fix(rsc): support cjs on module runner

packages/plugin-rsc/e2e/basic.test.ts

@@ -63,7 +63,7 @@ test.describe('dev-non-optimized-cjs', () => {
   test('show warning', async ({ page }) => {
     await page.goto(f.url())
     expect(f.proc().stderr()).toContain(
-      `[vite-rsc] found non-optimized CJS dependency in 'ssr' environment.`,
+      `Found non-optimized CJS dependency in 'ssr' environment.`,
     )
   })
 })

packages/plugin-rsc/package.json

@@ -44,7 +44,6 @@
     "magic-string": "^0.30.17",
     "periscopic": "^4.0.2",
     "turbo-stream": "^3.1.0",
-    "use-sync-external-store": "^1.5.0",
     "vitefu": "^1.1.1"
   },
   "devDependencies": {

packages/plugin-rsc/src/plugin.ts

@@ -21,7 +21,7 @@ import {
   normalizePath,
   parseAstAsync,
 } from 'vite'
-import { crawlFrameworkPkgs, findClosestPkgJsonPath } from 'vitefu'
+import { crawlFrameworkPkgs } from 'vitefu'
 import vitePluginRscCore from './core/plugin'
 import {
   type TransformWrapExportFilter,
@@ -33,6 +33,8 @@ import {
 import { generateEncryptionKey, toBase64 } from './utils/encryption-utils'
 import { createRpcServer } from './utils/rpc'
 import { normalizeViteImportAnalysisUrl, prepareError } from './vite-utils'
+import { cjsModuleRunnerPlugin } from './plugins/cjs'
+import { evalValue, parseIdQuery } from './plugins/utils'
 
 // state for build orchestration
 let serverReferences: Record<string, string> = {}
@@ -882,42 +884,10 @@ globalThis.AsyncLocalStorage = __viteRscAyncHooks.AsyncLocalStorage;
     ...(rscPluginOptions.validateImports !== false
       ? [validateImportPlugin()]
       : []),
-    ...vendorUseSyncExternalStorePlugin(),
     scanBuildStripPlugin(),
-    detectNonOptimizedCjsPlugin(),
+    ...cjsModuleRunnerPlugin(),
   ]
 }
-function detectNonOptimizedCjsPlugin(): Plugin {
-  return {
-    name: 'rsc:detect-non-optimized-cjs',
-    apply: 'serve',
-    async transform(code, id) {
-      if (
-        id.includes('/node_modules/') &&
-        !id.startsWith(this.environment.config.cacheDir) &&
-        /\b(require|exports)\b/.test(code)
-      ) {
-        id = parseIdQuery(id).filename
-        let isEsm = id.endsWith('.mjs')
-        if (id.endsWith('.js')) {
-          const pkgJsonPath = await findClosestPkgJsonPath(path.dirname(id))
-          if (pkgJsonPath) {
-            const pkgJson = JSON.parse(
-              fs.readFileSync(pkgJsonPath, 'utf-8'),
-            ) as { type?: string }
-            isEsm = pkgJson.type === 'module'
-          }
-        }
-        if (!isEsm) {
-          this.warn(
-            `[vite-rsc] found non-optimized CJS dependency in '${this.environment.name}' environment. ` +
-              `It is recommended to manually add the dependency to 'environments.${this.environment.name}.optimizeDeps.include'.`,
-          )
-        }
-      }
-    },
-  }
-}
 
 function scanBuildStripPlugin(): Plugin {
   return {
@@ -1993,23 +1963,6 @@ function generateResourcesCode(depsCode: string) {
   `
 }
 
-// https://github.com/vitejs/vite/blob/ea9aed7ebcb7f4be542bd2a384cbcb5a1e7b31bd/packages/vite/src/node/utils.ts#L1469-L1475
-function evalValue<T = any>(rawValue: string): T {
-  const fn = new Function(`
-    var console, exports, global, module, process, require
-    return (\n${rawValue}\n)
-  `)
-  return fn()
-}
-
-// https://github.com/vitejs/vite-plugin-vue/blob/06931b1ea2b9299267374cb8eb4db27c0626774a/packages/plugin-vue/src/utils/query.ts#L13
-function parseIdQuery(id: string) {
-  if (!id.includes('?')) return { filename: id, query: {} }
-  const [filename, rawQuery] = id.split(`?`, 2) as [string, string]
-  const query = Object.fromEntries(new URLSearchParams(rawQuery))
-  return { filename, query }
-}
-
 export async function transformRscCssExport(options: {
   ast: Awaited<ReturnType<typeof parseAstAsync>>
   code: string
@@ -2125,41 +2078,6 @@ function validateImportPlugin(): Plugin {
   }
 }
 
