From 8e5a05b993998c2c20d4ba159926114f0c0a884e Mon Sep 17 00:00:00 2001
From: Ben Demboski <demboskb@gmail.com>
Date: Tue, 27 Apr 2021 10:14:09 -0700
Subject: [PATCH] Better error message with webpack v4 installed

Detect when a too-old version of webpack is installed upfront, rather than producing a more cryptic error later in the build process when some incompatible data is encountered.
---
 packages/webpack/package.json         | 1 +
 packages/webpack/src/ember-webpack.ts | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/packages/webpack/package.json b/packages/webpack/package.json
index 24af40eb6..fba55e6b6 100644
--- a/packages/webpack/package.json
+++ b/packages/webpack/package.json
@@ -39,6 +39,7 @@
     "lodash": "^4.17.10",
     "mini-css-extract-plugin": "^1.3.2",
     "pkg-up": "^3.1.0",
+    "semver": "^7.3.5",
     "source-map-url": "^0.4.0",
     "style-loader": "^2.0.0",
     "terser": "^5.5.1",
diff --git a/packages/webpack/src/ember-webpack.ts b/packages/webpack/src/ember-webpack.ts
index 9f16e89ce..d2dc34445 100644
--- a/packages/webpack/src/ember-webpack.ts
+++ b/packages/webpack/src/ember-webpack.ts
@@ -26,6 +26,7 @@ import { HTMLEntrypoint } from './html-entrypoint';
 import { StatSummary } from './stat-summary';
 import crypto from 'crypto';
 import type { HbsLoaderConfig } from '@embroider/hbs-loader';
+import semverSatisfies from 'semver/functions/satisfies';
 
 const debug = makeDebug('embroider:debug');
 
@@ -83,6 +84,10 @@ const Webpack: Packager<Options> = class Webpack implements PackagerInstance {
     private consoleWrite: (msg: string) => void,
     options?: Options
   ) {
+    if (!semverSatisfies(webpack.version, '^5.0.0')) {
+      throw new Error(`@embroider/webpack requires webpack@^5.0.0, but found version ${webpack.version}`);
+    }
+
     this.pathToVanillaApp = realpathSync(pathToVanillaApp);
     this.extraConfig = options?.webpackConfig;
     this.publicAssetURL = options?.publicAssetURL;