feat: support resolveId returning arbitrary value

packages/playground/resolve/__tests__/resolve.spec.ts

@@ -29,3 +29,7 @@ test('css entry', async () => {
 test('monorepo linked dep', async () => {
   expect(await page.textContent('.monorepo')).toMatch('[success]')
 })
+
+test('plugin resolved virutal file', async () => {
+  expect(await page.textContent('.virtual')).toMatch('[success]')
+})

packages/playground/resolve/index.html

@@ -24,6 +24,9 @@ <h2>CSS Entry</h2>
 <h2>Monorepo linked dep</h2>
 <p class="monorepo"></p>
 
+<h2>Plugin resolved virtual file</h2>
+<p class="virtual"></p>
+
 <script type="module">
   function text(selector, text) {
     document.querySelector(selector).textContent = text
@@ -72,4 +75,7 @@ <h2>Monorepo linked dep</h2>
   // monorepo linked dep w/ upper directory import
   import { msg as linkedMsg } from 'resolve-linked'
   text('.monorepo', linkedMsg)
+
+  import { msg as virtualMsg } from '@virtual-file'
+  text('.virtual', virtualMsg)
 </script>

packages/playground/resolve/vite.config.js

@@ -0,0 +1,19 @@
+const virtualFile = '@virtual-file'
+
+module.exports = {
+  plugins: [
+    {
+      name: 'custom-resolve',
+      resolveId(id) {
+        if (id === virtualFile) {
+          return id
+        }
+      },
+      load(id) {
+        if (id === virtualFile) {
+          return `export const msg = "[success] from virtual file"`
+        }
+      }
+    }
+  ]
+}

packages/vite/src/node/constants.ts

@@ -9,6 +9,11 @@ export const DEP_CACHE_DIR = `.vite`
  */
 export const FS_PREFIX = `/@fs/`
 
+/**
+ * Prefix for resolved Ids that are not valid browser import specifiers
+ */
+export const VALID_ID_PREFIX = `/@id/`
+
 export const CLIENT_PUBLIC_PATH = `/@vite/client`
 // eslint-disable-next-line
 export const CLIENT_ENTRY = require.resolve('vite/dist/client/client.js')

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

@@ -23,7 +23,12 @@ import {
   handlePrunedModules,
   lexAcceptedHmrDeps
 } from '../server/hmr'
-import { FS_PREFIX, CLIENT_PUBLIC_PATH, DEP_VERSION_RE } from '../constants'
+import {
+  FS_PREFIX,
+  CLIENT_PUBLIC_PATH,
+  DEP_VERSION_RE,
+  VALID_ID_PREFIX
+} from '../constants'
 import { ViteDevServer } from '../'
 import { checkPublicFile } from './asset'
 import { parse as parseJS } from 'acorn'
@@ -236,6 +241,13 @@ export function importAnalysisPlugin(config: ResolvedConfig): Plugin {
             }
           }
 
+          // if the resolved id is not a valid browser import specifier,
+          // prefix it to make it valid. We will strip this before feeding it
+          // back into the transform pipeline
+          if (!url.startsWith('.') && !url.startsWith('/')) {
+            url = VALID_ID_PREFIX + resolved.id
+          }
+
           // for relative imports, inherit importer's version query
           if (isRelative) {
             const versionMatch = importer.match(DEP_VERSION_RE)

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

@@ -48,10 +48,9 @@ export function resolvePlugin(
 
     resolveId(id, importer) {
       let res
+
+      // explicit fs paths that starts with /@fs/*
       if (asSrc && id.startsWith(FS_PREFIX)) {
-        // explicit fs paths that starts with /@fs/*
-        // these are injected by the rewrite plugin so that the file can work
-        // in the browser
         let fsPath = id.slice(FS_PREFIX.length - 1)
         if (fsPath.startsWith('//')) fsPath = fsPath.slice(1)
         res = tryFsResolve(fsPath, false)
@@ -181,56 +180,56 @@ export function tryNodeResolve(
   const pkgId = deepMatch ? deepMatch[1] || deepMatch[2] : id
   const pkg = resolvePackageData(pkgId, basedir)
 
