)| !kind.affects_subsequent_buffs());
             for (buff_kind, buff_ids) in buff_kinds.into_iter() {
                 let mut active_buff_ids = Vec::new();
                 if buff_kind.stacks() {