refactor(apiWatch): remove redundant overload for readonly

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

@@ -15,9 +15,12 @@ import { expectType } from './utils'
 const source = ref('foo')
 const source2 = computed(() => source.value)
 const source3 = () => 1
-type Bar = Ref<string> | ComputedRef<string> | (() => number)
 
+type Bar = Ref<string> | ComputedRef<string> | (() => number)
 type Foo = readonly [Ref<string>, ComputedRef<string>, () => number]
+
+const readonlyArr: Foo = [source, source2, source3]
+
 // lazy watcher will have consistent types for oldValue.
 watch(source, (value, oldValue) => {
   expectType<string>(value)
@@ -44,6 +47,13 @@ watch(reactive([source, source2, source3]), value => {
 watch(reactive([source, source2, source3] as const), value => {
   expectType<Reactive<Foo>>(value)
 })
+
+// readonly array
+watch(readonlyArr, (values, oldValues) => {
+  expectType<Readonly<[string, string, number]>>(values)
+  expectType<Readonly<[string, string, number]>>(oldValues)
+})
+
 // immediate watcher's oldValue will be undefined on first run.
 watch(
   source,
@@ -92,6 +102,19 @@ watch(reactive([source, source2, source3] as const), (value, oldVals) => {
   expectType<Reactive<Foo>>(value)
   expectType<Reactive<Foo> | undefined>(oldVals)
 })
+
+// readonly array
+watch(
+  readonlyArr,
+  (values, oldValues) => {
+    expectType<Readonly<[string, string, number]>>(values)
+    expectType<
+      Readonly<[string | undefined, string | undefined, number | undefined]>
+    >(oldValues)
+  },
+  { immediate: true },
+)
+
 // should provide correct ref.value inner type to callbacks
 const nestedRefSource = ref({
   foo: ref(1),

packages/runtime-core/src/apiWatch.ts

@@ -142,18 +142,6 @@ export function watch<
   options?: WatchOptions<Immediate>,
 ): WatchStopHandle
 
-// overload: multiple sources w/ `as const`
-// watch([foo, bar] as const, () => {})
-// somehow [...T] breaks when the type is readonly
-export function watch<
-  T extends Readonly<MultiWatchSources>,
-  Immediate extends Readonly<boolean> = false,
->(
-  source: T,
-  cb: WatchCallback<MapSources<T, false>, MapSources<T, Immediate>>,
-  options?: WatchOptions<Immediate>,
-): WatchStopHandle
-
 // overload: watching reactive object w/ cb
 export function watch<
   T extends object,