improves baseUrl resolution in typescript monorepos

Typescript configuration can inherit from files above cwd in the
filesystem. If a baseUrl was declared in such a file, it would not be
picked up by the webpack config. This would force users to use the
next-transpile-module and duplicate configuration with unintuitive path
relations (see vercel#13197 for a detailed analysis)

If baseUrl is resolved it should be used instead of dir as the root
include for babel-resolve-loader.

packages/next/build/webpack-config.ts

@@ -52,6 +52,7 @@ import WebpackConformancePlugin, {
 } from './webpack/plugins/webpack-conformance-plugin'
 import { WellKnownErrorsPlugin } from './webpack/plugins/wellknown-errors-plugin'
 import { codeFrameColumns } from '@babel/code-frame'
+import { getTypeScriptConfiguration } from '../lib/typescript/getTypeScriptConfiguration'
 
 type ExcludesFalse = <T>(x: T | false) => x is T
 
@@ -250,7 +251,9 @@ export default async function getBaseWebpackConfig(
   let jsConfig
   // jsconfig is a subset of tsconfig
   if (useTypeScript) {
-    jsConfig = parseJsonFile(tsConfigPath)
+    const ts = (await import(typeScriptPath)) as typeof import('typescript')
+    const tsConfig = await getTypeScriptConfiguration(ts, tsConfigPath)
+    jsConfig = { compilerOptions: tsConfig.options }
   }
 
   const jsConfigPath = path.join(dir, 'jsconfig.json')
@@ -760,7 +763,9 @@ export default async function getBaseWebpackConfig(
       rules: [
         {
           test: /\.(tsx|ts|js|mjs|jsx)$/,
-          include: [dir, ...babelIncludeRegexes],
+          include: resolvedBaseUrl
+            ? [resolvedBaseUrl, ...babelIncludeRegexes]
+            : [dir, ...babelIncludeRegexes],
           exclude: (path: string) => {
             if (babelIncludeRegexes.some((r) => r.test(path))) {
               return false

test/integration/typescript-workspaces-paths/packages/lib/a/api.ts

@@ -0,0 +1 @@
+export default () => 'Hello from a'

test/integration/typescript-workspaces-paths/packages/lib/b/api.ts

@@ -0,0 +1 @@
+export default () => 'Hello from b'

test/integration/typescript-workspaces-paths/packages/lib/b/b-only.ts

@@ -0,0 +1 @@
+export default () => 'Hello from only b'

test/integration/typescript-workspaces-paths/packages/www/components/alias-to-d-ts.d.ts

@@ -0,0 +1 @@
+export default () => any

test/integration/typescript-workspaces-paths/packages/www/components/alias-to-d-ts.tsx

@@ -0,0 +1,3 @@
+export default () => {
+  return <>Not aliased to d.ts file</>
+}

test/integration/typescript-workspaces-paths/packages/www/components/hello.tsx

@@ -0,0 +1,5 @@
+import React from 'react'
+
+export function Hello() {
+  return <>Hello</>
+}

test/integration/typescript-workspaces-paths/packages/www/components/world.tsx

@@ -0,0 +1,5 @@
+import React from 'react'
+
+export function World(): JSX.Element {
+  return <>World</>
+}

test/integration/typescript-workspaces-paths/packages/www/next.config.js

@@ -0,0 +1,9 @@
+module.exports = {
+  webpack: function (config) {
+    return config
+  },
+  onDemandEntries: {
+    // Make sure entries are not getting disposed.
+    maxInactiveAge: 1000 * 60 * 60,
+  },
+}

test/integration/typescript-workspaces-paths/packages/www/pages/alias-to-d-ts.tsx

@@ -0,0 +1,10 @@
+import React from 'react'
+import NotAliasedToDTS from 'd-ts-alias'
+
+export default function HelloPage(): JSX.Element {
+  return (
+    <div>
+      <NotAliasedToDTS />
+    </div>
+  )
+}

test/integration/typescript-workspaces-paths/packages/www/pages/basic-alias.tsx

@@ -0,0 +1,9 @@
+import React from 'react'
+import { World } from '@c/world'
+export default function HelloPage(): JSX.Element {
+  return (
+    <div>
+      <World />
+    </div>
+  )
+}

test/integration/typescript-workspaces-paths/packages/www/pages/resolve-fallback.tsx

