fix(vite): use '' key for root scope in variable collector (#22679)

packages/vite/src/plugins/composable-keys.ts

@@ -141,14 +141,26 @@ export const composableKeysPlugin = createUnplugin((options: ComposableKeysOptio
   }
 })
 
+/*
+* track scopes with unique keys. for example
+* ```js
+* // root scope, marked as ''
+* function a () { // '0'
+*   function b () {} // '0-0'
+*   function c () {} // '0-1'
+* }
+* function d () {} // '1'
+* // ''
+* ```
+* */
 class ScopeTracker {
+  // the top of the stack is not a part of current key, it is used for next level
   scopeIndexStack: number[]
   curScopeKey: string
 
   constructor () {
-    // top level
     this.scopeIndexStack = [0]
-    this.curScopeKey = '0'
+    this.curScopeKey = ''
   }
 
   getKey () {
@@ -173,8 +185,7 @@ class ScopedVarsCollector {
 
   constructor () {
     this.all = new Map()
-    // top level
-    this.curScopeKey = '0'
+    this.curScopeKey = ''
   }
 
   refresh (scopeKey: string) {
@@ -192,7 +203,7 @@ class ScopedVarsCollector {
 
   hasVar (scopeKey: string, name: string) {
     const indices = scopeKey.split('-').map(Number)
-    for (let i = indices.length; i > 0; i--) {
+    for (let i = indices.length; i >= 0; i--) {
       if (this.all.get(indices.slice(0, i).join('-'))?.has(name)) {
         return true
       }

test/fixtures/basic/other-composables-folder/local.ts

@@ -0,0 +1,5 @@
+function useAsyncData (s?: any) { return s }
+
+export const ShouldNotBeKeyed = (() => {
+  return useAsyncData()
+})()

test/fixtures/basic/pages/keyed-composables/local.vue

@@ -1,4 +1,6 @@
 <script setup lang="ts">
+import { ShouldNotBeKeyed } from '~/other-composables-folder/local'
+
 function localScopedComposables () {
   const _assert = (key?: string) => key ?? 'was not keyed'
 
@@ -39,11 +41,15 @@ function localScopedComposables () {
     })()]
   }
 
+  function fromNonComponentFile () {
+    return [_assert(ShouldNotBeKeyed)]
+  }
+
   function useCustomKeyedComposable (arg?: string) {
     return _assert(arg)
   }
 
-  return [...basic(), ...hoisting(), ...complex(), ...deeperScope(), useCustomKeyedComposable()]
+  return [...basic(), ...hoisting(), ...complex(), ...deeperScope(), ...fromNonComponentFile(), useCustomKeyedComposable()]
 }
 const skippedLocalScopedComposables = localScopedComposables().every(res => res === 'was not keyed')
 </script>