fix(build): ensure cjs re-exports can be properly detected when impor…

…ted from esm

package.json

@@ -89,7 +89,7 @@
     "prettier": "^2.7.1",
     "pug": "^3.0.1",
     "puppeteer": "^19.2.2",
-    "rollup": "~3.2.3",
+    "rollup": "~3.10.0",
     "rollup-plugin-node-builtins": "^2.1.2",
     "rollup-plugin-node-globals": "^1.4.0",
     "rollup-plugin-polyfill-node": "^0.11.0",

rollup.config.mjs

@@ -195,6 +195,10 @@ function createConfig(format, output, plugins = []) {
         ]
       : []
 
+  if (format === 'cjs') {
+    nodePlugins.push(cjsReExportsPatchPlugin())
+  }
+
   return {
     input: resolve(entryFile),
     // Global and Browser ESM builds inlines everything so that they can be
@@ -329,3 +333,46 @@ function createMinifiedConfig(format) {
     ]
   )
 }
+
+// temporary patch for https://github.com/nodejs/cjs-module-lexer/issues/79
+//
+// When importing a cjs module from esm, Node.js uses cjs-module-lexer to
+// detect * re-exports from other packages. However, the detection logic is
+// fragile and breaks when Rollup generates different code for the re-exports.
+// We were locked on an old version of Rollup because of this.
+//
+// The latest versions of Node ships an updated version of cjs-module-lexer that
+// has fixed https://github.com/nodejs/cjs-module-lexer/issues/38, however we
+// still need to support older versions of Node that does not have the latest
+// version of cjs-module-lexer (Node < 14.18)
+//
+// At the same time, we want to upgrade to Rollup 3 so we are not forever locked
+// on an old version of Rollup.
+//
+// What this patch does:
+// 1. Rewrite the for...in loop to Object.keys() so cjs-module-lexer can find it
+//    The for...in loop is only used when output.externalLiveBindings is set to
+//    false, and we do want to set it to false to avoid perf costs during SSR.
+// 2. Also remove exports.hasOwnProperty check, which breaks the detection in
+//    Node.js versions that
+//
+// TODO in the future, we should no longer rely on this if we inline all deps
+// in the main `vue` package.
+function cjsReExportsPatchPlugin() {
+  const matcher =
+    /for \(var k in (\w+)\) {(\s+if \(k !== 'default') && !exports.hasOwnProperty\(k\)(\) exports\[k\] = (?:\w+)\[k\];\s+)}/
+  return {
+    name: 'patch-cjs-re-exports',
+    renderChunk(code, _, options) {
+      if (matcher.test(code)) {
+        return code.replace(matcher, (_, r1, r2, r3) => {
+          return `Object.keys(${r1}).forEach(function(k) {${r2}${r3}});`
+        })
+      } else if (options.file.endsWith('/vue.cjs.js')) {
+        // make sure we don't accidentally miss the rewrite in case Rollup
+        // changes the output again.
+        throw new Error('cjs build re-exports rewrite failed.')
+      }
+    }
+  }
+}