From d6eb4f24a463777200506c03fd55d8fa4e1ea394 Mon Sep 17 00:00:00 2001
From: Bjorn Lu <bjornlu.dev@gmail.com>
Date: Wed, 7 Dec 2022 21:34:51 +0800
Subject: [PATCH] fix(resolve): ensure exports has precedence over mainFields
 (#11234)

---
 packages/vite/src/node/plugins/resolve.ts           |  6 +++++-
 playground/resolve/__tests__/resolve.spec.ts        |  4 ++++
 playground/resolve/exports-with-module/import.mjs   |  2 ++
 playground/resolve/exports-with-module/module.mjs   |  2 ++
 playground/resolve/exports-with-module/package.json | 10 ++++++++++
 playground/resolve/index.html                       |  6 ++++++
 playground/resolve/package.json                     |  1 +
 pnpm-lock.yaml                                      |  5 +++++
 8 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 playground/resolve/exports-with-module/import.mjs
 create mode 100644 playground/resolve/exports-with-module/module.mjs
 create mode 100644 playground/resolve/exports-with-module/package.json

diff --git a/packages/vite/src/node/plugins/resolve.ts b/packages/vite/src/node/plugins/resolve.ts
index 2c45771c46e101..58ced293e89103 100644
--- a/packages/vite/src/node/plugins/resolve.ts
+++ b/packages/vite/src/node/plugins/resolve.ts
@@ -931,6 +931,8 @@ export function resolvePackageEntry(
       entryPoint = resolveExports(data, '.', options, targetWeb)
     }
 
+    const resolvedFromExports = !!entryPoint
+
     // if exports resolved to .mjs, still resolve other fields.
     // This is because .mjs files can technically import .cjs files which would
     // make them invalid for pure ESM environments - so if other module/browser
@@ -980,7 +982,9 @@ export function resolvePackageEntry(
       }
     }
 
-    if (!entryPoint || entryPoint.endsWith('.mjs')) {
+    // fallback to mainFields if still not resolved
+    // TODO: review if `.mjs` check is still needed
+    if (!resolvedFromExports && (!entryPoint || entryPoint.endsWith('.mjs'))) {
       for (const field of options.mainFields) {
         if (field === 'browser') continue // already checked above
         if (typeof data[field] === 'string') {
diff --git a/playground/resolve/__tests__/resolve.spec.ts b/playground/resolve/__tests__/resolve.spec.ts
index 2181f6d3c8433e..2371c55759728e 100644
--- a/playground/resolve/__tests__/resolve.spec.ts
+++ b/playground/resolve/__tests__/resolve.spec.ts
@@ -53,6 +53,10 @@ test('Respect production/development conditionals', async () => {
   )
 })
 
+test('Respect exports to take precedence over mainFields', async () => {
+  expect(await page.textContent('.exports-with-module')).toMatch('[success]')
+})
+
 test('implicit dir/index.js', async () => {
   expect(await page.textContent('.index')).toMatch('[success]')
 })
diff --git a/playground/resolve/exports-with-module/import.mjs b/playground/resolve/exports-with-module/import.mjs
new file mode 100644
index 00000000000000..d97c695169a575
--- /dev/null
+++ b/playground/resolve/exports-with-module/import.mjs
@@ -0,0 +1,2 @@
+// import.mjs should take precedence
+export const msg = '[success] exports with module (import.mjs)'
diff --git a/playground/resolve/exports-with-module/module.mjs b/playground/resolve/exports-with-module/module.mjs
new file mode 100644
index 00000000000000..f9392192058822
--- /dev/null
+++ b/playground/resolve/exports-with-module/module.mjs
@@ -0,0 +1,2 @@
+// import.mjs should take precedence
+export const msg = '[fail] exports with module (module.mjs)'
diff --git a/playground/resolve/exports-with-module/package.json b/playground/resolve/exports-with-module/package.json
new file mode 100644
index 00000000000000..b3d9f7e999ca75
--- /dev/null
+++ b/playground/resolve/exports-with-module/package.json
@@ -0,0 +1,10 @@
+{
+  "name": "@vitejs/test-resolve-exports-with-module",
+  "private": true,
+  "version": "1.0.0",
+  "type": "commonjs",
+  "module": "./module.mjs",
+  "exports": {
+    "import": "./import.mjs"
+  }
+}
diff --git a/playground/resolve/index.html b/playground/resolve/index.html
index 9aa1261f98c980..3a6ba0cc930024 100644
--- a/playground/resolve/index.html
+++ b/playground/resolve/index.html
@@ -27,6 +27,9 @@ <h2>Exports field env priority</h2>
 <h2>Exports with legacy fallback</h2>
 <p class="exports-legacy-fallback">fail</p>
 
+<h2>Exports with module</h2>
+<p class="exports-with-module">fail</p>
+
 <h2>Resolve /index.*</h2>
 <p class="index">fail</p>
 
@@ -169,6 +172,9 @@ <h2>resolve package that contains # in path</h2>
   import { msg as exportsLegacyFallbackMsg } from '@vitejs/test-resolve-exports-legacy-fallback/dir'
   text('.exports-legacy-fallback', exportsLegacyFallbackMsg)
 
+  import { msg as exportsWithModule } from '@vitejs/test-resolve-exports-with-module'
+  text('.exports-with-module', exportsWithModule)
+
   // implicit index resolving
   import { foo } from './util'
   text('.index', foo())
diff --git a/playground/resolve/package.json b/playground/resolve/package.json
index d7e5f07b17f845..bccde4be65bb1f 100644
--- a/playground/resolve/package.json
+++ b/playground/resolve/package.json
@@ -22,6 +22,7 @@
     "@vitejs/test-resolve-exports-env": "link:./exports-env",
     "@vitejs/test-resolve-exports-legacy-fallback": "link:./exports-legacy-fallback",
     "@vitejs/test-resolve-exports-path": "link:./exports-path",
+    "@vitejs/test-resolve-exports-with-module": "link:./exports-with-module",
     "@vitejs/test-resolve-linked": "workspace:*"
   }
 }
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index a59098cb33ccdb..23cf6f4d637c8d 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -801,6 +801,7 @@ importers:
       '@vitejs/test-resolve-exports-env': link:./exports-env
       '@vitejs/test-resolve-exports-legacy-fallback': link:./exports-legacy-fallback
       '@vitejs/test-resolve-exports-path': link:./exports-path
+      '@vitejs/test-resolve-exports-with-module': link:./exports-with-module
       '@vitejs/test-resolve-linked': workspace:*
       es5-ext: 0.10.62
       normalize.css: ^8.0.1
@@ -816,6 +817,7 @@ importers:
       '@vitejs/test-resolve-exports-env': link:exports-env
       '@vitejs/test-resolve-exports-legacy-fallback': link:exports-legacy-fallback
       '@vitejs/test-resolve-exports-path': link:exports-path
+      '@vitejs/test-resolve-exports-with-module': link:exports-with-module
       '@vitejs/test-resolve-linked': link:../resolve-linked
       es5-ext: 0.10.62
       normalize.css: 8.0.1
@@ -856,6 +858,9 @@ importers:
   playground/resolve/exports-path:
     specifiers: {}
 
+  playground/resolve/exports-with-module:
+    specifiers: {}
+
   playground/resolve/inline-package:
     specifiers: {}