From db5cbfd68849f9633f8c3d6c20143ba6a3cc81c6 Mon Sep 17 00:00:00 2001
From: Paula Gearon <gearon@gmail.com>
Date: Tue, 14 Oct 2025 08:14:44 -0400
Subject: [PATCH 1/2] CLJS-3454: New set instances are created when redundant
 data is added

---
 src/main/cljs/cljs/core.cljs      | 20 ++++++++++++++++----
 src/test/cljs/cljs/core_test.cljs | 21 +++++++++++++++++++++
 2 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/src/main/cljs/cljs/core.cljs b/src/main/cljs/cljs/core.cljs
index 27464f4f0..1e96c24f6 100644
--- a/src/main/cljs/cljs/core.cljs
+++ b/src/main/cljs/cljs/core.cljs
@@ -9304,7 +9304,10 @@ reduces them without incurring seq initialization"
 
   ICollection
   (-conj [coll o]
-    (PersistentHashSet. meta (assoc hash-map o nil) nil))
+    (let [m (-assoc hash-map o nil)]
+      (if (identical? m hash-map)
+        coll
+        (PersistentHashSet. meta m nil))))
 
   IEmptyableCollection
   (-empty [coll] (-with-meta (.-EMPTY PersistentHashSet) meta))
@@ -9341,7 +9344,10 @@ reduces them without incurring seq initialization"
 
   ISet
   (-disjoin [coll v]
-    (PersistentHashSet. meta (-dissoc hash-map v) nil))
+    (let [m (-dissoc hash-map v)]
+      (if (identical? m hash-map)
+        coll
+        (PersistentHashSet. meta m nil))))
 
   IFn
   (-invoke [coll k]
@@ -9459,7 +9465,10 @@ reduces them without incurring seq initialization"
 
   ICollection
   (-conj [coll o]
-    (PersistentTreeSet. meta (assoc tree-map o nil) nil))
+    (let [m (-assoc tree-map o nil)]
+      (if (identical? m tree-map)
+        coll
+        (PersistentTreeSet. meta m nil))))
 
   IEmptyableCollection
   (-empty [coll] (PersistentTreeSet. meta (-empty tree-map) 0))
@@ -9513,7 +9522,10 @@ reduces them without incurring seq initialization"
 
   ISet
   (-disjoin [coll v]
-    (PersistentTreeSet. meta (dissoc tree-map v) nil))
+    (let [m (-dissoc tree-map v)]
+      (if (identical? m tree-map)
+        coll
+        (PersistentTreeSet. meta m nil))))
 
   IFn
   (-invoke [coll k]
diff --git a/src/test/cljs/cljs/core_test.cljs b/src/test/cljs/cljs/core_test.cljs
index d92fb5105..9ce1a9976 100644
--- a/src/test/cljs/cljs/core_test.cljs
+++ b/src/test/cljs/cljs/core_test.cljs
@@ -737,6 +737,27 @@
   (is (= #{1 2} (hash-set 1 2 2)))
   (is (= #{1 2} (apply hash-set [1 2 2]))))
 
+(deftest test-ordered-set
+  (is (= #{1 2} (sorted-set 1 2 2)))
+  (is (= [1 2 3] (seq (sorted-set 2 3 1))))
+  (is (= #{1 2} (apply sorted-set [1 2 2]))))
+
+(deftest test-3454-conj
+  (is (= #{1 2 3} (conj #{1 2} 3)))
+  (is (= #{1 2 3} (conj (sorted-set 1 2) 3)))
+  (let [s #{1 2}
+        ss (sorted-set 1 2)]
+    (is (identical? s (conj s 2)))
+    (is (identical? ss (conj ss 2)))))
+
+(deftest test-3454-disj
+  (is (= #{1 2} (disj #{1 2 3} 3)))
+  (is (= #{1 2} (disj (sorted-set 1 2 3) 3)))
+  (let [s #{1 2}
+        ss (sorted-set 1 2)]
+    (is (identical? s (disj s 3)))
+    (is (identical? ss (disj ss 3)))))
+
 (deftest test-585
   (is (= (last (map identity (into [] (range 32)))) 31))
   (is (= (into #{} (range 32))

From 4eff03dd809120578326573e5de325dd67cc4885 Mon Sep 17 00:00:00 2001
From: davidnolen <david.nolen@gmail.com>
Date: Sun, 19 Oct 2025 11:41:10 -0400
Subject: [PATCH 2/2] add missing simple Set disjoin identical? check

---
 src/main/cljs/cljs/core.cljs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/main/cljs/cljs/core.cljs b/src/main/cljs/cljs/core.cljs
index d889a7ca9..82bd82c6b 100644
--- a/src/main/cljs/cljs/core.cljs
+++ b/src/main/cljs/cljs/core.cljs
@@ -13014,7 +13014,10 @@ reduces them without incurring seq initialization"
 
   ISet
   (-disjoin [coll v]
-    (Set. meta (-dissoc hash-map v) nil))
+    (let [new-hash-map (-dissoc hash-map v)]
+      (if (identical? new-hash-map hash-map)
+        coll
+        (Set. meta new-hash-map nil))))
 
   IEditableCollection
   (-as-transient [coll]