feat(sfc): support $shallowRef ref sugar

packages/runtime-core/src/helpers/refSugar.ts

@@ -3,6 +3,10 @@ import { Ref, UnwrapRef, ShallowUnwrapRef, ComputedRef } from '@vue/reactivity'
 export function $ref<T>(arg: T | Ref<T>): UnwrapRef<T>
 export function $ref() {}
 
+export function $shallowRef<T>(arg: T): T {
+  return arg
+}
+
 declare const ComputedRefMarker: unique symbol
 type ComputedRefValue<T> = T & { [ComputedRefMarker]?: any }
 

packages/runtime-core/src/index.ts

@@ -354,4 +354,10 @@ export const compatUtils = (
 
 // Ref sugar macros ------------------------------------------------------------
 // for dts generation only
-export { $ref, $computed, $raw, $fromRefs } from './helpers/refSugar'
+export {
+  $ref,
+  $shallowRef,
+  $computed,
+  $raw,
+  $fromRefs
+} from './helpers/refSugar'

packages/runtime-core/types/scriptSetupHelpers.d.ts

@@ -6,6 +6,7 @@ type _defineExpose = typeof defineExpose
 type _withDefaults = typeof withDefaults
 
 type _ref = typeof $ref
+type _shallowRef = typeof $shallowRef
 type _computed = typeof $computed
 type _fromRefs = typeof $fromRefs
 type _raw = typeof $raw
@@ -17,6 +18,7 @@ declare global {
   const withDefaults: _withDefaults
 
   const $ref: _ref
+  const $shallowRef: _shallowRef
   const $computed: _computed
   const $fromRefs: _fromRefs
   const $raw: _raw