revert "Apply react-server condition for pages api (#57459)" (#57500)

This reverts commit 6b18f397cb.

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packages/next/src/build/webpack-config.ts

@@ -454,12 +454,13 @@ export default async function getBaseWebpackConfig(
       ].filter(Boolean)
     : []
 
-  const swcLoaderForMiddlewareLayer =
-    // When using Babel, we will have to use SWC to do the optimization
-    // for middleware to tree shake the unused default optimized imports like "next/server".
-    // This will cause some performance overhead but
-    // acceptable as Babel will not be recommended.
-    [swcServerLayerLoader, babelLoader].filter(Boolean)
+  const swcLoaderForMiddlewareLayer = useSWCLoader
+    ? swcServerLayerLoader
+    : // When using Babel, we will have to use SWC to do the optimization
+      // for middleware to tree shake the unused default optimized imports like "next/server".
+      // This will cause some performance overhead but
+      // acceptable as Babel will not be recommended.
+      [swcServerLayerLoader, babelLoader]
 
   // client components layers: SSR + browser
   const swcLoaderForClientLayer = [
@@ -487,9 +488,16 @@ export default async function getBaseWebpackConfig(
       : []),
   ]
 
-  // Loader for API routes will also apply react-server export condition for bundling,
-  // and the API checks for server side only APIs.
-  const loaderForAPIRoutes = [swcServerLayerLoader, babelLoader].filter(Boolean)
+  // Loader for API routes needs to be differently configured as it shouldn't
+  // have RSC transpiler enabled, so syntax checks such as invalid imports won't
+  // be performed.
+  const loaderForAPIRoutes =
+    hasAppDir && useSWCLoader
+      ? getSwcLoader({
+          serverComponents: false,
+          isReactServerLayer: false,
+        })
+      : defaultLoaders.babel
 
   const pageExtensions = config.pageExtensions
 

test/e2e/app-dir/rsc-basic/pages/api/import-test.js

@@ -1,3 +1,7 @@
+// You can still import React and Next's client component APIs from the server
+// they won't be poisoned by the environment.
+// eslint-disable-next-line no-unused-vars
+import { useState } from 'react'
 import 'next/headers'
 
 export default function (_, res) {

test/e2e/module-layer/index.test.ts

@@ -1,5 +1,5 @@
 import { createNextDescribe } from 'e2e-utils'
-import { check, getRedboxSource, hasRedbox } from 'next-test-utils'
+import { getRedboxSource, hasRedbox } from 'next-test-utils'
 
 createNextDescribe(
   'module layer',
@@ -68,49 +68,51 @@ createNextDescribe(
     // Should error for using mixed (with client-only) in server targets
     if (isNextDev) {
       describe('no server-only in server targets', () => {
-        it('should error when import client-only in middleware', async () => {
-          const middlewareFile = 'middleware.js'
-          const middlewareContent = await next.readFile(middlewareFile)
+        const middlewareFile = 'middleware.js'
+        // const pagesApiFile = 'pages/api/hello.js'
+        let middlewareContent = ''
+        // let pagesApiContent = ''
+
+        beforeAll(async () => {
+          await next.stop()
+
+          middlewareContent = await next.readFile(middlewareFile)
+          // pagesApiContent = await next.readFile(pagesApiFile)
+
           await next.patchFile(
             middlewareFile,
-            middlewareContent.replace(
-              "// import './lib/mixed-lib'",
-              "import './lib/mixed-lib'"
-            )
+            middlewareContent
+              // .replace("import 'server-only'", "// import 'server-only'")
+              .replace(
+                "// import './lib/mixed-lib'",
+                "import './lib/mixed-lib'"
+              )
           )
+
+          // await next.patchFile(
+          //   pagesApiFile,
+          //   pagesApiContent
+          //     .replace("import 'server-only'", "// import 'server-only'")
+          //     .replace(
+          //       "// import '../../lib/mixed-lib'",
+          //       "import '../../lib/mixed-lib'"
+          //     )
+          // )
+
+          await next.start()
+        })
+        afterAll(async () => {
+          await next.patchFile(middlewareFile, middlewareContent)
+          // await next.patchFile(pagesApiFile, pagesApiContent)
+        })
+
+        it('should error when import client-only in middleware', async () => {
           const browser = await next.browser('/')
 
           expect(await hasRedbox(browser, true)).toBe(true)
           expect(await getRedboxSource(browser)).toContain(
             `You're importing a component that imports client-only. It only works in a Client Component but none of its parents are marked with "use client", so they're Server Components by default.`
           )
-
-          await next.patchFile(middlewareFile, middlewareContent)
-        })
-
-        it('should error when import client-only in pages/api', async () => {
-          const pagesApiFile = 'pages/api/mixed.js'
-          const pagesApiContent = await next.readFile(pagesApiFile)
-          await next.patchFile(
-            pagesApiFile,
-            pagesApiContent.replace(
-              "// import 'client-only'",
-              "import 'client-only'"
-            )
-          )
-
-          const existingCliOutputLength = next.cliOutput.length
-          await check(async () => {
-            await next.fetch('/api/mixed')
-            const newCliOutput = next.cliOutput.slice(existingCliOutputLength)
-            expect(newCliOutput).toContain('./pages/api/mixed.js')
-            expect(newCliOutput).toContain(
-              `You're importing a component that imports client-only. It only works in a Client Component but none of its parents are marked with "use client", so they're Server Components by default.`
-            )
-            return 'success'
-          }, 'success')
-
-          await next.patchFile(pagesApiFile, pagesApiContent)
         })
       })
     }

test/e2e/module-layer/pages/api/mixed.js

@@ -1,4 +1,4 @@
-// import 'client-only'
+import '../../lib/mixed-lib'
 
 export default function handler(req, res) {
   return res.send('pages/api/mixed.js:')