fix env reloading for turbopack

packages/next-env/index.ts

@@ -93,6 +93,12 @@ export function processEnv(
   return Object.assign(process.env, parsed)
 }
 
+export function resetEnv() {
+  if (initialEnv) {
+    replaceProcessEnv(initialEnv)
+  }
+}
+
 export function loadEnvConfig(
   dir: string,
   dev?: boolean,

packages/next/src/cli/next-dev.ts

@@ -23,6 +23,7 @@ import { getNpxCommand } from '../lib/helpers/get-npx-command'
 import Watchpack from 'watchpack'
 import stripAnsi from 'next/dist/compiled/strip-ansi'
 import { getPossibleInstrumentationHookFilenames } from '../build/worker'
+import { resetEnv } from '@next/env'
 
 let dir: string
 let isTurboSession = false
@@ -293,6 +294,9 @@ const nextDev: CliCommand = async (argv) => {
       }
     }
 
+    // Turbopack need to be in control over reading the .env files and watching them.
+    // So we need to start with a initial env to know which env vars are coming from the user.
+    resetEnv()
     let bindings: any = await loadBindings()
     let server = bindings.turbo.startDev({
       ...devServerOptions,

test/development/app-hmr/hmr.test.ts

@@ -8,7 +8,7 @@ createNextDescribe(
   {
     files: __dirname,
   },
-  ({ next, isTurbopack }) => {
+  ({ next }) => {
     describe('filesystem changes', () => {
       it('should not break when renaming a folder', async () => {
         const browser = await next.browser('/folder')
@@ -35,39 +35,37 @@ createNextDescribe(
         }
       })
 
-      if (!isTurbopack) {
-        it('should update server components pages when env files is changed (nodejs)', async () => {
-          const envContent = await next.readFile(envFile)
-          const browser = await next.browser('/env/node')
-          expect(await browser.elementByCss('p').text()).toBe('mac')
-          await next.patchFile(envFile, 'MY_DEVICE="ipad"')
+      it('should update server components pages when env files is changed (nodejs)', async () => {
+        const envContent = await next.readFile(envFile)
+        const browser = await next.browser('/env/node')
+        expect(await browser.elementByCss('p').text()).toBe('mac')
+        await next.patchFile(envFile, 'MY_DEVICE="ipad"')
 
-          try {
-            await check(async () => {
-              expect(await browser.elementByCss('p').text()).toBe('ipad')
-              return 'success'
-            }, /success/)
-          } finally {
-            await next.patchFile(envFile, envContent)
-          }
-        })
+        try {
+          await check(async () => {
+            expect(await browser.elementByCss('p').text()).toBe('ipad')
+            return 'success'
+          }, /success/)
+        } finally {
+          await next.patchFile(envFile, envContent)
+        }
+      })
 
-        it('should update server components pages when env files is changed (edge)', async () => {
-          const envContent = await next.readFile(envFile)
-          const browser = await next.browser('/env/edge')
-          expect(await browser.elementByCss('p').text()).toBe('mac')
-          await next.patchFile(envFile, 'MY_DEVICE="ipad"')
+      it('should update server components pages when env files is changed (edge)', async () => {
+        const envContent = await next.readFile(envFile)
+        const browser = await next.browser('/env/edge')
+        expect(await browser.elementByCss('p').text()).toBe('mac')
+        await next.patchFile(envFile, 'MY_DEVICE="ipad"')
 
-          try {
-            await check(async () => {
-              expect(await browser.elementByCss('p').text()).toBe('ipad')
-              return 'success'
-            }, /success/)
-          } finally {
-            await next.patchFile(envFile, envContent)
-          }
-        })
-      }
+        try {
+          await check(async () => {
+            expect(await browser.elementByCss('p').text()).toBe('ipad')
+            return 'success'
+          }, /success/)
+        } finally {
+          await next.patchFile(envFile, envContent)
+        }
+      })
 
       it('should have no unexpected action error for hmr', async () => {
         expect(next.cliOutput).not.toContain('Unexpected action')