-function vendorUseSyncExternalStorePlugin(): Plugin[] {
-  // vendor and optimize use-sync-external-store out of the box
-  // since this is a common enough cjs, which tends to break
-  // other packages (e.g. swr, @tanstack/react-store)
-
-  // https://github.com/facebook/react/blob/c499adf8c89bbfd884f4d3a58c4e510001383525/packages/use-sync-external-store/package.json#L5-L20
-  const exports = [
-    'use-sync-external-store',
-    'use-sync-external-store/with-selector',
-    'use-sync-external-store/with-selector.js',
-    'use-sync-external-store/shim',
-    'use-sync-external-store/shim/index.js',
-    'use-sync-external-store/shim/with-selector',
-    'use-sync-external-store/shim/with-selector.js',
-  ]
-
-  return [
-    {
-      name: 'rsc:vendor-use-sync-external-store',
-      apply: 'serve',
-      config() {
-        return {
-          environments: {
-            ssr: {
-              optimizeDeps: {
-                include: exports.map((e) => `${PKG_NAME} > ${e}`),
-              },
-            },
-          },
-        }
-      },
-    },
-  ]
-}
-
 function sortObject<T extends object>(o: T) {
   return Object.fromEntries(
     Object.entries(o).sort(([a], [b]) => a.localeCompare(b)),

packages/plugin-rsc/src/plugins/cjs.ts

@@ -0,0 +1,87 @@
+import { parseAstAsync, type Plugin } from 'vite'
+import { parseIdQuery } from './utils'
+import { findClosestPkgJsonPath } from 'vitefu'
+import path from 'node:path'
+import fs from 'node:fs'
+import * as esModuleLexer from 'es-module-lexer'
+import { transformCjsToEsm } from '../transforms/cjs'
+
+export function cjsModuleRunnerPlugin(): Plugin[] {
+  // use-sync-external-store is known to work fine so don't show warning
+  const warnedPackages = new Set<string>(['use-sync-external-store'])
+
+  return [
+    {
+      name: 'cjs-module-runner-transform',
+      apply: 'serve',
+      applyToEnvironment: (env) => env.config.dev.moduleRunnerTransform,
+      async transform(code, id) {
+        if (
+          id.includes('/node_modules/') &&
+          !id.startsWith(this.environment.config.cacheDir) &&
+          /\b(require|exports)\b/.test(code)
+        ) {
+          id = parseIdQuery(id).filename
+          if (!/\.[cm]?js$/.test(id)) return
+
+          // skip genuine esm
+          if (id.endsWith('.mjs')) return
+          if (id.endsWith('.js')) {
+            const pkgJsonPath = await findClosestPkgJsonPath(path.dirname(id))
+            if (pkgJsonPath) {
+              const pkgJson = JSON.parse(
+                fs.readFileSync(pkgJsonPath, 'utf-8'),
+              ) as { type?: string }
+              if (pkgJson.type === 'module') return
+            }
+          }
+
+          // skip faux esm (e.g. from "module" field)
+          const [, , , hasModuleSyntax] = esModuleLexer.parse(code)
+          if (hasModuleSyntax) return
+
+          // warning once per package
+          const packageKey = extractPackageKey(id)
+          if (!warnedPackages.has(packageKey)) {
+            this.warn(
+              `Found non-optimized CJS dependency in '${this.environment.name}' environment. ` +
+                `It is recommended to add the dependency to 'environments.${this.environment.name}.optimizeDeps.include'.`,
+            )
+            warnedPackages.add(packageKey)
+          }
+
+          const ast = await parseAstAsync(code)
+          const result = transformCjsToEsm(code, ast)
+          const output = result.output
+          // TODO: can we use cjs-module-lexer to properly define named exports?
+          // for re-exports, we need to eagerly transform dependencies though.
+          // https://github.com/nodejs/node/blob/f3adc11e37b8bfaaa026ea85c1cf22e3a0e29ae9/lib/internal/modules/esm/translators.js#L382-L409
+          output.append(`__vite_ssr_exportAll__(module.exports)`)
+          return {
+            code: output.toString(),
+            map: output.generateMap({ hires: 'boundary' }),
+          }
+        }
+      },
+    },
+  ]
+}
+
+function extractPackageKey(id: string): string {
+  // .../.yarn/cache/abc/... => abc
+  const yarnMatch = id.match(/\/.yarn\/cache\/([^/]+)/)
+  if (yarnMatch) {
+    return yarnMatch[1]!
+  }
+  // .../node_modules/@x/y/... => @x/y
+  // .../node_modules/x/... => x
+  if (id.includes('/node_modules')) {
+    id = id.split('/node_modules/').at(-1)!
+    let [x, y] = id.split('/')
+    if (x!.startsWith('@')) {
+      return `${x}/${y}`
+    }
+    return x!
+  }
+  return id
+}

