fix(ssr): capture scope declaration correctly (#6281)

packages/vite/src/node/ssr/__tests__/ssrTransform.spec.ts

@@ -529,3 +529,64 @@ class A {
     "
   `)
 })
+
+test('delcare scope', async () => {
+  expect(
+    (
+      await ssrTransform(
+        `
+import { aaa, bbb, ccc, ddd } from 'vue'
+
+function foobar() {
+  ddd()
+
+  const aaa = () => {
+    bbb(ccc)
+    ddd()
+  }
+  const bbb = () => {
+    console.log('hi')
+  }
+  const ccc = 1
+  function ddd() {}
+
+  aaa()
+  bbb()
+  ccc()
+}
+
+aaa()
+bbb()
+`,
+        null,
+        null
+      )
+    ).code
+  ).toMatchInlineSnapshot(`
+    "
+    const __vite_ssr_import_0__ = await __vite_ssr_import__(\\"vue\\");
+
+
+    function foobar() {
+      ddd()
+
+      const aaa = () => {
+        bbb(ccc)
+        ddd()
+      }
+      const bbb = () => {
+        console.log('hi')
+      }
+      const ccc = 1
+      function ddd() {}
+
+      aaa()
+      bbb()
+      ccc()
+    }
+
+    __vite_ssr_import_0__.aaa()
+    __vite_ssr_import_0__.bbb()
+    "
+  `)
+})

packages/vite/src/node/ssr/ssrTransform.ts

@@ -180,7 +180,7 @@ export async function ssrTransform(
   // 3. convert references to import bindings & import.meta references
   walk(ast, {
     onIdentifier(id, parent, parentStack) {
-      const grandparent = parentStack[parentStack.length - 2]
+      const grandparent = parentStack[1]
       const binding = idToImportMap.get(id.name)
       if (!binding) {
         return
@@ -203,7 +203,7 @@ export async function ssrTransform(
         if (!declaredConst.has(id.name)) {
           declaredConst.add(id.name)
           // locate the top-most node containing the class declaration
-          const topNode = parentStack[1]
+          const topNode = parentStack[parentStack.length - 2]
           s.prependRight(topNode.start, `const ${id.name} = ${binding};\n`)
         }
       } else {
@@ -266,19 +266,14 @@ function walk(
   { onIdentifier, onImportMeta, onDynamicImport }: Visitors
 ) {
   const parentStack: Node[] = []
-  const scope: Record<string, number> = Object.create(null)
   const scopeMap = new WeakMap<_Node, Set<string>>()
+  const identifiers: [id: any, stack: Node[]][] = []
 
   const setScope = (node: FunctionNode, name: string) => {
     let scopeIds = scopeMap.get(node)
     if (scopeIds && scopeIds.has(name)) {
       return
     }
-    if (name in scope) {
-      scope[name]++
-    } else {
-      scope[name] = 1
-    }
     if (!scopeIds) {
       scopeIds = new Set()
       scopeMap.set(node, scopeIds)
@@ -286,13 +281,17 @@ function walk(
     scopeIds.add(name)
   }
 
+  function isInScope(name: string, parents: Node[]) {
+    return parents.some((node) => node && scopeMap.get(node)?.has(name))
+  }
+
   ;(eswalk as any)(root, {
     enter(node: Node, parent: Node | null) {
       if (node.type === 'ImportDeclaration') {
         return this.skip()
       }
 
-      parent && parentStack.push(parent)
+      parent && parentStack.unshift(parent)
 
       if (node.type === 'MetaProperty' && node.meta.name === 'import') {
         onImportMeta(node)
@@ -301,8 +300,12 @@ function walk(
       }
 
       if (node.type === 'Identifier') {
-        if (!scope[node.name] && isRefIdentifier(node, parent!, parentStack)) {
-          onIdentifier(node, parent!, parentStack)
+        if (
+          !isInScope(node.name, parentStack) &&
+          isRefIdentifier(node, parent!, parentStack)
+        ) {
+          // record the identifier, for DFS -> BFS
+          identifiers.push([node, parentStack.slice(0)])
         }
       } else if (isFunction(node)) {
         // If it is a function declaration, it could be shadowing an import
@@ -372,18 +375,15 @@ function walk(
     },
 
     leave(node: Node, parent: Node | null) {
-      parent && parentStack.pop()
-      const scopeIds = scopeMap.get(node)
-      if (scopeIds) {
-        scopeIds.forEach((id: string) => {
-          scope[id]--
-          if (scope[id] === 0) {
-            delete scope[id]
-          }
-        })
-      }
+      parent && parentStack.shift()
     }
   })
+
+  // emit the identifier events in BFS so the hoisted declarations
+  // can be captured correctly
+  identifiers.forEach(([node, stack]) => {
+    if (!isInScope(node.name, stack)) onIdentifier(node, stack[0], stack)
+  })
 }
 
 function isRefIdentifier(id: Identifier, parent: _Node, parentStack: _Node[]) {
@@ -459,12 +459,7 @@ function isFunction(node: _Node): node is FunctionNode {
 }
 
 function findParentFunction(parentStack: _Node[]): FunctionNode | undefined {
-  for (let i = parentStack.length - 1; i >= 0; i--) {
-    const node = parentStack[i]
-    if (isFunction(node)) {
-      return node
-    }
-  }
+  return parentStack.find((i) => isFunction(i)) as FunctionNode
 }
 
 function isInDestructuringAssignment(
@@ -475,15 +470,7 @@ function isInDestructuringAssignment(
     parent &&
     (parent.type === 'Property' || parent.type === 'ArrayPattern')
   ) {
-    let i = parentStack.length
-    while (i--) {
-      const p = parentStack[i]
-      if (p.type === 'AssignmentExpression') {
-        return true
-      } else if (p.type !== 'Property' && !p.type.endsWith('Pattern')) {
-        break
-      }
-    }
+    return parentStack.some((i) => i.type === 'AssignmentExpression')
   }
   return false
 }