From fa6f51bb1b110cddc7dc41cb7e531fab27fe871f Mon Sep 17 00:00:00 2001
From: Taku Amano <taku@taaas.jp>
Date: Wed, 1 Jan 2025 13:34:26 +0900
Subject: [PATCH] fix(jsx/dom): should not return memoized result when context
 is changed (#3792)

---
 src/jsx/dom/index.test.tsx | 32 ++++++++++++++++++++++++++++++++
 src/jsx/dom/render.ts      | 14 +++++++++++++-
 2 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/src/jsx/dom/index.test.tsx b/src/jsx/dom/index.test.tsx
index 03e552fe8..23a4f82eb 100644
--- a/src/jsx/dom/index.test.tsx
+++ b/src/jsx/dom/index.test.tsx
@@ -19,6 +19,8 @@ import DefaultExport, {
   cloneElement,
   cloneElement as cloneElementForDom,
   createElement as createElementForDom,
+  createContext,
+  useContext,
   createPortal,
   flushSync,
   isValidElement,
@@ -1492,6 +1494,36 @@ describe('DOM', () => {
       expect(root.innerHTML).toBe('<div><div><p>Count: 1</p></div><button>+</button></div>')
       expect(renderCount).toBe(2)
     })
+
+    it('should not return memoized result when context is not changed', async () => {
+      const Context = createContext<[number, (arg: number | ((value: number) => number)) => void]>([
+        0,
+        () => {},
+      ])
+      const Container: FC<{ children: Child }> = ({ children }) => {
+        const [count, setCount] = useState(0)
+        return <Context.Provider value={[count, setCount]}>{children}</Context.Provider>
+      }
+      const Content = () => {
+        const [count, setCount] = useContext(Context)
+        return (
+          <>
+            <span>{count}</span>
+            <button onClick={() => setCount((c) => c + 1)}>+</button>
+          </>
+        )
+      }
+      const app = (
+        <Container>
+          <Content />
+        </Container>
+      )
+      render(app, root)
+      expect(root.innerHTML).toBe('<span>0</span><button>+</button>')
+      root.querySelector('button')?.click()
+      await Promise.resolve()
+      expect(root.innerHTML).toBe('<span>1</span><button>+</button>')
+    })
   })
 
   describe('useRef', async () => {
diff --git a/src/jsx/dom/render.ts b/src/jsx/dom/render.ts
index 2297c3af3..ecaaaa626 100644
--- a/src/jsx/dom/render.ts
+++ b/src/jsx/dom/render.ts
@@ -451,6 +451,16 @@ const applyNodeObject = (node: NodeObject, container: Container, isNew: boolean)
   }
 }
 
+const isSameContext = (
+  oldContexts: LocalJSXContexts,
+  newContexts: NonNullable<LocalJSXContexts>
+): boolean =>
+  !!(
+    oldContexts &&
+    oldContexts.length === newContexts.length &&
+    oldContexts.every((ctx, i) => ctx[1] === newContexts[i][1])
+  )
+
 const fallbackUpdateFnArrayMap: WeakMap<
   NodeObject,
   Array<() => Promise<NodeObject | undefined>>
@@ -525,13 +535,15 @@ export const build = (context: Context, node: NodeObject, children?: Child[]): v
             oldChild.props = child.props
             oldChild.f ||= child.f || node.f
             if (typeof child.tag === 'function') {
+              const oldContexts = oldChild[DOM_STASH][2]
               oldChild[DOM_STASH][2] = child[DOM_STASH][2] || []
               oldChild[DOM_STASH][3] = child[DOM_STASH][3]
 
               if (
                 !oldChild.f &&
                 ((oldChild.o || oldChild) === child.o || // The code generated by the react compiler is memoized under this condition.
-                  (oldChild.tag as MemorableFC<unknown>)[DOM_MEMO]?.(pP, oldChild.props)) // The `memo` function is memoized under this condition.
+                  (oldChild.tag as MemorableFC<unknown>)[DOM_MEMO]?.(pP, oldChild.props)) && // The `memo` function is memoized under this condition.
+                isSameContext(oldContexts, oldChild[DOM_STASH][2])
               ) {
                 oldChild.s = true
               }