From 4be1037f31e169d667059c44364fc3e43803accb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thorsten=20L=C3=BCnborg?= <t.luenborg@googlemail.com>
Date: Sun, 23 Jan 2022 14:08:27 +0100
Subject: [PATCH] fix(reactivity): ensure readonly refs can be replaced with
 new refs in reactive objects (#5310)

fix #5307
---
 packages/reactivity/__tests__/readonly.spec.ts | 13 ++++++++++++-
 packages/reactivity/src/baseHandlers.ts        |  2 +-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/packages/reactivity/__tests__/readonly.spec.ts b/packages/reactivity/__tests__/readonly.spec.ts
index 4462061b..73030c5b 100644
--- a/packages/reactivity/__tests__/readonly.spec.ts
+++ b/packages/reactivity/__tests__/readonly.spec.ts
@@ -476,7 +476,7 @@ describe('reactivity/readonly', () => {
     expect(isReadonly(rr.foo)).toBe(true)
   })
 
-  test('attemptingt to write to a readonly ref nested in a reactive object should fail', () => {
+  test('attemptingt to write plain value to a readonly ref nested in a reactive object should fail', () => {
     const r = ref(false)
     const ror = readonly(r)
     const obj = reactive({ ror })
@@ -486,4 +486,15 @@ describe('reactivity/readonly', () => {
 
     expect(obj.ror).toBe(false)
   })
+  test('replacing a readonly ref nested in a reactive object with a new ref', () => {
+    const r = ref(false)
+    const ror = readonly(r)
+    const obj = reactive({ ror })
+    try {
+      obj.ror = ref(true) as unknown as boolean
+    } catch (e) {}
+
+    expect(obj.ror).toBe(true)
+    expect(toRaw(obj).ror).not.toBe(ror) // ref successfully replaced
+  })
 })
diff --git a/packages/reactivity/src/baseHandlers.ts b/packages/reactivity/src/baseHandlers.ts
index eed9dc85..8ad8e571 100644
--- a/packages/reactivity/src/baseHandlers.ts
+++ b/packages/reactivity/src/baseHandlers.ts
@@ -150,7 +150,7 @@ function createSetter(shallow = false) {
     receiver: object
   ): boolean {
     let oldValue = (target as any)[key]
-    if (isReadonly(oldValue) && isRef(oldValue)) {
+    if (isReadonly(oldValue) && isRef(oldValue) && !isRef(value)) {
       return false
     }
     if (!shallow && !isReadonly(value)) {