fix(scan): avoid crawling type only import (#2810)

Co-authored-by: Anthony Fu <[email protected]>

Author: hannoeru

packages/playground/ssr-vue/dep-import-type/deep/index.d.ts

@@ -0,0 +1 @@
+export interface Foo {}

packages/playground/ssr-vue/dep-import-type/package.json

@@ -0,0 +1,5 @@
+{
+  "name": "dep-import-type",
+  "version": "0.0.0",
+  "main": "index.js"
+}

packages/playground/ssr-vue/package.json

@@ -20,6 +20,7 @@
     "@vitejs/plugin-vue-jsx": "^1.1.2",
     "@vue/compiler-sfc": "^3.0.8",
     "@vue/server-renderer": "^3.0.6",
+    "dep-import-type": "link:./dep-import-type",
     "compression": "^1.7.4",
     "cross-env": "^7.0.3",
     "express": "^4.17.1",

packages/playground/ssr-vue/src/components/ImportType.vue

@@ -0,0 +1,9 @@
+<template>
+  <p>import type should be removed without side-effect</p>
+</template>
+
+<script setup lang="ts">
+import type { Foo } from 'dep-import-type/deep'
+
+const msg: Foo = {}
+</script>

packages/playground/ssr-vue/src/pages/Home.vue

@@ -6,11 +6,14 @@
   <button @click="state.count++">count is: {{ state.count }}</button>
   <Foo />
   <p class="virtual">msg from virtual module: {{ foo.msg }}</p>
+
+  <ImportType/>
 </template>
 
 <script setup>
 import foo from '@foo'
 import { reactive, defineAsyncComponent } from 'vue'
+import ImportType from '../components/ImportType.vue'
 const Foo = defineAsyncComponent(() =>
   import('../components/Foo').then((mod) => mod.Foo)
 )

packages/vite/src/node/optimizer/scan.ts

@@ -38,7 +38,7 @@ const htmlTypesRE = /\.(html|vue|svelte)$/
 // use Acorn because it's slow. Luckily this doesn't have to be bullet proof
 // since even missed imports can be caught at runtime, and false positives will
 // simply be ignored.
-const importsRE = /\bimport(?:[\w*{}\n\r\t, ]+from\s*)?\s*("[^"]+"|'[^']+')/gm
+const importsRE = /\bimport(?!\s+type)(?:[\w*{}\n\r\t, ]+from\s*)?\s*("[^"]+"|'[^']+')/gm
 
 export async function scanImports(
   config: ResolvedConfig

yarn.lock

@@ -2652,6 +2652,10 @@ delegate@^3.1.2:
   version "0.0.0"
   uid ""
 
+"dep-import-type@link:./packages/playground/ssr-vue/dep-import-type":
+  version "0.0.0"
+  uid ""
+
 "dep-linked-include@link:./packages/playground/optimize-deps/dep-linked-include":
   version "0.0.0"
   uid ""