[@vitejs/plugin-legacy] Bundles polyfills-modern even when renderLegacyChunks is false

[DreierF]

Describe the bug

Since version 1.4.0 the @vitejs/plugin-legacy automatically tries to restore the previous behavior of polyfilling dynamic import.
However this currently ignores the value of renderLegacyChunks. When it is set to false only additional polyfills for modern browsers are applied. In this case the plugin should not overwrite the value set via build.polyfillDynamicImport = false and therefore only bundle dynamic import polyfills when the user explicitly set build.polyfillDynamicImport = true.

Cause:

vite/packages/plugin-legacy/index.js

Line 79 in 32c596c

config.build.polyfillDynamicImport = true

Reproduction

export default defineConfig({
	build: {
		target: 'es2017',
		polyfillDynamicImport: false,
		// ...
	},
	plugins: [
		// ...
		legacy({
			modernPolyfills: [
				'es.promise.finally',
				'es.array.flat',
				'es.array.flat-map',
			],
			renderLegacyChunks: false
		}),
		// ...
	],
});

Logs

As you can see in the logs below polyfillDynamicImport is always set to true.

  vite:config bundled config file loaded in 175ms +0ms
  vite:config using resolved config: {
  vite:config   base: './',
  vite:config   optimizeDeps: {
  vite:config     exclude: [ 'ts-closure-library/lib/ui/tree' ],
  vite:config     esbuildOptions: { keepNames: undefined }
  vite:config   },
  vite:config   resolve: {
  vite:config     dedupe: undefined,
  vite:config     alias: [
  vite:config       [Object], [Object],
  vite:config       [Object], [Object],
  vite:config       [Object], [Object],
  vite:config       [Object]
  vite:config     ]
  vite:config   },
  vite:config   build: {
  vite:config     target: 'es2017',
  vite:config     polyfillDynamicImport: true,
  vite:config     outDir: 'build/vite/META-INF/web',
  vite:config     assetsDir: 'assets',
  vite:config     assetsInlineLimit: 4096,
  vite:config     cssCodeSplit: true,
  vite:config     sourcemap: true,
  vite:config     rollupOptions: { external: [Array] },
  vite:config     commonjsOptions: { include: [Array], extensions: [Array] },
  vite:config     minify: 'terser',
  vite:config     terserOptions: {},
  vite:config     cleanCssOptions: {},
  vite:config     write: true,
  vite:config     emptyOutDir: null,
  vite:config     manifest: false,
  vite:config     lib: false,
  vite:config     ssr: false,
  vite:config     ssrManifest: false,
  vite:config     brotliSize: false,
  vite:config     chunkSizeWarningLimit: 500,
  vite:config     watch: null
  vite:config   },
  vite:config   plugins: [
  vite:config     'alias',
  vite:config     'react-refresh',
  vite:config     'vite:tsconfig-paths',
  vite:config     'vite:dynamic-import-polyfill',
  vite:config     'vite:resolve',
  vite:config     'vite:html',
  vite:config     'vite:css',
  vite:config     'vite:esbuild',
  vite:config     'vite:json',
  vite:config     'vite:wasm',
  vite:config     'vite:worker',
  vite:config     'vite:asset',
  vite:config     'legacy-config',
  vite:config     'legacy-generate-polyfill-chunk',
  vite:config     'legacy-env',
  vite:config     'vite:define',
  vite:config     'vite:css-post',
  vite:config     'vite:build-html',
  vite:config     'commonjs',
  vite:config     'vite:data-uri',
  vite:config     'rollup-plugin-dynamic-import-variables',
  vite:config     'legacy-post-process',
  vite:config     'vite:import-analysis',
  vite:config     'vite:esbuild-transpile',
  vite:config     'vite:terser',
  vite:config     'vite:reporter'
  vite:config   ],
  vite:config   server: {
  vite:config     host: '127.0.0.1',
  vite:config     port: 9090,
  vite:config     strictPort: true,
  vite:config     watch: { ignored: [Array] },
  vite:config     fsServe: {
  vite:config       root: '...',
  vite:config       strict: false
  vite:config     }
  vite:config   },
  vite:config   css: {
  vite:config     preprocessorOptions: { less: [Object] },
  vite:config     modules: { localsConvention: 'camelCase' }
  vite:config   },
  vite:config   define: { 'import.meta.env.LEGACY': '__VITE_IS_LEGACY__' },
  vite:config   configFile: '/Users/florian/Documents/CQSE/TeamscaleWebpack/engine/com.teamscale.ui/vite.config.ts',
  vite:config   configFileDependencies: [ 'vite.config.ts' ],
  vite:config   inlineConfig: {
  vite:config     root: undefined,
  vite:config     base: undefined,
  vite:config     mode: undefined,
  vite:config     configFile: undefined,
  vite:config     logLevel: undefined,
  vite:config     clearScreen: undefined,
  vite:config     build: {}
  vite:config   },
  vite:config   root: '/Users/florian/Documents/CQSE/TeamscaleWebpack/engine/com.teamscale.ui',
  vite:config   publicDir: '/Users/florian/Documents/CQSE/TeamscaleWebpack/engine/com.teamscale.ui/public',
  vite:config   cacheDir: '/Users/florian/Documents/CQSE/TeamscaleWebpack/engine/com.teamscale.ui/node_modules/.vite',
  vite:config   command: 'build',
  vite:config   mode: 'production',
  vite:config   isProduction: true,
  vite:config   env: { BASE_URL: './', MODE: 'production', DEV: false, PROD: true },
  vite:config   assetsInclude: [Function: assetsInclude],
  vite:config   logger: {
  vite:config     hasWarned: false,
  vite:config     info: [Function: info],
  vite:config     warn: [Function: warn],
  vite:config     warnOnce: [Function: warnOnce],
  vite:config     error: [Function: error],
  vite:config     clearScreen: [Function: clearScreen]
  vite:config   },
  vite:config   createResolver: [Function: createResolver]
  vite:config } +136ms

[DreierF]

Fixed with #3774