Add decoratorMetadata flag if enabled by tsconfig (vercel#32914)

fixes vercel#32913
Adds support for decorator metadata in SWC when enabled through ts/jsconfig.

## Bug

- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`

## Feature

- [x] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [x] Related issues linked using `fixes #number`
- [x] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have helpful link attached, see `contributing.md`

## Documentation / Examples

- [ ] Make sure the linting passes by running `yarn lint`


Co-authored-by: JJ Kasper <[email protected]>

Author: sannajammeh

.eslintignore

@@ -26,6 +26,7 @@ packages/next-env/**/*.d.ts
 packages/create-next-app/templates/**
 test/integration/eslint/**
 test/development/basic/legacy-decorators/**/*
+test/production/emit-decorator-metadata/**/*.js
 test-timings.json
 packages/next-swc/crates/**
 bench/nested-deps/pages/**

packages/next/build/swc/options.js

@@ -21,6 +21,9 @@ export function getBaseSWCOptions({
   const enableDecorators = Boolean(
     jsConfig?.compilerOptions?.experimentalDecorators
   )
+  const emitDecoratorMetadata = Boolean(
+    jsConfig?.compilerOptions?.emitDecoratorMetadata
+  )
   return {
     jsc: {
       ...(resolvedBaseUrl && paths
@@ -47,6 +50,7 @@ export function getBaseSWCOptions({
             }
           : {}),
         legacyDecorator: enableDecorators,
+        decoratorMetadata: emitDecoratorMetadata,
         react: {
           importSource: jsConfig?.compilerOptions?.jsxImportSource || 'react',
           runtime: 'automatic',

test/production/emit-decorator-metadata/app/jsconfig.json

@@ -0,0 +1,6 @@
+{
+  "compilerOptions": {
+    "experimentalDecorators": true,
+    "emitDecoratorMetadata": true
+  }
+}

test/production/emit-decorator-metadata/app/pages/api/[[...params]].js

@@ -0,0 +1,14 @@
+import { createHandler, Get, Param } from '@storyofams/next-api-decorators'
+
+class HelloHandler {
+  @Get('/:myParam')
+  // This fails due to library looking for Reflect.getMetadata("design:paramtypes", ...).
+  // Design:paramtypes is never emitted due to missing SWC flag.
+  async get(@Param('myParam') myParam) {
+    return {
+      myParam,
+    }
+  }
+}
+
+export default createHandler(HelloHandler)

test/production/emit-decorator-metadata/app/pages/index.js

@@ -0,0 +1,26 @@
+import React from 'react'
+import 'reflect-metadata'
+import { container, singleton } from 'tsyringe'
+
+@singleton()
+class HelloService {
+  getHello() {
+    return 'Hello, world!'
+  }
+}
+
+const helloService = container.resolve(HelloService)
+
+export default function Home() {
+  const message = helloService.getHello()
+
+  return <p id="message">{message}</p>
+}
+
+export function getServerSideProps() {
+  return {
+    props: {
+      now: Date.now(),
+    },
+  }
+}

test/production/emit-decorator-metadata/index.test.ts

@@ -0,0 +1,47 @@
+import { join } from 'path'
+import webdriver from 'next-webdriver'
+import { createNext, FileRef } from 'e2e-utils'
+import { NextInstance } from 'test/lib/next-modes/base'
+import { BrowserInterface } from 'test/lib/browsers/base'
+import { fetchViaHTTP } from 'next-test-utils'
+
+describe('emitDecoratorMetadata SWC option', () => {
+  let next: NextInstance
+
+  beforeAll(async () => {
+    next = await createNext({
+      files: {
+        'jsconfig.json': new FileRef(join(__dirname, 'app/jsconfig.json')),
+        pages: new FileRef(join(__dirname, 'app/pages')),
+      },
+      dependencies: {
+        '@storyofams/next-api-decorators': '1.6.0',
+        'reflect-metadata': '0.1.13',
+        'path-to-regexp': '6.2.0',
+        tsyringe: '4.6.0',
+      },
+    })
+  })
+
+  afterAll(() => next.destroy())
+
+  it('should compile with emitDecoratorMetadata enabled', async () => {
+    let browser: BrowserInterface
+    try {
+      browser = await webdriver(next.appPort, '/')
+      const message = await browser.elementByCss('#message').text()
+
+      expect(message).toBe('Hello, world!')
+    } finally {
+      if (browser) {
+        await browser.close()
+      }
+    }
+  })
+
+  it('should compile with emitDecoratorMetadata enabled for API', async () => {
+    const res = await fetchViaHTTP(next.url, '/api/something')
+    expect(res.status).toBe(200)
+    expect(await res.json()).toEqual({ myParam: 'something' })
+  })
+})