From ebc4f0f1987298ef20ed4a97f62277637717f501 Mon Sep 17 00:00:00 2001
From: xienan <1633875789@qq.com>
Date: Sun, 30 Nov 2025 19:23:58 +0800
Subject: [PATCH 1/2] fix(types): enable proper type narrowing for defineEmits
 (#13935)

---
 .../dts-test/issue-13935.test-d.ts            | 21 +++++++++++++++++++
 packages/runtime-core/src/apiSetupHelpers.ts  | 12 ++++-------
 2 files changed, 25 insertions(+), 8 deletions(-)
 create mode 100644 packages-private/dts-test/issue-13935.test-d.ts

diff --git a/packages-private/dts-test/issue-13935.test-d.ts b/packages-private/dts-test/issue-13935.test-d.ts
new file mode 100644
index 00000000000..24a3a778568
--- /dev/null
+++ b/packages-private/dts-test/issue-13935.test-d.ts
@@ -0,0 +1,21 @@
+import { defineEmits } from 'vue'
+import { describe } from './utils'
+
+describe('defineEmits w/ type declaration (Issue #13935)', () => {
+  const emit = defineEmits<{
+    open: [payload: number]
+    close: [payload: string]
+  }>()
+
+  // Correct usages
+  emit('open', 123)
+  emit('close', 'abc')
+
+  // Incorrect usages (should fail type check)
+  // @ts-expect-error
+  emit('open', 'string')
+  // @ts-expect-error
+  emit('close', 123)
+  // @ts-expect-error
+  emit('unknown', 123)
+})
diff --git a/packages/runtime-core/src/apiSetupHelpers.ts b/packages/runtime-core/src/apiSetupHelpers.ts
index 67e1d550387..d784098df50 100644
--- a/packages/runtime-core/src/apiSetupHelpers.ts
+++ b/packages/runtime-core/src/apiSetupHelpers.ts
@@ -2,7 +2,6 @@ import {
   type IfAny,
   type LooseRequired,
   type Prettify,
-  type UnionToIntersection,
   extend,
   isArray,
   isFunction,
@@ -151,13 +150,10 @@ export function defineEmits() {
 
 export type ComponentTypeEmits = ((...args: any[]) => any) | Record<string, any>
 
-type RecordToUnion<T extends Record<string, any>> = T[keyof T]
-
-type ShortEmits<T extends Record<string, any>> = UnionToIntersection<
-  RecordToUnion<{
-    [K in keyof T]: (evt: K, ...args: T[K]) => void
-  }>
->
+type ShortEmits<T extends Record<string, any>> = <K extends keyof T>(
+  evt: K,
+  ...args: T[K]
+) => void
 
 /**
  * Vue `<script setup>` compiler macro for declaring a component's exposed

From ba68414e80bc25228727411580acd3de18b523bc Mon Sep 17 00:00:00 2001
From: xienan <1633875789@qq.com>
Date: Mon, 1 Dec 2025 10:46:58 +0800
Subject: [PATCH 2/2] test: move issue 13935 test to setupHelpers.test-d.ts

---
 .../dts-test/issue-13935.test-d.ts            | 21 -------------------
 .../dts-test/setupHelpers.test-d.ts           | 19 +++++++++++++++++
 2 files changed, 19 insertions(+), 21 deletions(-)
 delete mode 100644 packages-private/dts-test/issue-13935.test-d.ts

diff --git a/packages-private/dts-test/issue-13935.test-d.ts b/packages-private/dts-test/issue-13935.test-d.ts
deleted file mode 100644
index 24a3a778568..00000000000
--- a/packages-private/dts-test/issue-13935.test-d.ts
+++ /dev/null
@@ -1,21 +0,0 @@
-import { defineEmits } from 'vue'
-import { describe } from './utils'
-
-describe('defineEmits w/ type declaration (Issue #13935)', () => {
-  const emit = defineEmits<{
-    open: [payload: number]
-    close: [payload: string]
-  }>()
-
-  // Correct usages
-  emit('open', 123)
-  emit('close', 'abc')
-
-  // Incorrect usages (should fail type check)
-  // @ts-expect-error
-  emit('open', 'string')
-  // @ts-expect-error
-  emit('close', 123)
-  // @ts-expect-error
-  emit('unknown', 123)
-})
diff --git a/packages-private/dts-test/setupHelpers.test-d.ts b/packages-private/dts-test/setupHelpers.test-d.ts
index 656f1da79f2..a9fb72a6e97 100644
--- a/packages-private/dts-test/setupHelpers.test-d.ts
+++ b/packages-private/dts-test/setupHelpers.test-d.ts
@@ -632,3 +632,22 @@ describe('defineOptions', () => {
     expose: ['expose'],
   })
 })
+
+describe('defineEmits w/ type declaration (Issue #13935)', () => {
+  const emit = defineEmits<{
+    open: [payload: number]
+    close: [payload: string]
+  }>()
+
+  // Correct usages
+  emit('open', 123)
+  emit('close', 'abc')
+
+  // Incorrect usages (should fail type check)
+  // @ts-expect-error
+  emit('open', 'string')
+  // @ts-expect-error
+  emit('close', 123)
+  // @ts-expect-error
+  emit('unknown', 123)
+})