fix(resolve): respect exports env key order

fix #1418

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

@@ -22,6 +22,10 @@ test('deep import with exports field + mapped dir', async () => {
   )
 })
 
+test('Respect exports field env key priority', async () => {
+  expect(await page.textContent('.exports-env')).toMatch('[success]')
+})
+
 test('omitted index/*', async () => {
   expect(await page.textContent('.index')).toMatch('[success]')
 })

packages/playground/resolve/exports-env/browser.js

@@ -0,0 +1 @@
+export const msg = 'fail (browser.js)'

packages/playground/resolve/exports-env/browser.mjs

@@ -0,0 +1 @@
+export const msg = '[success] exports env (browser.mjs)'

packages/playground/resolve/exports-env/fallback.umd.js

@@ -0,0 +1 @@
+export const msg = 'fail (fallback.umd.js)'

packages/playground/resolve/exports-env/package.json

@@ -0,0 +1,11 @@
+{
+  "name": "resolve-exports-env",
+  "version": "1.0.0",
+  "exports": {
+    "import": {
+      "browser": "./browser.mjs"
+    },
+    "browser": "./browser.js",
+    "default": "./fallback.umd.js"
+  }
+}

packages/playground/resolve/conditional-exports/package.json → packages/playground/resolve/exports-path/package.json

@@ -1,5 +1,5 @@
 {
-  "name": "resolve-conditional-exports",
+  "name": "resolve-exports-path",
   "version": "1.0.0",
   "exports": {
     ".": {

packages/playground/resolve/index.html

@@ -15,6 +15,9 @@ <h2>Deep import with exports field + exposed directory</h2>
 <h2>Deep import with exports field + mapped directory</h2>
 <p class="exports-deep-mapped-dir">fail</p>
 
+<h2>Exports field env priority</h2>
+<p class="exports-env">fail</p>
+
 <h2>Resolve /index.*</h2>
 <p class="index">fail</p>
 
@@ -56,21 +59,24 @@ <h2>Inline package</h2>
   ))
 
   // exports field
-  import { msg } from 'resolve-conditional-exports'
+  import { msg } from 'resolve-exports-path'
   text('.exports-entry', msg)
 
   // deep import w/ exports
-  import { msg as deepMsg } from 'resolve-conditional-exports/deep.js'
+  import { msg as deepMsg } from 'resolve-exports-path/deep.js'
   text('.exports-deep', deepMsg)
 
   // deep import w/ exposed dir
-  import { msg as exposedDirMsg } from 'resolve-conditional-exports/dir/dir'
+  import { msg as exposedDirMsg } from 'resolve-exports-path/dir/dir'
   text('.exports-deep-exposed-dir', exposedDirMsg)
 
   // deep import w/ mapped dir
-  import { msg as mappedDirMsg } from 'resolve-conditional-exports/dir-mapped/dir'
+  import { msg as mappedDirMsg } from 'resolve-exports-path/dir-mapped/dir'
   text('.exports-deep-mapped-dir', mappedDirMsg)
 
+  import { msg as exportsEnvMsg } from 'resolve-exports-env'
+  text('.exports-env', exportsEnvMsg)
+
   // implicit index resolving
   import { foo } from './util'
   text('.index', foo())

packages/playground/resolve/package.json

@@ -8,7 +8,8 @@
     "debug": "node --inspect-brk ../../vite/bin/vite"
   },
   "dependencies": {
-    "resolve-conditional-exports": "link:./conditional-exports",
+    "resolve-exports-path": "link:./exports-path",
+    "resolve-exports-env": "link:./exports-env",
     "resolve-browser-field": "link:./browser-field",
     "@babel/runtime": "^7.12.5",
     "normalize.css": "^8.0.1"

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

@@ -381,17 +381,7 @@ export function resolvePackageEntry(
     // https://nodejs.org/api/packages.html#packages_package_entry_points
     const { exports: exportsField } = data
     if (exportsField) {
-      if (typeof exportsField === 'string') {
-        entryPoint = exportsField
-      } else if (Array.isArray(exportsField)) {
-        entryPoint = exportsField[0]
-      } else if (isObject(exportsField)) {
-        if ('.' in exportsField) {
-          entryPoint = resolveConditionalExports(exportsField['.'])
-        } else {
-          entryPoint = resolveConditionalExports(exportsField)
-        }
-      }
+      entryPoint = resolveConditionalExports(exportsField, '.')
     }
   }
 
