types(computed): allow computed getter and setter types to be unrelated

packages/dts-test/ref.test-d.ts

@@ -183,6 +183,26 @@ describe('allow getter and setter types to be unrelated', <T>() => {
   e.value = d
 })
 
+// computed
+describe('allow computed getter and setter types to be unrelated', () => {
+  const obj = ref({
+    name: 'foo',
+  })
+
+  const c = computed({
+    get() {
+      return JSON.stringify(obj.value)
+    },
+    set(val: typeof obj.value) {
+      obj.value = val
+    },
+  })
+
+  c.value = { name: 'bar' } // object
+
+  expectType<string>(c.value)
+})
+
 // shallowRef
 type Status = 'initial' | 'ready' | 'invalidating'
 const shallowStatus = shallowRef<Status>('initial')

packages/reactivity/src/computed.ts

@@ -20,7 +20,7 @@ export interface ComputedRef<T = any> extends WritableComputedRef<T> {
   [ComputedRefSymbol]: true
 }
 
-export interface WritableComputedRef<T> extends Ref<T> {
+export interface WritableComputedRef<T, S = T> extends Ref<T, S> {
   /**
    * @deprecated computed no longer uses effect
    */
@@ -30,9 +30,9 @@ export interface WritableComputedRef<T> extends Ref<T> {
 export type ComputedGetter<T> = (oldValue?: T) => T
 export type ComputedSetter<T> = (newValue: T) => void
 
-export interface WritableComputedOptions<T> {
+export interface WritableComputedOptions<T, S = T> {
   get: ComputedGetter<T>
-  set: ComputedSetter<T>
+  set: ComputedSetter<S>
 }
 
 /**
@@ -175,10 +175,10 @@ export function computed<T>(
   getter: ComputedGetter<T>,
   debugOptions?: DebuggerOptions,
 ): ComputedRef<T>
-export function computed<T>(
-  options: WritableComputedOptions<T>,
+export function computed<T, S = T>(
+  options: WritableComputedOptions<T, S>,
   debugOptions?: DebuggerOptions,
-): WritableComputedRef<T>
+): WritableComputedRef<T, S>
 export function computed<T>(
   getterOrOptions: ComputedGetter<T> | WritableComputedOptions<T>,
   debugOptions?: DebuggerOptions,