From a647436bf7d50e49e0354e5292f4b34a4d95f6da Mon Sep 17 00:00:00 2001
From: nogaten <32513694+nogaten@users.noreply.github.com>
Date: Mon, 15 Jul 2024 18:09:58 +0900
Subject: [PATCH 1/3] Add test

---
 tests/vanilla/store.test.tsx | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/tests/vanilla/store.test.tsx b/tests/vanilla/store.test.tsx
index 652a551ca4..1c9e6d212f 100644
--- a/tests/vanilla/store.test.tsx
+++ b/tests/vanilla/store.test.tsx
@@ -555,3 +555,20 @@ describe('aborting atoms', () => {
     expect(callAfterAbort).toHaveBeenCalledTimes(1)
   })
 })
+
+it('Unmount an atom that is no longer dependent within a derived atom (#2658)', async () => {
+  const condAtom = atom(true)
+
+  const baseAtom = atom(0)
+  const onUnmount = vi.fn()
+  baseAtom.onMount = () => onUnmount
+
+  const derivedAtom = atom((get) => {
+    if (get(condAtom)) get(baseAtom)
+  })
+
+  const store = createStore()
+  store.sub(derivedAtom, () => {})
+  store.set(condAtom, false)
+  expect(onUnmount).toHaveBeenCalledTimes(1)
+})

From 3fa5b7736eedaf3f7137160be07ad0c1c68aa6b0 Mon Sep 17 00:00:00 2001
From: nogaten <32513694+nogaten@users.noreply.github.com>
Date: Sat, 20 Jul 2024 22:48:56 +0900
Subject: [PATCH 2/3] fix #2658

---
 src/vanilla/store.ts | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/vanilla/store.ts b/src/vanilla/store.ts
index 49688c1c94..5e88fca29d 100644
--- a/src/vanilla/store.ts
+++ b/src/vanilla/store.ts
@@ -594,9 +594,9 @@ export const createStore = (): Store => {
       }
       for (const a of atomState.m.d || []) {
         if (!atomState.d.has(a)) {
+          atomState.m.d.delete(a)
           const aMounted = unmountAtom(pending, a)
           aMounted?.t.delete(atom)
-          atomState.m.d.delete(a)
         }
       }
     }
@@ -645,7 +645,9 @@ export const createStore = (): Store => {
     if (
       atomState.m &&
       !atomState.m.l.size &&
-      !Array.from(atomState.m.t).some((a) => getAtomState(a).m)
+      !Array.from(atomState.m.t).some(
+        (a) => getAtomState(a).m?.d.has(atom) ?? false,
+      )
     ) {
       // unmount self
       const onUnmount = atomState.m.u

From 738f51e553ac11404834e458a7f808ee8394dc2a Mon Sep 17 00:00:00 2001
From: daishi <daishi@axlight.com>
Date: Sun, 21 Jul 2024 09:00:47 +0900
Subject: [PATCH 3/3] refactor

---
 src/vanilla/store.ts | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/src/vanilla/store.ts b/src/vanilla/store.ts
index 5e88fca29d..8081c8ecc4 100644
--- a/src/vanilla/store.ts
+++ b/src/vanilla/store.ts
@@ -645,9 +645,7 @@ export const createStore = (): Store => {
     if (
       atomState.m &&
       !atomState.m.l.size &&
-      !Array.from(atomState.m.t).some(
-        (a) => getAtomState(a).m?.d.has(atom) ?? false,
-      )
+      !Array.from(atomState.m.t).some((a) => getAtomState(a).m?.d.has(atom))
     ) {
       // unmount self
       const onUnmount = atomState.m.u