-  if (pkg) {
-    // prevent deep imports to optimized deps.
-    if (
-      deepMatch &&
-      server &&
-      server.optimizeDepsMetadata &&
-      pkg.data.name in server.optimizeDepsMetadata.map
-    ) {
-      throw new Error(
-        chalk.yellow(
-          `Deep import "${chalk.cyan(
-            id
-          )}" should be avoided because dependency "${chalk.cyan(
-            pkg.data.name
-          )}" has been pre-optimized. Prefer importing directly from the module entry:\n\n` +
-            `${chalk.green(`import { ... } from "${pkg.data.name}"`)}\n\n` +
-            `If the used import is not exported from the package's main entry ` +
-            `and can only be attained via deep import, you can explicitly add ` +
-            `the deep import path to "optimizeDeps.include" in vite.config.js.`
-        )
+  if (!pkg) {
+    return
+  }
+
+  // prevent deep imports to optimized deps.
+  if (
+    deepMatch &&
+    server &&
+    server.optimizeDepsMetadata &&
+    pkg.data.name in server.optimizeDepsMetadata.map
+  ) {
+    throw new Error(
+      chalk.yellow(
+        `Deep import "${chalk.cyan(
+          id
+        )}" should be avoided because dependency "${chalk.cyan(
+          pkg.data.name
+        )}" has been pre-optimized. Prefer importing directly from the module entry:\n\n` +
+          `${chalk.green(`import { ... } from "${pkg.data.name}"`)}\n\n` +
+          `If the used import is not exported from the package's main entry ` +
+          `and can only be attained via deep import, you can explicitly add ` +
+          `the deep import path to "optimizeDeps.include" in vite.config.js.`
       )
-    }
+    )
+  }
 
-    let resolved = deepMatch
-      ? resolveDeepImport(id, pkg)
-      : resolvePackageEntry(id, pkg)
-    if (!resolved) {
-      return
-    }
-    // link id to pkg for browser field mapping check
-    idToPkgMap.set(resolved, pkg)
-    if (isBuild) {
-      // Resolve package side effects for build so that rollup can better
-      // perform tree-shaking
-      return {
-        id: resolved,
-        moduleSideEffects: pkg.hasSideEffects(resolved)
-      }
-    } else {
-      // During serve, inject a version query to npm deps so that the browser
-      // can cache it without revalidation. Make sure to apply this only to
-      // files actually inside node_modules so that locally linked packages
-      // in monorepos are not cached this way.
-      if (resolved.includes('node_modules')) {
-        resolved = injectQuery(resolved, `v=${pkg.data.version}`)
-      }
-      return { id: resolved }
+  let resolved = deepMatch
+    ? resolveDeepImport(id, pkg)
+    : resolvePackageEntry(id, pkg)
+  if (!resolved) {
+    return
+  }
+  // link id to pkg for browser field mapping check
+  idToPkgMap.set(resolved, pkg)
+  if (isBuild) {
+    // Resolve package side effects for build so that rollup can better
+    // perform tree-shaking
+    return {
+      id: resolved,
+      moduleSideEffects: pkg.hasSideEffects(resolved)
     }
   } else {
-    throw new Error(`Failed to resolve package.json for module "${id}"`)
+    // During serve, inject a version query to npm deps so that the browser
+    // can cache it without revalidation. Make sure to apply this only to
+    // files actually inside node_modules so that locally linked packages
+    // in monorepos are not cached this way.
+    if (resolved.includes('node_modules')) {
+      resolved = injectQuery(resolved, `v=${pkg.data.version}`)
+    }
+    return { id: resolved }
   }
 }
 

packages/vite/src/node/server/middlewares/transform.ts

@@ -15,7 +15,7 @@ import { send } from '../send'
 import { transformRequest } from '../transformRequest'
 import { isHTMLProxy } from '../../plugins/html'
 import chalk from 'chalk'
-import { DEP_CACHE_DIR, DEP_VERSION_RE } from '../../constants'
+import { DEP_CACHE_DIR, DEP_VERSION_RE, VALID_ID_PREFIX } from '../../constants'
 
 const debugCache = createDebugger('vite:cache')
 const isDebug = !!process.env.DEBUG
@@ -79,6 +79,12 @@ export function transformMiddleware(
         // strip ?import
         url = removeImportQuery(url)
 
+        // Strip valid id prefix. This is preprended to resolved Ids that are
+        // not valid browser import specifiers by the importAnalysis plugin.
+        if (url.startsWith(VALID_ID_PREFIX)) {
+          url = url.slice(VALID_ID_PREFIX.length)
+        }
+
         // for CSS, we need to differentiate between normal CSS requests and
         // imports
         if (isCSSRequest(url) && req.headers.accept?.includes('text/css')) {