From 801b823a86299229f0c916243b20a8f388a1d41d Mon Sep 17 00:00:00 2001
From: sapphi-red <49056869+sapphi-red@users.noreply.github.com>
Date: Wed, 2 Jul 2025 17:40:52 +0900
Subject: [PATCH] fix(define): replace optional values

---
 packages/vite/src/node/plugins/define.ts   | 8 +++++++-
 playground/define/__tests__/define.spec.ts | 6 ++++++
 playground/define/index.html               | 9 +++++++++
 playground/define/optional-env.js          | 2 ++
 4 files changed, 24 insertions(+), 1 deletion(-)
 create mode 100644 playground/define/optional-env.js

diff --git a/packages/vite/src/node/plugins/define.ts b/packages/vite/src/node/plugins/define.ts
index 5be259c26ff27b..ef4c8af77a6084 100644
--- a/packages/vite/src/node/plugins/define.ts
+++ b/packages/vite/src/node/plugins/define.ts
@@ -10,6 +10,7 @@ const nonJsRe = /\.json(?:$|\?)/
 const isNonJsRequest = (request: string): boolean => nonJsRe.test(request)
 const importMetaEnvMarker = '__vite_import_meta_env__'
 const importMetaEnvKeyReCache = new Map<string, RegExp>()
+const escapedDotRE = /(?<!\\)\\./g
 
 export function definePlugin(config: ResolvedConfig): Plugin {
   const isBuild = config.command === 'build'
@@ -91,7 +92,12 @@ export function definePlugin(config: ResolvedConfig): Plugin {
       patternKeys.push('import.meta.env', 'import.meta.hot')
     }
     const pattern = patternKeys.length
-      ? new RegExp(patternKeys.map(escapeRegex).join('|'))
+      ? new RegExp(
+          patternKeys
+            // replace `\.` (ignore `\\.`) with `\??\.` to match with `?.` as well
+            .map((key) => escapeRegex(key).replaceAll(escapedDotRE, '\\??\\.'))
+            .join('|'),
+        )
       : null
 
     return [define, pattern, importMetaEnvVal] as const
diff --git a/playground/define/__tests__/define.spec.ts b/playground/define/__tests__/define.spec.ts
index 71fa61035a8f31..4457a88c4ad073 100644
--- a/playground/define/__tests__/define.spec.ts
+++ b/playground/define/__tests__/define.spec.ts
@@ -109,3 +109,9 @@ test('replace constants on import.meta.env when it is a invalid json', async ()
     ),
   ).toBe('true')
 })
+
+test('optional values are detected by pattern properly', async () => {
+  expect(await page.textContent('.optional-env')).toBe(
+    JSON.parse(defines['process.env.SOMEVAR']),
+  )
+})
diff --git a/playground/define/index.html b/playground/define/index.html
index 7c8fc55ba302cf..9d48f81f303d80 100644
--- a/playground/define/index.html
+++ b/playground/define/index.html
@@ -72,6 +72,12 @@ <h2>Define undefined constants on import.meta.env when it's a invalid json</h2>
   </p>
 </section>
 
+<h2>Optional values are detected by pattern properly</h2>
+<p>
+  process?.env?.SOMEVAR
+  <code class="optional-env"></code>
+</p>
+
 <script>
   // inject __VITE_SOME_IDENTIFIER__ to test if it's replaced
   window.__VITE_SOME_IDENTIFIER__ = true
@@ -154,6 +160,9 @@ <h2>Define undefined constants on import.meta.env when it's a invalid json</h2>
     '.replace-undefined-constants-on-import-meta-env .import-meta-env-SOME_IDENTIFIER',
     `${import.meta.env.SOME_IDENTIFIER}`,
   )
+
+  import optionalEnv from './optional-env.js'
+  text('.optional-env', optionalEnv)
 </script>
 
 <style>
diff --git a/playground/define/optional-env.js b/playground/define/optional-env.js
new file mode 100644
index 00000000000000..eb86cbfe22419c
--- /dev/null
+++ b/playground/define/optional-env.js
@@ -0,0 +1,2 @@
+// separate file to test pattern filter
+export default process?.env?.SOMEVAR