From 8cc862ebfc4ee0dbcfe08ba86913a6f57be24166 Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Fri, 20 Nov 2020 10:25:24 +0100
Subject: [PATCH] cli: enable transformation of workspace packages outside the
 workspace root

---
 packages/cli/src/lib/bundler/config.ts     | 34 ++++++++++++++++++----
 packages/cli/src/lib/bundler/transforms.ts | 21 ++++++++-----
 2 files changed, 42 insertions(+), 13 deletions(-)

diff --git a/packages/cli/src/lib/bundler/config.ts b/packages/cli/src/lib/bundler/config.ts
index 9e150e0ccb..b5a27dd624 100644
--- a/packages/cli/src/lib/bundler/config.ts
+++ b/packages/cli/src/lib/bundler/config.ts
@@ -70,13 +70,27 @@ async function readBuildInfo() {
   };
 }
 
+async function loadLernaPackages(): Promise<
+  { name: string; location: string }[]
+> {
+  const LernaProject = require('@lerna/project');
+  const project = new LernaProject(cliPaths.targetDir);
+  return project.getPackages();
+}
+
 export async function createConfig(
   paths: BundlingPaths,
   options: BundlingOptions,
 ): Promise<webpack.Configuration> {
   const { checksEnabled, isDev, frontendConfig } = options;
 
-  const { plugins, loaders } = transforms(options);
+  const packages = await loadLernaPackages();
+  const { plugins, loaders } = transforms({
+    ...options,
+    externalTransforms: packages.map(({ name }) =>
+      cliPaths.resolveTargetRoot('node_modules', name),
+    ),
+  });
 
   const baseUrl = frontendConfig.getString('app.baseUrl');
   const validBaseUrl = new URL(baseUrl);
@@ -159,6 +173,10 @@ export async function createConfig(
       alias: {
         'react-dom': '@hot-loader/react-dom',
       },
+      // Enables proper resolution of packages when linking in external packages.
+      // Without this the packages would depend on dependencies in the node_modules
+      // of the external packages themselves, leading to module duplication
+      symlinks: false,
     },
     module: {
       rules: loaders,
@@ -181,17 +199,20 @@ export async function createBackendConfig(
 ): Promise<webpack.Configuration> {
   const { checksEnabled, isDev } = options;
 
-  const { loaders } = transforms(options);
-
   // Find all local monorepo packages and their node_modules, and mark them as external.
-  const LernaProject = require('@lerna/project');
-  const project = new LernaProject(cliPaths.targetDir);
-  const packages = await project.getPackages();
+  const packages = await await loadLernaPackages();
   const localPackageNames = packages.map((p: any) => p.name);
   const moduleDirs = packages.map((p: any) =>
     resolvePath(p.location, 'node_modules'),
   );
 
+  const { loaders } = transforms({
+    ...options,
+    externalTransforms: packages.map(({ name }) =>
+      cliPaths.resolveTargetRoot('node_modules', name),
+    ),
+  });
+
   return {
     mode: isDev ? 'development' : 'production',
     profile: false,
@@ -240,6 +261,7 @@ export async function createBackendConfig(
       alias: {
         'react-dom': '@hot-loader/react-dom',
       },
+      symlinks: false, // See frontend config, added here for the same reason
     },
     module: {
       rules: loaders,
diff --git a/packages/cli/src/lib/bundler/transforms.ts b/packages/cli/src/lib/bundler/transforms.ts
index d8186dac66..6dc32e6563 100644
--- a/packages/cli/src/lib/bundler/transforms.ts
+++ b/packages/cli/src/lib/bundler/transforms.ts
@@ -16,7 +16,6 @@
 
 import webpack, { Module, Plugin } from 'webpack';
 import MiniCssExtractPlugin from 'mini-css-extract-plugin';
-import { BundlingOptions, BackendBundlingOptions } from './types';
 import { svgrTemplate } from '../svgrTemplate';
 
 type Transforms = {
@@ -24,17 +23,25 @@ type Transforms = {
   plugins: Plugin[];
 };
 
-export const transforms = (
-  options: BundlingOptions | BackendBundlingOptions,
-): Transforms => {
-  const { isDev } = options;
+type TransformOptions = {
+  isDev: boolean;
+  // External paths that should be transformed
+  externalTransforms: string[];
+};
+
+export const transforms = (options: TransformOptions): Transforms => {
+  const { isDev, externalTransforms } = options;
 
   const extraTransforms = isDev ? ['react-hot-loader'] : [];
 
+  const transformExcludeCondition = {
+    and: [/node_modules/, { not: externalTransforms }],
+  };
+
   const loaders = [
     {
       test: /\.(tsx?)$/,
-      exclude: /node_modules/,
+      exclude: transformExcludeCondition,
       loader: require.resolve('@sucrase/webpack-loader'),
       options: {
         transforms: ['typescript', 'jsx', ...extraTransforms],
@@ -43,7 +50,7 @@ export const transforms = (
     },
     {
       test: /\.(jsx?|mjs)$/,
-      exclude: /node_modules/,
+      exclude: transformExcludeCondition,
       loader: require.resolve('@sucrase/webpack-loader'),
       options: {
         transforms: ['jsx', ...extraTransforms],