feat: avoid scanner during build and only optimize CJS in SSR

docs/vite.config.ts

@@ -6,5 +6,10 @@ export default defineConfig({
   },
   legacy: {
     buildSsrCjsExternalHeuristics: true
+  },
+  optimizeDeps: {
+    // vitepress is aliased with replacement `join(DIST_CLIENT_PATH, '/index')`
+    // This needs to be excluded from optimization
+    exclude: ['vitepress']
   }
 })

packages/vite/LICENSE.md

@@ -975,7 +975,7 @@ Repository: http://github.com/bripkens/connect-history-api-fallback.git
 
 > The MIT License
 > 
-> Copyright (c) 2012 Ben Ripkens http://bripkens.de
+> Copyright (c) 2022 Ben Blackmore and contributors
 > 
 > Permission is hereby granted, free of charge, to any person obtaining a copy
 > of this software and associated documentation files (the "Software"), to deal

packages/vite/src/node/config.ts

@@ -545,7 +545,9 @@ export async function resolveConfig(
             ]
           }))
       }
-      return (await container.resolveId(id, importer, { ssr }))?.id
+      return (
+        await container.resolveId(id, importer, { ssr, scan: options?.scan })
+      )?.id
     }
   }
 

packages/vite/src/node/optimizer/index.ts

@@ -54,11 +54,7 @@ export type ExportsData = {
 export interface DepsOptimizer {
   metadata: DepOptimizationMetadata
   scanProcessing?: Promise<void>
-  registerMissingImport: (
-    id: string,
-    resolved: string,
-    ssr?: boolean
-  ) => OptimizedDepInfo
+  registerMissingImport: (id: string, resolved: string) => OptimizedDepInfo
   run: () => void
 
   isOptimizedDepFile: (id: string) => boolean
@@ -281,7 +277,7 @@ export async function optimizeServerSsrDeps(
     ) as string[]
     noExternalFilter =
       noExternal === true
-        ? (dep: unknown) => false
+        ? (dep: unknown) => true
         : createFilter(undefined, exclude, {
             resolve: false
           })
@@ -705,16 +701,22 @@ export async function addManuallyIncludedOptimizeDeps(
         )
       }
     }
-    const resolve = config.createResolver({ asSrc: false, scan: true })
+    const resolve = config.createResolver({
+      asSrc: false,
+      scan: true,
+      ssrOptimizeCheck: ssr
+    })
     for (const id of [...optimizeDepsInclude, ...extra]) {
       // normalize 'foo   >bar` as 'foo > bar' to prevent same id being added
       // and for pretty printing
       const normalizedId = normalizeId(id)
       if (!deps[normalizedId] && filter?.(normalizedId) !== false) {
-        const entry = await resolve(id)
+        const entry = await resolve(id, undefined, undefined, ssr)
         if (entry) {
           if (isOptimizable(entry, optimizeDeps)) {
-            deps[normalizedId] = entry
+            if (!entry.endsWith('?__vite_skip_optimization')) {
+              deps[normalizedId] = entry
+            }
           } else {
             unableToOptimize(entry, 'Cannot optimize dependency')
           }

packages/vite/src/node/optimizer/optimizer.ts

@@ -183,11 +183,10 @@ async function createDepsOptimizer(
       newDepsDiscovered = true
     }
 
-    // TODO: We need the scan during build time, until preAliasPlugin
-    // is refactored to work without the scanned deps. We could skip
-    // this for build later.
-
-    runScanner()
+    if (!isBuild) {
+      // Important, the scanner is dev only
+      runScanner()
+    }
   }
 
   async function runScanner() {

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

@@ -1,6 +1,14 @@
-import type { Alias, AliasOptions, ResolvedConfig } from '..'
+import fs from 'node:fs'
+import path from 'node:path'
+import type {
+  Alias,
+  AliasOptions,
+  DepOptimizationOptions,
+  ResolvedConfig
+} from '..'
 import type { Plugin } from '../plugin'
-import { bareImportRE } from '../utils'
+import { createIsConfiguredAsSsrExternal } from '../ssr/ssrExternal'
+import { bareImportRE, isOptimizable, moduleListContains } from '../utils'
 import { getDepsOptimizer } from '../optimizer'
 import { tryOptimizedResolve } from './resolve'
 
