fix(plugin-legacy): prevent constant folding for import.meta.env.LEGACY

close #1999

Author: yyx990803

packages/playground/legacy/main.js

@@ -5,6 +5,13 @@ async function run() {
 
 run()
 
-document.getElementById('env').textContent = `is legacy: ${
-  import.meta.env.LEGACY
-}`
+let isLegacy
+
+// make sure that branching works despite esbuild's constant folding (#1999)
+if (import.meta.env.LEGACY) {
+  if (import.meta.env.LEGACY === true) isLegacy = true
+} else {
+  if (import.meta.env.LEGACY === false) isLegacy = false
+}
+
+document.getElementById('env').textContent = `is legacy: ${isLegacy}`

packages/plugin-legacy/index.js

@@ -189,7 +189,7 @@ function viteLegacyPlugin(options = {}) {
         }
 
         if (raw.includes(legacyEnvVarMarker)) {
-          const re = new RegExp(`"${legacyEnvVarMarker}"`, 'g')
+          const re = new RegExp(legacyEnvVarMarker, 'g')
           if (config.build.sourcemap) {
             const s = new MagicString(raw)
             let match
@@ -550,8 +550,8 @@ function replaceLegacyEnvBabelPlugin() {
   return ({ types: t }) => ({
     name: 'vite-replace-env-legacy',
     visitor: {
-      StringLiteral(path) {
-        if (path.node.value === legacyEnvVarMarker) {
+      Identifier(path) {
+        if (path.node.name === legacyEnvVarMarker) {
           path.replaceWith(t.booleanLiteral(true))
         }
       }

packages/plugin-legacy/package.json

@@ -32,6 +32,6 @@
     "systemjs": "^6.8.3"
   },
   "peerDependencies": {
-    "vite": "^2.0.0-beta.12"
+    "vite": "^2.0.0-beta.70"
   }
 }