From 5dbd6b36a0666fc6c993115ee5281ef253ba8a68 Mon Sep 17 00:00:00 2001
From: wonderful-panda <iwata0303@gmail.com>
Date: Tue, 22 Sep 2020 23:05:37 +0900
Subject: [PATCH] fix(types): fix using tuple type as EmitsOptions (#2160)

fix #2159
---
 packages/runtime-core/src/componentEmits.ts | 4 ++--
 test-dts/functionalComponent.test-d.tsx     | 9 +++++++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/packages/runtime-core/src/componentEmits.ts b/packages/runtime-core/src/componentEmits.ts
index 6418f8c7d..daf82b71e 100644
--- a/packages/runtime-core/src/componentEmits.ts
+++ b/packages/runtime-core/src/componentEmits.ts
@@ -28,8 +28,8 @@ export type EmitsOptions = ObjectEmitsOptions | string[]
 export type EmitFn<
   Options = ObjectEmitsOptions,
   Event extends keyof Options = keyof Options
-> = Options extends any[]
-  ? (event: Options[0], ...args: any[]) => void
+> = Options extends Array<infer V>
+  ? (event: V, ...args: any[]) => void
   : {} extends Options // if the emit is empty object (usually the default value for emit) should be converted to function
     ? (event: string, ...args: any[]) => void
     : UnionToIntersection<
diff --git a/test-dts/functionalComponent.test-d.tsx b/test-dts/functionalComponent.test-d.tsx
index c53c4287a..4fe4db645 100644
--- a/test-dts/functionalComponent.test-d.tsx
+++ b/test-dts/functionalComponent.test-d.tsx
@@ -63,3 +63,12 @@ const Baz: FunctionalComponent<{}, string[]> = (props, { emit }) => {
 }
 
 expectType<Component>(Baz)
+
+const Qux: FunctionalComponent<{}, ['foo', 'bar']> = (props, { emit }) => {
+  emit('foo')
+  emit('foo', 1, 2)
+  emit('bar')
+  emit('bar', 1, 2)
+}
+
+expectType<Component>(Qux)