fix: consider # as a valid dir symbol (fix #4701)

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

@@ -89,3 +89,9 @@ test('resolve.mainFields', async () => {
 test('resolve.conditions', async () => {
   expect(await page.textContent('.custom-condition')).toMatch('[success]')
 })
+
+test('resolve package that contains # in path', async () => {
+  expect(await page.textContent('.path-contains-sharp-symbol')).toMatch(
+    '[success]'
+  )
+})

packages/playground/resolve/index.html

@@ -60,6 +60,9 @@ <h2>resolve.mainFields</h2>
 <h2>resolve.conditions</h2>
 <p class="custom-condition"></p>
 
+<h2>resolve package that contains # in path</h2>
+<p class="path-contains-sharp-symbol"></p>
+
 <script type="module">
   function text(selector, text) {
     document.querySelector(selector).textContent = text
@@ -171,6 +174,9 @@ <h2>resolve.conditions</h2>
 
   import { msg as inlineMsg } from './inline-package'
   text('.inline-pkg', inlineMsg)
+
+  import es5Ext from 'es5-ext'
+  text('.path-contains-sharp-symbol', '[success]')
 </script>
 
 <style>

packages/playground/resolve/package.json

@@ -16,6 +16,7 @@
     "resolve-custom-condition": "link:./custom-condition",
     "@babel/runtime": "^7.12.5",
     "normalize.css": "^8.0.1",
+    "es5-ext": "0.10.53",
     "resolve-linked": "workspace:*"
   }
 }

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

@@ -10,7 +10,8 @@ export function loadFallbackPlugin(): Plugin {
     name: 'vite:load-fallback',
     async load(id) {
       try {
-        return fs.readFile(cleanUrl(id), 'utf-8')
+        // if we don't add `await` here, we couldn't catch the error in readFile
+        return await fs.readFile(cleanUrl(id), 'utf-8')
       } catch (e) {
         return fs.readFile(id, 'utf-8')
       }

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

@@ -314,6 +314,24 @@ function tryFsResolve(
   }
 
   let res: string | undefined
+
+  // if we fould postfix exist, we should first try resolving file with postfix. details see #4703.
+  if (
+    postfix &&
+    (res = tryResolveFile(
+      fsPath,
+      '',
+      options,
+      false,
+      targetWeb,
+      preserveSymlinks,
+      options.tryPrefix,
+      options.skipPackageJson
+    ))
+  ) {
+    return res
+  }
+
   if (
     (res = tryResolveFile(
       file,
@@ -330,6 +348,22 @@ function tryFsResolve(
   }
 
   for (const ext of options.extensions || DEFAULT_EXTENSIONS) {
+    if (
+      postfix &&
+      (res = tryResolveFile(
+        fsPath + ext,
+        '',
+        options,
+        false,
+        targetWeb,
+        preserveSymlinks,
+        options.tryPrefix,
+        options.skipPackageJson
+      ))
+    ) {
+      return res
+    }
+
     if (
       (res = tryResolveFile(
         file + ext,
@@ -346,6 +380,22 @@ function tryFsResolve(
     }
   }
 
+  if (
+    postfix &&
+    (res = tryResolveFile(
+      fsPath,
+      '',
+      options,
+      tryIndex,
+      targetWeb,
+      preserveSymlinks,
+      options.tryPrefix,
+      options.skipPackageJson
+    ))
+  ) {
+    return res
+  }
+
   if (
     (res = tryResolveFile(
       file,