refactor(compiler): extract shared ast transform utils

Also improve referenced identifier check using isReferenced from  @babel/types

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

@@ -8,27 +8,29 @@ import {
   WritableComputedRef
 } from '@vue/reactivity'
 
-export function $ref<T>(arg: T | Ref<T>): UnwrapRef<T>
+declare const RefMarker: unique symbol
+type RefValue<T> = T & { [RefMarker]?: any }
+
+export function $ref<T>(arg?: T | Ref<T>): RefValue<UnwrapRef<T>>
 export function $ref() {}
 
-export function $shallowRef<T>(arg: T): T {
-  return arg
-}
+export function $shallowRef<T>(arg?: T): RefValue<T>
+export function $shallowRef() {}
 
 declare const ComputedRefMarker: unique symbol
-type ComputedValue<T> = T & { [ComputedRefMarker]?: any }
+type ComputedRefValue<T> = T & { [ComputedRefMarker]?: any }
 
 declare const WritableComputedRefMarker: unique symbol
-type WritableComputedValue<T> = T & { [WritableComputedRefMarker]?: any }
+type WritableComputedRefValue<T> = T & { [WritableComputedRefMarker]?: any }
 
 export function $computed<T>(
   getter: () => T,
   debuggerOptions?: DebuggerOptions
-): ComputedValue<T>
+): ComputedRefValue<T>
 export function $computed<T>(
   options: WritableComputedOptions<T>,
   debuggerOptions?: DebuggerOptions
-): WritableComputedValue<T>
+): WritableComputedRefValue<T>
 export function $computed() {}
 
 export function $fromRefs<T>(source: T): ShallowUnwrapRef<T>
@@ -36,9 +38,13 @@ export function $fromRefs() {
   return null as any
 }
 
-export function $raw<T>(value: ComputedValue<T>): ComputedRef<T>
-export function $raw<T>(value: WritableComputedValue<T>): WritableComputedRef<T>
-export function $raw<T>(value: T): Ref<T>
+export function $raw<T extends ComputedRefValue<any>>(
+  value: T
+): T extends ComputedRefValue<infer V> ? ComputedRef<V> : never
+export function $raw<T>(
+  value: WritableComputedRefValue<T>
+): WritableComputedRef<T>
+export function $raw<T>(value: RefValue<T>): Ref<T>
 export function $raw() {
   return null as any
 }