packages/plugin-rsc/src/plugins/utils.ts

@@ -0,0 +1,21 @@
+// https://github.com/vitejs/vite/blob/ea9aed7ebcb7f4be542bd2a384cbcb5a1e7b31bd/packages/vite/src/node/utils.ts#L1469-L1475
+export function evalValue<T = any>(rawValue: string): T {
+  const fn = new Function(`
+    var console, exports, global, module, process, require
+    return (\n${rawValue}\n)
+  `)
+  return fn()
+}
+
+// https://github.com/vitejs/vite-plugin-vue/blob/06931b1ea2b9299267374cb8eb4db27c0626774a/packages/plugin-vue/src/utils/query.ts#L13
+export function parseIdQuery(id: string): {
+  filename: string
+  query: {
+    [k: string]: string
+  }
+} {
+  if (!id.includes('?')) return { filename: id, query: {} }
+  const [filename, rawQuery] = id.split(`?`, 2) as [string, string]
+  const query = Object.fromEntries(new URLSearchParams(rawQuery))
+  return { filename, query }
+}

packages/plugin-rsc/src/transforms/cjs.test.ts

@@ -0,0 +1,86 @@
+import { parseAstAsync } from 'vite'
+import { describe, expect, it } from 'vitest'
+import { debugSourceMap } from './test-utils'
+import { transformCjsToEsm } from './cjs'
+
+describe(transformCjsToEsm, () => {
+  async function testTransform(input: string) {
+    const ast = await parseAstAsync(input)
+    const { output } = transformCjsToEsm(input, ast)
+    if (!output.hasChanged()) {
+      return
+    }
+    if (process.env['DEBUG_SOURCEMAP']) {
+      await debugSourceMap(output)
+    }
+    return output.toString()
+  }
+
+  it('basic', async () => {
+    const input = `\
+exports.ok = true;
+`
+    expect(await testTransform(input)).toMatchInlineSnapshot(`
+      "const exports = {}; const module = { exports };
+      exports.ok = true;
+      "
+    `)
+  })
+
+  it('top-level re-export', async () => {
+    const input = `\
+if (true) {
+  module.exports = require('./cjs/use-sync-external-store.production.js');
+} else {
+  module.exports = require('./cjs/use-sync-external-store.development.js');
+}
+`
+    expect(await testTransform(input)).toMatchInlineSnapshot(`
+      "const exports = {}; const module = { exports };
+      if (true) {
+        module.exports = (await import('./cjs/use-sync-external-store.production.js'));
+      } else {
+        module.exports = (await import('./cjs/use-sync-external-store.development.js'));
+      }
+      "
+    `)
+  })
+
+  it('non top-level re-export', async () => {
+    const input = `\
+"production" !== process.env.NODE_ENV && (function() { 
+  var React = require("react");
+  var ReactDOM = require("react-dom");
+  exports.useSyncExternalStoreWithSelector = function () {}
+})()
+`
+    expect(await testTransform(input)).toMatchInlineSnapshot(`
+      "const exports = {}; const module = { exports };
+      const __cjs_to_esm_hoist_1 = await import("react-dom");
+      const __cjs_to_esm_hoist_0 = await import("react");
+      "production" !== process.env.NODE_ENV && (function() { 
+        var React = __cjs_to_esm_hoist_0;
+        var ReactDOM = __cjs_to_esm_hoist_1;
+        exports.useSyncExternalStoreWithSelector = function () {}
+      })()
+      "
+    `)
+  })
+
+  it('local require', async () => {
+    const input = `\
+{
+  const require = () => {};
+  require("test");
+}
+`
+    expect(await testTransform(input)).toMatchInlineSnapshot(`
+      "const exports = {}; const module = { exports };
+      {
+        const require = () => {};
+        require("test");
+      }
+      "
+    `)
+  })
+})