From 5f74775e5bcb5904edfb106d9c94577f500a8c7b Mon Sep 17 00:00:00 2001
From: tao <2471314@gmail.com>
Date: Sat, 18 Oct 2025 20:29:08 +0800
Subject: [PATCH] fix union type case

---
 .../src/rules/no-misused-promises.ts            |  8 ++++----
 .../tests/rules/no-misused-promises.test.ts     | 17 +++++++++++++++++
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/packages/eslint-plugin/src/rules/no-misused-promises.ts b/packages/eslint-plugin/src/rules/no-misused-promises.ts
index b791fe150584..74f0690a5174 100644
--- a/packages/eslint-plugin/src/rules/no-misused-promises.ts
+++ b/packages/eslint-plugin/src/rules/no-misused-promises.ts
@@ -502,10 +502,10 @@ export default createRule<Options, MessageId>({
         if (objType == null) {
           return;
         }
-        const propertySymbol = checker.getPropertyOfType(
-          objType,
-          tsNode.name.text,
-        );
+        const propertySymbol = tsutils
+          .unionConstituents(objType)
+          .map(t => checker.getPropertyOfType(t, tsNode.name.getText()))
+          .find(p => p);
         if (propertySymbol == null) {
           return;
         }
diff --git a/packages/eslint-plugin/tests/rules/no-misused-promises.test.ts b/packages/eslint-plugin/tests/rules/no-misused-promises.test.ts
index dc671e8869d6..fd908d416c08 100644
--- a/packages/eslint-plugin/tests/rules/no-misused-promises.test.ts
+++ b/packages/eslint-plugin/tests/rules/no-misused-promises.test.ts
@@ -2653,5 +2653,22 @@ const obj: O = {
         },
       ],
     },
+    {
+      code: `
+type A = { f: () => void } | undefined;
+const a: A = {
+  async f() {},
+};
+      `,
+      errors: [
+        {
+          column: 3,
+          endColumn: 10,
+          endLine: 4,
+          line: 4,
+          messageId: 'voidReturnProperty',
+        },
+      ],
+    },
   ],
 });