@@ -439,24 +429,13 @@ function resolveDeepImport(
 
   // map relative based on exports data
   if (exportsField) {
-    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
-          }
-        }
-      }
+      relativeId = resolveConditionalExports(exportsField, relativeId)
+    } else {
+      // not exposed
+      relativeId = undefined
     }
-    if (!isExported || !relativeId) {
+    if (!relativeId) {
       throw new Error(
         `Package subpath '${relativeId}' is not defined by "exports" in ` +
           `${path.join(dir, 'package.json')}.`
@@ -481,20 +460,51 @@ function resolveDeepImport(
   }
 }
 
-function resolveConditionalExports(exp: any): string | undefined {
+const ENV_KEYS = [
+  'esmodules',
+  'import',
+  'module',
+  'require',
+  'browser',
+  'node',
+  'default'
+]
+
+function resolveConditionalExports(exp: any, id: string): string | undefined {
   if (typeof exp === 'string') {
     return exp
   } else if (isObject(exp)) {
-    if (typeof exp.browser === 'string') {
-      return exp.browser
-    } else if (typeof exp.import === 'string') {
-      return exp.import
-    } else if (typeof exp.default === 'string') {
-      return exp.default
+    let isFileListing: boolean | undefined
+    let fallback: string | undefined
+    for (const key in exp) {
+      if (isFileListing === undefined) {
+        isFileListing = key[0] === '.'
+      }
+      if (isFileListing) {
+        if (key === id) {
+          return resolveConditionalExports(exp[key], id)
+        } else if (key.endsWith('/') && id.startsWith(key)) {
+          // mapped directory
+          const replacement = resolveConditionalExports(exp[key], id)
+          return replacement && id.replace(key, replacement)
+        }
+      } else if (ENV_KEYS.includes(key)) {
+        // https://github.com/vitejs/vite/issues/1418
+        // respect env key order
+        // but intentionally de-prioritize "require" and "default" keys
+        if (key === 'require' || key === 'default') {
+          if (!fallback) fallback = key
+        } else {
+          return resolveConditionalExports(exp[key], id)
+        }
+      }
+      if (fallback) {
+        return resolveConditionalExports(exp[key], id)
+      }
     }
   } else if (Array.isArray(exp)) {
     for (let i = 0; i < exp.length; i++) {
-      const res = resolveConditionalExports(exp[i])
+      const res = resolveConditionalExports(exp[i], id)
       if (res) return res
     }
   }

yarn.lock

@@ -7067,17 +7067,21 @@ requires-port@^1.0.0:
   version "0.0.0"
   uid ""
 
-"resolve-conditional-exports@link:./packages/playground/resolve/conditional-exports":
-  version "0.0.0"
-  uid ""
-
 resolve-cwd@^3.0.0:
   version "3.0.0"
   resolved "https://registry.yarnpkg.com/resolve-cwd/-/resolve-cwd-3.0.0.tgz#0f0075f1bb2544766cf73ba6a6e2adfebcb13f2d"
   integrity sha512-OrZaX2Mb+rJCpH/6CpSqt9xFVpN++x01XnN2ie9g6P5/3xelLAkXWVADpdz1IHD/KFfEXyE6V0U01OQ3UO2rEg==
   dependencies:
     resolve-from "^5.0.0"
 
+"resolve-exports-env@link:./packages/playground/resolve/exports-env":
+  version "0.0.0"
+  uid ""
+
+"resolve-exports-path@link:./packages/playground/resolve/exports-path":
+  version "0.0.0"
+  uid ""
+
 resolve-from@^4.0.0:
   version "4.0.0"
   resolved "https://registry.yarnpkg.com/resolve-from/-/resolve-from-4.0.0.tgz#4abcd852ad32dd7baabfe9b40e00a36db5f392e6"