@@ -0,0 +1,5 @@
+import React from 'react'
+import api from '@lib/b-only'
+export default function ResolveOrder(): JSX.Element {
+  return <div>{api()}</div>
+}

test/integration/typescript-workspaces-paths/packages/www/pages/resolve-order.tsx

@@ -0,0 +1,5 @@
+import React from 'react'
+import api from '@lib/api'
+export default function ResolveOrder(): JSX.Element {
+  return <div>{api()}</div>
+}

test/integration/typescript-workspaces-paths/packages/www/pages/single-alias.tsx

@@ -0,0 +1,9 @@
+import { Hello } from '@mycomponent'
+
+export default function SingleAlias() {
+  return (
+    <div>
+      <Hello />
+    </div>
+  )
+}

test/integration/typescript-workspaces-paths/packages/www/test/index.test.js

@@ -0,0 +1,51 @@
+/* eslint-env jest */
+
+import { join } from 'path'
+import cheerio from 'cheerio'
+import { renderViaHTTP, findPort, launchApp, killApp } from 'next-test-utils'
+
+jest.setTimeout(1000 * 60 * 2)
+
+const appDir = join(__dirname, '..')
+let appPort
+let app
+
+async function get$(path, query) {
+  const html = await renderViaHTTP(appPort, path, query)
+  return cheerio.load(html)
+}
+
+describe('TypeScript Features', () => {
+  describe('default behavior', () => {
+    beforeAll(async () => {
+      appPort = await findPort()
+      app = await launchApp(appDir, appPort, {})
+    })
+    afterAll(() => killApp(app))
+
+    it('should alias components', async () => {
+      const $ = await get$('/basic-alias')
+      expect($('body').text()).toMatch(/World/)
+    })
+
+    it('should resolve the first item in the array first', async () => {
+      const $ = await get$('/resolve-order')
+      expect($('body').text()).toMatch(/Hello from a/)
+    })
+
+    it('should resolve the second item in as a fallback', async () => {
+      const $ = await get$('/resolve-fallback')
+      expect($('body').text()).toMatch(/Hello from only b/)
+    })
+
+    it('should resolve a single matching alias', async () => {
+      const $ = await get$('/single-alias')
+      expect($('body').text()).toMatch(/Hello/)
+    })
+
+    it('should not resolve to .d.ts files', async () => {
+      const $ = await get$('/alias-to-d-ts')
+      expect($('body').text()).toMatch(/Not aliased to d\.ts file/)
+    })
+  })
+})

test/integration/typescript-workspaces-paths/packages/www/tsconfig.json

@@ -0,0 +1,6 @@
+/* This is a single line comment to check if that works */
+{
+  "extends": "../../tsconfig.json",
+  "exclude": ["node_modules"],
+  "include": ["next-env.d.ts", "components", "pages"]
+}

test/integration/typescript-workspaces-paths/tsconfig.json

@@ -0,0 +1,30 @@
+/* This is a single line comment to check if that works */
+{
+  "compilerOptions": {
+    "baseUrl": ".",
+    "paths": {
+      "isomorphic-unfetch": ["packages/www/types/unfetch.d.ts"],
+      "@c/*": ["packages/www/components/*"],
+      "@lib/*": ["packages/lib/a/*", "packages/lib/b/*"],
+      "@mycomponent": ["packages/www/components/hello.tsx"],
+      "d-ts-alias": [
+        "packages/www/components/alias-to-d-ts.d.ts",
+        "packages/www/components/alias-to-d-ts.tsx"
+      ]
+      // This is a single line comment to check if that works
+    },
+    "esModuleInterop": true,
+    "module": "esnext",
+    "jsx": "preserve",
+    "target": "es5",
+    "lib": ["dom", "dom.iterable", "esnext"],
+    "allowJs": true,
+    "skipLibCheck": true,
+    "strict": true,
+    "forceConsistentCasingInFileNames": true,
+    "noEmit": true,
+    "moduleResolution": "node",
+    "resolveJsonModule": true,
+    "isolatedModules": true
+  }
+}