feat: support async plugins

docs/config/shared-options.md

@@ -77,9 +77,9 @@ const obj = {
 
 ## plugins
 
-- **Type:** `(Plugin | Plugin[])[]`
+- **Type:** `(Plugin | Plugin[] | Promise<Plugin | Plugin[]>)[]`
 
-Array of plugins to use. Falsy plugins are ignored and arrays of plugins are flattened. See [Plugin API](/guide/api-plugin) for more details on Vite plugins.
+Array of plugins to use. Falsy plugins are ignored and arrays of plugins are flattened. If a promise is returned, it would be resolved before running. See [Plugin API](/guide/api-plugin) for more details on Vite plugins.
 
 ## publicDir
 

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

@@ -1,5 +1,6 @@
 import { describe, expect, test } from 'vitest'
 import {
+  asyncFlatten,
   getHash,
   getPotentialTsSrcPaths,
   injectQuery,
@@ -106,3 +107,40 @@ describe('getHash', () => {
     expect(hash).toMatch(/^[\da-f]{8}$/)
   })
 })
+
+describe('asyncFlatten', () => {
+  test('plain array', async () => {
+    const arr = await asyncFlatten([1, 2, 3])
+    expect(arr).toEqual([1, 2, 3])
+  })
+
+  test('nested array', async () => {
+    const arr = await asyncFlatten([1, 2, 3, [4, 5, 6]])
+    expect(arr).toEqual([1, 2, 3, 4, 5, 6])
+  })
+
+  test('plain promise array', async () => {
+    const arr = await asyncFlatten([1, 2, Promise.resolve(3)])
+    expect(arr).toEqual([1, 2, 3])
+  })
+
+  test('nested promise array', async () => {
+    const arr = await asyncFlatten([
+      1,
+      2,
+      Promise.resolve(3),
+      Promise.resolve([4, 5, 6])
+    ])
+    expect(arr).toEqual([1, 2, 3, 4, 5, 6])
+  })
+
+  test('2x nested promise array', async () => {
+    const arr = await asyncFlatten([
+      1,
+      2,
+      Promise.resolve(3),
+      Promise.resolve([4, 5, Promise.resolve(6), Promise.resolve([7, 8, 9])])
+    ])
+    expect(arr).toEqual([1, 2, 3, 4, 5, 6, 7, 8, 9])
+  })
+})

packages/vite/src/node/config.ts

@@ -17,6 +17,7 @@ import type { PreviewOptions, ResolvedPreviewOptions } from './preview'
 import { resolvePreviewOptions } from './preview'
 import type { CSSOptions } from './plugins/css'
 import {
+  asyncFlatten,
   createDebugger,
   createFilter,
   dynamicImport,
@@ -66,7 +67,13 @@ export function defineConfig(config: UserConfigExport): UserConfigExport {
   return config
 }
 
-export type PluginOption = Plugin | false | null | undefined | PluginOption[]
+export type PluginOption =
+  | Plugin
+  | Promise<Plugin>
+  | false
+  | null
+  | undefined
+  | PluginOption[]
 
 export interface UserConfig {
   /**
@@ -330,17 +337,19 @@ export async function resolveConfig(
   configEnv.mode = mode
 
   // resolve plugins
-  const rawUserPlugins = (config.plugins || []).flat(Infinity).filter((p) => {
-    if (!p) {
-      return false
-    } else if (!p.apply) {
-      return true
-    } else if (typeof p.apply === 'function') {
-      return p.apply({ ...config, mode }, configEnv)
-    } else {
-      return p.apply === command
+  const rawUserPlugins = (await asyncFlatten(config.plugins || [])).filter(
+    (p: any) => {
+      if (!p) {
+        return false
+      } else if (!p.apply) {
+        return true
+      } else if (typeof p.apply === 'function') {
+        return p.apply({ ...config, mode }, configEnv)
+      } else {
+        return p.apply === command
+      }
     }
-  }) as Plugin[]
+  ) as Plugin[]
   const [prePlugins, normalPlugins, postPlugins] =
     sortUserPlugins(rawUserPlugins)
 

packages/vite/src/node/utils.ts

@@ -1018,3 +1018,10 @@ export function transformResult(
     map: needSourceMap ? s.generateMap({ hires: true, source: id }) : null
   }
 }
+
+export async function asyncFlatten<T>(arr: T[]): Promise<T[]> {
+  do {
+    arr = (await Promise.all(arr)).flat(Infinity) as any
+  } while (arr.some((v: any) => !!v.then))
+  return arr
+}