From 724aa8a5fcb0ccaea283b3bf065d29ebf2cdf5a2 Mon Sep 17 00:00:00 2001
From: Evan You <yyx990803@gmail.com>
Date: Tue, 5 Jan 2021 15:21:33 -0500
Subject: [PATCH] fix(resolve): handle exports field w/ mapped directory

---
 .../resolve/__tests__/resolve.spec.ts         | 12 +++++++++
 .../resolve/conditional-exports/dir/dir.js    |  1 +
 .../resolve/conditional-exports/package.json  |  7 +++++-
 packages/playground/resolve/index.html        | 14 +++++++++++
 packages/vite/src/node/plugins/resolve.ts     | 25 +++++++++++++------
 5 files changed, 51 insertions(+), 8 deletions(-)
 create mode 100644 packages/playground/resolve/conditional-exports/dir/dir.js

diff --git a/packages/playground/resolve/__tests__/resolve.spec.ts b/packages/playground/resolve/__tests__/resolve.spec.ts
index f82df05c492656..5a1ca2ed1fa8de 100644
--- a/packages/playground/resolve/__tests__/resolve.spec.ts
+++ b/packages/playground/resolve/__tests__/resolve.spec.ts
@@ -10,6 +10,18 @@ test('deep import with exports field', async () => {
   expect(await page.textContent('.exports-deep')).toMatch('[success]')
 })
 
+test('deep import with exports field + exposed dir', async () => {
+  expect(await page.textContent('.exports-deep-exposed-dir')).toMatch(
+    '[success]'
+  )
+})
+
+test('deep import with exports field + mapped dir', async () => {
+  expect(await page.textContent('.exports-deep-mapped-dir')).toMatch(
+    '[success]'
+  )
+})
+
 test('omitted index/*', async () => {
   expect(await page.textContent('.index')).toMatch('[success]')
 })
diff --git a/packages/playground/resolve/conditional-exports/dir/dir.js b/packages/playground/resolve/conditional-exports/dir/dir.js
new file mode 100644
index 00000000000000..2ee34ebc611afb
--- /dev/null
+++ b/packages/playground/resolve/conditional-exports/dir/dir.js
@@ -0,0 +1 @@
+export const msg = '[success] mapped directory from exports'
diff --git a/packages/playground/resolve/conditional-exports/package.json b/packages/playground/resolve/conditional-exports/package.json
index 60f270c0ddd57b..e98a2c6f8fc72d 100644
--- a/packages/playground/resolve/conditional-exports/package.json
+++ b/packages/playground/resolve/conditional-exports/package.json
@@ -6,6 +6,11 @@
       "import": "./main.js",
       "require": "./cjs.js"
     },
-    "./deep.js": "./deep.js"
+    "./deep.js": "./deep.js",
+    "./dir/": "./dir/",
+    "./dir-mapped/": {
+      "import": "./dir/",
+      "require": "./dir-cjs/"
+    }
   }
 }
diff --git a/packages/playground/resolve/index.html b/packages/playground/resolve/index.html
index 7e679e071a666c..90d8e52b090221 100644
--- a/packages/playground/resolve/index.html
+++ b/packages/playground/resolve/index.html
@@ -9,6 +9,12 @@ <h2>Entry resolving with exports field</h2>
 <h2>Deep import with exports field</h2>
 <p class="exports-deep">fail</p>
 
+<h2>Deep import with exports field + exposed directory</h2>
+<p class="exports-deep-exposed-dir">fail</p>
+
+<h2>Deep import with exports field + mapped directory</h2>
+<p class="exports-deep-mapped-dir">fail</p>
+
 <h2>Resolve /index.*</h2>
 <p class="index">fail</p>
 
@@ -57,6 +63,14 @@ <h2>Inline package</h2>
   import { msg as deepMsg } from 'resolve-conditional-exports/deep.js'
   text('.exports-deep', deepMsg)
 
+  // deep import w/ exposed dir
+  import { msg as exposedDirMsg } from 'resolve-conditional-exports/dir/dir'
+  text('.exports-deep-exposed-dir', exposedDirMsg)
+
+  // deep import w/ mapped dir
+  import { msg as mappedDirMsg } from 'resolve-conditional-exports/dir-mapped/dir'
+  text('.exports-deep-mapped-dir', mappedDirMsg)
+
   // implicit index resolving
   import { foo } from './util'
   text('.index', foo())
diff --git a/packages/vite/src/node/plugins/resolve.ts b/packages/vite/src/node/plugins/resolve.ts
index 7ce0bb47cceb35..1506935257910e 100644
--- a/packages/vite/src/node/plugins/resolve.ts
+++ b/packages/vite/src/node/plugins/resolve.ts
@@ -417,13 +417,24 @@ function resolveDeepImport(
 
   // map relative based on exports data
   if (exportsField) {
-    if (
-      isObject(exportsField) &&
-      !Array.isArray(exportsField) &&
-      relativeId in exportsField
-    ) {
-      relativeId = resolveConditionalExports(exportsField[relativeId])
-    } else {
+    let isExported = false
+    if (isObject(exportsField) && !Array.isArray(exportsField)) {
+      if (relativeId in exportsField) {
+        relativeId = resolveConditionalExports(exportsField[relativeId])
+        isExported = true
+      } else {
+        for (const key in exportsField) {
+          if (key.endsWith('/') && relativeId.startsWith(key)) {
+            // directory mapping
+            const replacement = resolveConditionalExports(exportsField[key])
+            relativeId = replacement && relativeId.replace(key, replacement)
+            isExported = true
+            break
+          }
+        }
+      }
+    }
+    if (!isExported || !relativeId) {
       throw new Error(
         `Package subpath '${relativeId}' is not defined by "exports" in ` +
           `${path.join(dir, 'package.json')}.`