refactor: introduce mergeWithDefaults and organize how default values for config options are set

packages/vite/src/node/__tests__/utils.spec.ts

@@ -10,6 +10,7 @@ import {
   getLocalhostAddressIfDiffersFromDNS,
   injectQuery,
   isFileReadable,
+  mergeWithDefaults,
   posToNumber,
   processSrcSetSync,
   resolveHostname,
@@ -449,3 +450,37 @@ describe('flattenId', () => {
     expect(result2).toHaveLength(170)
   })
 })
+
+describe('mergeWithDefaults', () => {
+  test('merges with defaults', () => {
+    const actual = mergeWithDefaults(
+      {
+        useDefault: 1,
+        useValueIfNull: 2,
+        replaceArray: [0, 1],
+        nested: {
+          foo: 'bar',
+        },
+      },
+      {
+        useDefault: undefined,
+        useValueIfNull: null,
+        useValueIfNoDefault: 'foo',
+        replaceArray: [2, 3],
+        nested: {
+          foo2: 'bar2',
+        },
+      },
+    )
+    expect(actual).toEqual({
+      useDefault: 1,
+      useValueIfNull: null,
+      useValueIfNoDefault: 'foo',
+      replaceArray: [2, 3],
+      nested: {
+        foo: 'bar',
+        foo2: 'bar2',
+      },
+    })
+  })
+})

packages/vite/src/node/__tests_dts__/utils.ts

@@ -0,0 +1,58 @@
+/* eslint-disable @typescript-eslint/no-unused-vars */
+import type { Equal, ExpectTrue } from '@type-challenges/utils'
+import { mergeWithDefaults } from '../utils'
+
+const useDefaultTypeForUndefined1 = mergeWithDefaults(
+  {
+    foo: 1,
+  },
+  {},
+)
+
+const useDefaultTypeForUndefined2 = mergeWithDefaults(
+  {
+    foo: 1,
+  },
+  {
+    foo: 2 as number | undefined,
+  },
+)
+
+const includeKeyNotIncludedInDefault1 = mergeWithDefaults(
+  {},
+  {
+    foo: 2,
+  },
+)
+
+const extendTypeWithValueType = mergeWithDefaults(
+  {
+    foo: 1,
+  },
+  {
+    foo: 'string' as string | number,
+  },
+)
+
+const plainObject = mergeWithDefaults({ foo: { bar: 1 } }, { foo: { baz: 2 } })
+
+const nonPlainObject = mergeWithDefaults(
+  { foo: ['foo'] },
+  { foo: [0] as number[] | undefined },
+)
+
+const optionalNested = mergeWithDefaults({ foo: { bar: true } }, {
+  foo: { bar: false },
+} as { foo?: { bar?: boolean } })
+
+export type cases1 = [
+  ExpectTrue<Equal<typeof useDefaultTypeForUndefined1, { foo: number }>>,
+  ExpectTrue<Equal<typeof useDefaultTypeForUndefined2, { foo: number }>>,
+  ExpectTrue<Equal<typeof includeKeyNotIncludedInDefault1, { foo: number }>>,
+  ExpectTrue<Equal<typeof extendTypeWithValueType, { foo: string | number }>>,
+  ExpectTrue<Equal<typeof plainObject, { foo: { bar: number; baz: number } }>>,
+  ExpectTrue<Equal<typeof nonPlainObject, { foo: string[] | number[] }>>,
+  ExpectTrue<
+    Equal<typeof optionalNested, { foo: { bar: boolean } | { bar: boolean } }>
+  >,
+]

packages/vite/src/node/build.ts

@@ -33,7 +33,7 @@ import type {
   ResolvedConfig,
   ResolvedEnvironmentOptions,
 } from './config'
-import { resolveConfig } from './config'
+import { configDefaults, resolveConfig } from './config'
 import type { PartialEnvironment } from './baseEnvironment'
 import { buildReporterPlugin } from './plugins/reporter'
 import { buildEsbuildPlugin } from './plugins/esbuild'
@@ -46,6 +46,7 @@ import {
   emptyDir,
   getPkgName,
   joinUrlSegments,
+  mergeWithDefaults,
   normalizePath,
   partialEncodeURIPath,
 } from './utils'
@@ -344,6 +345,44 @@ export interface ResolvedBuildOptions
   modulePreload: false | ResolvedModulePreloadOptions
 }
 
+export const buildEnvironmentOptionsDefaults = Object.freeze({
+  target: 'modules',
+  /** @deprecated */
+  polyfillModulePreload: true,
+  modulePreload: true,
+  outDir: 'dist',
+  assetsDir: 'assets',
+  assetsInlineLimit: DEFAULT_ASSETS_INLINE_LIMIT,
+  cssCodeSplit: true,
+  // cssTarget
+  // cssMinify
+  sourcemap: false,
+  minify: 'esbuild',
+  terserOptions: {},
+  rollupOptions: {},
+  commonjsOptions: {
+    include: [/node_modules/],
+    extensions: ['.js', '.cjs'],
+  },
+  dynamicImportVarsOptions: {
+    warnOnError: true,
+    exclude: [/node_modules/],
+  },
+  write: true,
+  emptyOutDir: true,
+  copyPublicDir: true,
+  manifest: false,
+  lib: false,
+  ssr: false,
+  ssrManifest: false,
+  ssrEmitAssets: false,
+  // emitAssets
+  reportCompressedSize: true,
+  chunkSizeWarningLimit: 500,
+  watch: null,
+  // createEnvironment
+})
+
 export function resolveBuildEnvironmentOptions(
   raw: BuildEnvironmentOptions,
   logger: Logger,
@@ -366,84 +405,49 @@ export function resolveBuildEnvironmentOptions(
     raw.modulePreload = { polyfill: false }
   }
 
