From 04c06e678f3c5dcfd5e705f744f367c73ee969d9 Mon Sep 17 00:00:00 2001
From: Alec Larson <1925840+aleclarson@users.noreply.github.com>
Date: Fri, 25 Jun 2021 15:14:23 -0400
Subject: [PATCH] feat(ssr): respect `resolve.dedupe` in production

---
 packages/vite/src/node/plugins/index.ts       |  4 ++
 .../vite/src/node/plugins/ssrRequireHook.ts   | 42 +++++++++++++++++++
 2 files changed, 46 insertions(+)
 create mode 100644 packages/vite/src/node/plugins/ssrRequireHook.ts

diff --git a/packages/vite/src/node/plugins/index.ts b/packages/vite/src/node/plugins/index.ts
index cf982fcd0b4482..a2f24f65b6a104 100644
--- a/packages/vite/src/node/plugins/index.ts
+++ b/packages/vite/src/node/plugins/index.ts
@@ -14,6 +14,7 @@ import { dynamicImportPolyfillPlugin } from './dynamicImportPolyfill'
 import { webWorkerPlugin } from './worker'
 import { preAliasPlugin } from './preAlias'
 import { definePlugin } from './define'
+import { ssrRequireHookPlugin } from './ssrRequireHook'
 
 export async function resolvePlugins(
   config: ResolvedConfig,
@@ -40,6 +41,9 @@ export async function resolvePlugins(
       ssrTarget: config.ssr?.target,
       asSrc: true
     }),
+    config.ssr && config.command === 'build'
+      ? ssrRequireHookPlugin(config)
+      : null,
     htmlInlineScriptProxyPlugin(),
     cssPlugin(config),
     config.esbuild !== false ? esbuildPlugin(config.esbuild) : null,
diff --git a/packages/vite/src/node/plugins/ssrRequireHook.ts b/packages/vite/src/node/plugins/ssrRequireHook.ts
new file mode 100644
index 00000000000000..e3d2023828bfc5
--- /dev/null
+++ b/packages/vite/src/node/plugins/ssrRequireHook.ts
@@ -0,0 +1,42 @@
+import MagicString from 'magic-string'
+import { ResolvedConfig } from '..'
+import { Plugin } from '../plugin'
+
+const impl = `;(function() {
+  const Module = require("module")
+  const resolveFilename = Module._resolveFilename
+  const dedupe = DEDUPE_IDS
+  Module._resolveFilename = function (request, parent, isMain, options) {
+    if (request[0] !== "." && request[0] !== "/") {
+      const parts = request.split("/")
+      const pkgName = parts[0][0] === "@" ? parts[0] + "/" + parts[1] : parts[0]
+      if (dedupe.includes(pkgName)) {
+        // Use this module as the parent.
+        parent = module
+      }
+    }
+    return resolveFilename(request, parent, isMain, options)
+  }
+})();
+`
+
+export function ssrRequireHookPlugin(config: ResolvedConfig): Plugin {
+  return {
+    name: 'vite:ssr-require-hook',
+    transform(code, id) {
+      const moduleInfo = this.getModuleInfo(id)
+      if (moduleInfo?.isEntry) {
+        const s = new MagicString(code)
+        s.prepend(
+          impl.replace('DEDUPE_IDS', JSON.stringify(config.resolve.dedupe))
+        )
+        return {
+          code: s.toString(),
+          map: s.generateMap({
+            source: id
+          })
+        }
+      }
+    }
+  }
+}