fix: fallback terser to main thread when function options are used (#18987)

Co-authored-by: Wout Mertens <Wout.Mertens@gmail.com>

Author: sapphi-red

packages/vite/package.json

@@ -145,6 +145,7 @@
     "sirv": "^3.0.0",
     "source-map-support": "^0.5.21",
     "strip-literal": "^2.1.1",
+    "terser": "^5.37.0",
     "tinyglobby": "^0.2.10",
     "tsconfck": "^3.1.4",
     "tslib": "^2.8.1",

packages/vite/src/node/__tests__/plugins/terser.spec.ts

@@ -0,0 +1,55 @@
+import { resolve } from 'node:path'
+import { fileURLToPath } from 'node:url'
+import { describe, expect, test } from 'vitest'
+import { build } from 'vite'
+import type { RollupOutput } from 'rollup'
+import type { TerserOptions } from '../../plugins/terser'
+
+const __dirname = resolve(fileURLToPath(import.meta.url), '..')
+
+describe('terser', () => {
+  const run = async (terserOptions: TerserOptions) => {
+    const result = (await build({
+      root: resolve(__dirname, '../packages/build-project'),
+      logLevel: 'silent',
+      build: {
+        write: false,
+        minify: 'terser',
+        terserOptions,
+      },
+      plugins: [
+        {
+          name: 'test',
+          resolveId(id) {
+            if (id === 'entry.js') {
+              return '\0' + id
+            }
+          },
+          load(id) {
+            if (id === '\0entry.js') {
+              return `const foo = 1;console.log(foo)`
+            }
+          },
+        },
+      ],
+    })) as RollupOutput
+    return result.output[0].code
+  }
+
+  test('basic', async () => {
+    await run({})
+  })
+
+  test('nth', async () => {
+    const resultCode = await run({
+      mangle: {
+        nth_identifier: {
+          get: (n) => {
+            return 'prefix_' + n.toString()
+          },
+        },
+      },
+    })
+    expect(resultCode).toContain('prefix_')
+  })
+})

packages/vite/src/node/plugins/terser.ts

@@ -1,5 +1,5 @@
 import type { Terser } from 'dep-types/terser'
-import { Worker } from 'artichokie'
+import { WorkerWithFallback } from 'artichokie'
 import type { Plugin } from '../plugin'
 import type { ResolvedConfig } from '..'
 import { requireResolveFromRootWithFallback } from '../utils'
@@ -37,7 +37,7 @@ export function terserPlugin(config: ResolvedConfig): Plugin {
   const { maxWorkers, ...terserOptions } = config.build.terserOptions
 
   const makeWorker = () =>
-    new Worker(
+    new WorkerWithFallback(
       () =>
         async (
           terserPath: string,
@@ -50,6 +50,16 @@ export function terserPlugin(config: ResolvedConfig): Plugin {
           return terser.minify(code, options) as Terser.MinifyOutput
         },
       {
+        shouldUseFake(_terserPath, _code, options) {
+          return !!(
+            (typeof options.mangle === 'object' &&
+              (options.mangle.nth_identifier?.get ||
+                (typeof options.mangle.properties === 'object' &&
+                  options.mangle.properties.nth_identifier?.get))) ||
+            typeof options.format?.comments === 'function' ||
+            typeof options.output?.comments === 'function'
+          )
+        },
         max: maxWorkers,
       },
     )