-  const modulePreload = raw.modulePreload
-  const defaultModulePreload = {
-    polyfill: true,
+  const merged = mergeWithDefaults(
+    {
+      ...buildEnvironmentOptionsDefaults,
+      cssCodeSplit: !raw.lib,
+      minify: consumer === 'server' ? false : 'esbuild',
+      ssr: consumer === 'server',
+      emitAssets: consumer === 'client',
+      createEnvironment: (name, config) => new BuildEnvironment(name, config),
+    } satisfies BuildEnvironmentOptions,
+    raw,
+  )
+
+  // handle special build targets
+  if (merged.target === 'modules') {
+    merged.target = ESBUILD_MODULES_TARGET
   }
 
-  const defaultBuildEnvironmentOptions: BuildEnvironmentOptions = {
-    outDir: 'dist',
-    assetsDir: 'assets',
-    assetsInlineLimit: DEFAULT_ASSETS_INLINE_LIMIT,
-    cssCodeSplit: !raw.lib,
-    sourcemap: false,
-    rollupOptions: {},
-    minify: consumer === 'server' ? false : 'esbuild',
-    terserOptions: {},
-    write: true,
-    emptyOutDir: null,
-    copyPublicDir: true,
-    manifest: false,
-    lib: false,
-    ssr: consumer === 'server',
-    ssrManifest: false,
-    ssrEmitAssets: false,
-    emitAssets: consumer === 'client',
-    reportCompressedSize: true,
-    chunkSizeWarningLimit: 500,
-    watch: null,
-    createEnvironment: (name, config) => new BuildEnvironment(name, config),
+  // normalize false string into actual false
+  if ((merged.minify as string) === 'false') {
+    merged.minify = false
+  } else if (merged.minify === true) {
+    merged.minify = 'esbuild'
   }
 
-  const userBuildEnvironmentOptions = raw
-    ? mergeConfig(defaultBuildEnvironmentOptions, raw)
-    : defaultBuildEnvironmentOptions
+  const defaultModulePreload = {
+    polyfill: true,
+  }
 
-  // @ts-expect-error Fallback options instead of merging
   const resolved: ResolvedBuildEnvironmentOptions = {
-    target: 'modules',
-    cssTarget: false,
-    ...userBuildEnvironmentOptions,
-    commonjsOptions: {
-      include: [/node_modules/],
-      extensions: ['.js', '.cjs'],
-      ...userBuildEnvironmentOptions.commonjsOptions,
-    },
-    dynamicImportVarsOptions: {
-      warnOnError: true,
-      exclude: [/node_modules/],
-      ...userBuildEnvironmentOptions.dynamicImportVarsOptions,
-    },
+    ...merged,
+    cssTarget: merged.cssTarget ?? merged.target,
+    cssMinify:
+      merged.cssMinify ?? (consumer === 'server' ? 'esbuild' : !!merged.minify),
     // Resolve to false | object
     modulePreload:
-      modulePreload === false
+      merged.modulePreload === false
         ? false
-        : typeof modulePreload === 'object'
-          ? {
+        : merged.modulePreload === true
+          ? defaultModulePreload
+          : {
               ...defaultModulePreload,
-              ...modulePreload,
-            }
-          : defaultModulePreload,
-  }
-
-  // handle special build targets
-  if (resolved.target === 'modules') {
-    resolved.target = ESBUILD_MODULES_TARGET
-  }
-
-  if (!resolved.cssTarget) {
-    resolved.cssTarget = resolved.target
-  }
-
-  // normalize false string into actual false
-  if ((resolved.minify as string) === 'false') {
-    resolved.minify = false
-  } else if (resolved.minify === true) {
-    resolved.minify = 'esbuild'
-  }
-
-  if (resolved.cssMinify == null) {
-    resolved.cssMinify = consumer === 'server' ? 'esbuild' : !!resolved.minify
+              ...merged.modulePreload,
+            },
   }
 
   if (isSsrTargetWebworkerEnvironment) {
@@ -1504,11 +1508,10 @@ export function resolveBuilderOptions(
   options: BuilderOptions | undefined,
 ): ResolvedBuilderOptions | undefined {
   if (!options) return
-  return {
-    sharedConfigBuild: options.sharedConfigBuild ?? false,
-    sharedPlugins: options.sharedPlugins ?? false,
-    buildApp: options.buildApp ?? defaultBuildApp,
-  }
+  return mergeWithDefaults(
+    { ...configDefaults.builder, buildApp: defaultBuildApp },
+    options,
+  )
 }
 
 export type ResolvedBuilderOptions = Required<BuilderOptions>