From 1383f6e24e384db0a9179f7ea6e40762f474233a Mon Sep 17 00:00:00 2001
From: sapphi-red <green@sapphi.red>
Date: Mon, 14 Dec 2020 23:49:33 +0900
Subject: [PATCH] fix(runtime-core): force evalutating SetupContext type (fix
 #2362)

---
 packages/runtime-core/src/component.ts | 15 +++++++++------
 test-dts/component.test-d.ts           | 12 +++++++++++-
 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/packages/runtime-core/src/component.ts b/packages/runtime-core/src/component.ts
index 788a20b4343..9f52dbaed01 100644
--- a/packages/runtime-core/src/component.ts
+++ b/packages/runtime-core/src/component.ts
@@ -167,12 +167,15 @@ export const enum LifecycleHooks {
   ERROR_CAPTURED = 'ec'
 }
 
-export interface SetupContext<E = EmitsOptions> {
-  attrs: Data
-  slots: Slots
-  emit: EmitFn<E>
-  expose: (exposed: Record<string, any>) => void
-}
+// use `E extends any` to force evaluating type to fix #2362
+export type SetupContext<E = EmitsOptions> = E extends any
+  ? {
+      attrs: Data
+      slots: Slots
+      emit: EmitFn<E>
+      expose: (exposed: Record<string, any>) => void
+    }
+  : never
 
 /**
  * @internal
diff --git a/test-dts/component.test-d.ts b/test-dts/component.test-d.ts
index 30b3b8e5f53..b314ba7880d 100644
--- a/test-dts/component.test-d.ts
+++ b/test-dts/component.test-d.ts
@@ -9,7 +9,9 @@ import {
   expectType,
   ShallowUnwrapRef,
   FunctionalComponent,
-  ComponentPublicInstance
+  ComponentPublicInstance,
+  SetupContext,
+  expectAssignable
 } from './index'
 
 declare function extractComponentOptions<Props, RawBindings>(
@@ -423,3 +425,11 @@ describe('class', () => {
 
   expectType<number>(props.foo)
 })
+
+describe('SetupContext', () => {
+  describe('can assign', () => {
+    const wider: SetupContext<{ a: () => true; b: () => true }> = {} as any
+
+    expectAssignable<SetupContext<{ b: () => true }>>(wider)
+  })
+})