Resolve to real path before checking for path inequality

package.json

@@ -98,6 +98,7 @@
     "npm-run-all": "4.1.5",
     "nprogress": "0.2.0",
     "pixrem": "5.0.0",
+    "pnpm": "5.8.0",
     "postcss-nested": "4.2.1",
     "postcss-pseudoelements": "5.0.0",
     "postcss-short-size": "4.0.0",

packages/next/build/webpack-config.ts

@@ -1,7 +1,7 @@
 import { codeFrameColumns } from '@babel/code-frame'
 import ReactRefreshWebpackPlugin from '@next/react-refresh-utils/ReactRefreshWebpackPlugin'
 import crypto from 'crypto'
-import { readFileSync } from 'fs'
+import { readFileSync, realpathSync } from 'fs'
 import chalk from 'next/dist/compiled/chalk'
 import semver from 'next/dist/compiled/semver'
 import TerserPlugin from 'next/dist/compiled/terser-webpack-plugin'
@@ -665,7 +665,12 @@ export default async function getBaseWebpackConfig(
       // Same as above: if the package, when required from the root,
       // would be different from what the real resolution would use, we
       // cannot externalize it.
-      if (baseRes !== res) {
+      if (
+        !baseRes ||
+        (baseRes !== res &&
+          // if res and baseRes are symlinks they could point to the the same file
+          realpathSync(baseRes) !== realpathSync(res))
+      ) {
         return callback()
       }
     }

test/package-managers-tests/basic-pnpm/pages/about.js

@@ -0,0 +1,3 @@
+export default function About() {
+  return <div>About us</div>
+}

test/package-managers-tests/basic-pnpm/pages/about2.js

@@ -0,0 +1,3 @@
+export default function About2() {
+  return <div>About 2</div>
+}

test/package-managers-tests/basic-pnpm/pages/day/index.js

@@ -0,0 +1,3 @@
+export default function Day() {
+  return <div>Hello Day</div>
+}

test/package-managers-tests/basic-pnpm/pages/index.js

@@ -0,0 +1,11 @@
+import Link from 'next/link'
+export default function Home() {
+  return (
+    <div>
+      Hello World.{' '}
+      <Link href="/about">
+        <a>About</a>
+      </Link>
+    </div>
+  )
+}

test/package-managers-tests/basic-pnpm/test/index.test.js

@@ -0,0 +1,74 @@
+/* eslint-env jest */
+import { execSync } from 'child_process'
+import fs from 'fs-extra'
+import path from 'path'
+
+jest.setTimeout(100 * 1000)
+
+beforeAll(async () => {
+  await clean()
+})
+
+afterAll(async () => {
+  await clean()
+})
+
+test('pnpm installs', async () => {
+  const pnpm = getStdout('yarn bin pnpm')
+  exec(pnpm + ' init -y')
+  exec(pnpm + ' add next react react-dom')
+  await useLocalNextjs()
+  // exec('pnpm install')
+})
+
+test('nextjs builds with pnpm', () => {
+  const pnpx = getStdout(`yarn bin pnpx`)
+  exec(pnpx + ' next build')
+})
+
+const exec = (cmd) => {
+  return execSync(cmd, {
+    env: process.env,
+    shell: true,
+    stdio: 'inherit',
+    cwd: path.resolve(__dirname, '..'),
+  })
+}
+
+const getStdout = (cmd) => {
+  return execSync(cmd, {
+    env: process.env,
+    shell: true,
+    stdio: 'pipe',
+  })
+    .toString()
+    .trim()
+}
+
+async function useLocalNextjs() {
+  // installed nextjs
+  const nextPath = path.dirname(require.resolve('next/package.json'))
+
+  // repository root
+  const root = path.dirname(
+    require.resolve(path.resolve(process.cwd(), 'package.json'))
+  )
+
+  // local nextjs
+  const currentNextPath = path.resolve(root, 'packages/next')
+
+  // copy local nextjs to node_modules
+  await fs.copy(
+    path.resolve(currentNextPath, 'dist'),
+    path.resolve(nextPath, 'dist')
+  )
+
+  console.log('copied local nextjs to node_modules')
+}
+
+async function clean() {
+  // jest test cannot be found if a package.json exists in test directory
+  await fs.remove(path.resolve(__dirname, '../package.json'))
+  await fs.remove(path.resolve(__dirname, '../node_modules'))
+  await fs.remove(path.resolve(__dirname, '../pnpm-lock.yaml'))
+}

yarn.lock

@@ -12567,6 +12567,11 @@ pnp-webpack-plugin@1.6.4:
   dependencies:
     ts-pnp "^1.1.6"
 
+pnpm@5.8.0:
+  version "5.8.0"
+  resolved "https://registry.yarnpkg.com/pnpm/-/pnpm-5.8.0.tgz#a933d6c756efe8795b12004bbff1b82c622e771b"
+  integrity sha512-J2rAxEXnohwcDkR4KNI6UsYhDs9hJ/tje/BahHpXawi406pmxd6caJUXfRxZPbKvKdyVqfBRKhlX1vyhYbM8lQ==
+
 posix-character-classes@^0.1.0:
   version "0.1.1"
   resolved "https://registry.yarnpkg.com/posix-character-classes/-/posix-character-classes-0.1.1.tgz#01eac0fe3b5af71a2a6c02feabb8c1fef7e00eab"