@@ -9,6 +17,8 @@ import { tryOptimizedResolve } from './resolve'
  */
 export function preAliasPlugin(config: ResolvedConfig): Plugin {
   const findPatterns = getAliasPatterns(config.resolve.alias)
+  const isConfiguredAsExternal = createIsConfiguredAsSsrExternal(config)
+  const isBuild = config.command === 'build'
   return {
     name: 'vite:pre-alias',
     async resolveId(id, importer, options) {
@@ -18,16 +28,70 @@ export function preAliasPlugin(config: ResolvedConfig): Plugin {
         importer &&
         depsOptimizer &&
         bareImportRE.test(id) &&
-        !options?.scan
+        !options?.scan &&
+        id !== '@vite/client' &&
+        id !== '@vite/env'
       ) {
         if (findPatterns.find((pattern) => matches(pattern, id))) {
-          return await tryOptimizedResolve(depsOptimizer, id, importer)
+          const optimizedId = await tryOptimizedResolve(
+            depsOptimizer,
+            id,
+            importer
+          )
+          if (optimizedId) {
+            return optimizedId // aliased dep already optimized
+          }
+
+          const resolved = await this.resolve(id, importer, {
+            skipSelf: true,
+            ...options
+          })
+          if (resolved && !depsOptimizer.isOptimizedDepFile(resolved.id)) {
+            const optimizeDeps = depsOptimizer.options
+            const resolvedId = resolved.id
+            const isVirtual = resolvedId === id || resolvedId.includes('\0')
+            if (
+              !isVirtual &&
+              fs.existsSync(resolvedId) &&
+              !moduleListContains(optimizeDeps.exclude, id) &&
+              path.isAbsolute(resolvedId) &&
+              (resolvedId.includes('node_modules') ||
+                optimizeDeps.include?.includes(id)) &&
+              isOptimizable(resolvedId, optimizeDeps) &&
+              !(isBuild && ssr && isConfiguredAsExternal(id)) &&
+              (!ssr || optimizeAliasReplacementForSSR(resolvedId, optimizeDeps))
+            ) {
+              // aliased dep has not yet been optimized
+              const optimizedInfo = depsOptimizer!.registerMissingImport(
+                id,
+                resolvedId
+              )
+              return { id: depsOptimizer!.getOptimizedDepId(optimizedInfo) }
+            }
+          }
+          return resolved
         }
       }
     }
   }
 }
 
+function optimizeAliasReplacementForSSR(
+  id: string,
+  optimizeDeps: DepOptimizationOptions
+) {
+  if (optimizeDeps.include?.includes(id)) {
+    return true
+  }
+  // In the regular resolution, the default for non-external modules is to
+  // be optimized if they are CJS. Here, we don't have the package id but
+  // only the replacement file path. We could find the package.json from
+  // the id and respect the same default in the future.
+  // Default to not optimize an aliased replacement for now, forcing the
+  // user to explicitly add it to the ssr.optimizeDeps.include list.
+  return false
+}
+
 // In sync with rollup plugin alias logic
 function matches(pattern: string | RegExp, importee: string) {
   if (pattern instanceof RegExp) {

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

@@ -82,6 +82,8 @@ export interface InternalResolveOptions extends ResolveOptions {
   tryEsmOnly?: boolean
   // True when resolving during the scan phase to discover dependencies
   scan?: boolean
+  // Appends ?__vite_skip_optimization to the resolved id if shouldn't be optimized
+  ssrOptimizeCheck?: boolean
   // Resolve using esbuild deps optimization
   getDepsOptimizer?: (ssr: boolean) => DepsOptimizer | undefined
   shouldExternalize?: (id: string) => boolean | undefined
@@ -665,41 +667,66 @@ export function tryNodeResolve(
     })
   }
 
