feat: undefined slot scope

Author: sxzz

packages/dts-test/defineComponent.test-d.tsx

@@ -1414,6 +1414,8 @@ describe('slots', () => {
     slots: Object as SlotsType<{
       default: { foo: string; bar: number }
       optional?: { data: string }
+      undefinedScope: undefined | { data: string }
+      optionalUndefinedScope?: undefined | { data: string }
     }>,
     setup(props, { slots }) {
       expectType<(scope: { foo: string; bar: number }) => VNode[]>(
@@ -1429,6 +1431,33 @@ describe('slots', () => {
       slots.optional({ data: 'foo' })
       slots.optional?.({ data: 'foo' })
 
+      expectType<{
+        (): VNode[]
+        (scope: undefined | { data: string }): VNode[]
+      }>(slots.undefinedScope)
+
+      expectType<
+        | { (): VNode[]; (scope: undefined | { data: string }): VNode[] }
+        | undefined
+      >(slots.optionalUndefinedScope)
+
+      slots.default({ foo: 'foo', bar: 1 })
+      // @ts-expect-error it's optional
+      slots.optional({ data: 'foo' })
+      slots.optional?.({ data: 'foo' })
+      slots.undefinedScope()
+      slots.undefinedScope(undefined)
+      // @ts-expect-error
+      slots.undefinedScope('foo')
+
+      slots.optionalUndefinedScope?.()
+      slots.optionalUndefinedScope?.(undefined)
+      slots.optionalUndefinedScope?.({ data: 'foo' })
+      // @ts-expect-error
+      slots.optionalUndefinedScope()
+      // @ts-expect-error
+      slots.optionalUndefinedScope?.('foo')
+
       expectType<typeof slots | undefined>(new comp1().$slots)
     }
   })

packages/runtime-core/src/componentSlots.ts

@@ -25,7 +25,7 @@ import { DeprecationTypes, isCompatEnabled } from './compat/compatConfig'
 import { toRaw } from '@vue/reactivity'
 
 export type Slot<T extends any = any> = (
-  ...args: IfAny<T, any[], [T]>
+  ...args: IfAny<T, any[], [T] | (T extends undefined ? [] : never)>
 ) => VNode[]
 
 export type InternalSlots = {
@@ -44,7 +44,7 @@ export type TypedSlots<S extends SlotsType> = [keyof S] extends [never]
   : Readonly<
       Prettify<{
         [K in keyof NonNullable<S[typeof SlotSymbol]>]: Slot<
-          NonNullable<NonNullable<S[typeof SlotSymbol]>[K]>
+          NonNullable<S[typeof SlotSymbol]>[K]
         >
       }>
     >