+  const ext = path.extname(resolved)
+  const isCJS = ext === '.cjs' || (ext === '.js' && pkg.data.type !== 'module')
+
   if (
-    !resolved.includes('node_modules') || // linked
-    !depsOptimizer || // resolving before listening to the server
-    options.scan // initial esbuild scan phase
+    !options.ssrOptimizeCheck &&
+    (!resolved.includes('node_modules') || // linked
+      !depsOptimizer || // resolving before listening to the server
+      options.scan) // initial esbuild scan phase
   ) {
     return { id: resolved }
   }
+
   // if we reach here, it's a valid dep import that hasn't been optimized.
   const isJsType = OPTIMIZABLE_ENTRY_RE.test(resolved)
 
-  const exclude = depsOptimizer.options.exclude
-  if (
+  let exclude = depsOptimizer?.options.exclude
+  let include = depsOptimizer?.options.exclude
+  if (options.ssrOptimizeCheck) {
+    // we don't have the depsOptimizer
+    exclude = options.ssrConfig?.optimizeDeps?.exclude
+    include = options.ssrConfig?.optimizeDeps?.exclude
+  }
+
+  const skipOptimization =
     !isJsType ||
     importer?.includes('node_modules') ||
     exclude?.includes(pkgId) ||
     exclude?.includes(nestedPath) ||
     SPECIAL_QUERY_RE.test(resolved) ||
-    (!isBuild && ssr)
-  ) {
+    (!isBuild && ssr) ||
+    // Only optimize non-external CJS deps during SSR by default
+    (ssr &&
+      !isCJS &&
+      !(include?.includes(pkgId) || include?.includes(nestedPath)))
+
+  if (options.ssrOptimizeCheck) {
+    return {
+      id: skipOptimization
+        ? injectQuery(resolved, `__vite_skip_optimization`)
+        : resolved
+    }
+  }
+
+  if (skipOptimization) {
     // excluded from optimization
     // Inject a version query to npm deps so that the browser
     // can cache it without re-validation, but only do so for known js types.
     // otherwise we may introduce duplicated modules for externalized files
     // from pre-bundled deps.
     if (!isBuild) {
-      const versionHash = depsOptimizer.metadata.browserHash
+      const versionHash = depsOptimizer!.metadata.browserHash
       if (versionHash && isJsType) {
         resolved = injectQuery(resolved, `v=${versionHash}`)
       }
     }
   } else {
     // this is a missing import, queue optimize-deps re-run and
     // get a resolved its optimized info
-    const optimizedInfo = depsOptimizer.registerMissingImport(id, resolved, ssr)
-    resolved = depsOptimizer.getOptimizedDepId(optimizedInfo)
+    const optimizedInfo = depsOptimizer!.registerMissingImport(id, resolved)
+    resolved = depsOptimizer!.getOptimizedDepId(optimizedInfo)
   }
 
   if (isBuild) {

packages/vite/src/node/ssr/ssrExternal.ts

@@ -105,20 +105,17 @@ export function shouldExternalizeForSSR(
   return isSsrExternal(id)
 }
 
-function createIsSsrExternal(
+export function createIsConfiguredAsSsrExternal(
   config: ResolvedConfig
-): (id: string) => boolean | undefined {
-  const processedIds = new Map<string, boolean | undefined>()
-
-  const { ssr, root } = config
-
+): (id: string) => boolean {
+  const { ssr } = config
   const noExternal = ssr?.noExternal
   const noExternalFilter =
     noExternal !== 'undefined' &&
     typeof noExternal !== 'boolean' &&
     createFilter(undefined, noExternal, { resolve: false })
 
-  const isConfiguredAsExternal = (id: string) => {
+  return (id: string) => {
     const { ssr } = config
     if (!ssr || ssr.external?.includes(id)) {
       return true
@@ -131,6 +128,16 @@ function createIsSsrExternal(
     }
     return true
   }
+}
+
+function createIsSsrExternal(
+  config: ResolvedConfig
+): (id: string) => boolean | undefined {
+  const processedIds = new Map<string, boolean | undefined>()
+
+  const { ssr, root } = config
+
+  const isConfiguredAsExternal = createIsConfiguredAsSsrExternal(config)
 
   const resolveOptions: InternalResolveOptions = {
     root,