fix(language-core): infer parameter type of union slots to be union instead of intersection (#5475)

KazariEX · web-flow · commit abb5f2b6c4be · 2025-07-02T22:45:38.000-07:00
diff --git a/packages/language-core/lib/codegen/globalTypes.ts b/packages/language-core/lib/codegen/globalTypes.ts
@@ -164,7 +164,7 @@ export function generateGlobalTypes({
 		index: number,
 	][];
 	function __VLS_getSlotParameters<S, D extends S>(slot: S, decl?: D):
-		__VLS_PickNotAny<NonNullable<D>, (...args: any) => any> extends (...args: infer P) => any ? P : any[];
+		D extends (...args: infer P) => any ? P : any[];
 	function __VLS_asFunctionalDirective<T>(dir: T): T extends import('${lib}').ObjectDirective
 		? NonNullable<T['created' | 'beforeMount' | 'mounted' | 'beforeUpdate' | 'updated' | 'beforeUnmount' | 'unmounted']>
 		: T extends (...args: any) => any
diff --git a/packages/language-core/lib/codegen/template/vSlot.ts b/packages/language-core/lib/codegen/template/vSlot.ts
@@ -154,7 +154,7 @@ function* generateSlotParameters(
 		nextStart = end;
 	}
 	yield chunk(nextStart, expression.equalsGreaterThanToken.pos - 1);
-	yield `] = __VLS_getSlotParameters(${slotVar}`;
+	yield `] = __VLS_getSlotParameters(${slotVar}!`;
 
 	if (types.some(t => t)) {
 		yield `, `;
diff --git a/test-workspace/tsc/passedFixtures/vue3/#5474/main.vue b/test-workspace/tsc/passedFixtures/vue3/#5474/main.vue
@@ -0,0 +1,19 @@
+<script setup lang="ts">
+import { exactType } from '../../shared';
+
+type Foo = { foo: string };
+type Bar = { bar: string };
+
+declare const Comp: (props: {}, ctx: { slots: {
+	foo: (props: Foo) => void;
+	bar: (props: Bar) => void;
+} }) => {};
+</script>
+
+<template>
+	<Comp>
+		<template v-for="name in (['foo', 'bar'] as const)" #[name]="props">
+			{{ exactType(props, {} as Foo | Bar) }}
+		</template>
+	</Comp>
+</template>

Original file line number	Diff line number	Diff line change
`@@ -154,7 +154,7 @@ function* generateSlotParameters(`
`154`	`154`	`nextStart = end;`
`155`	`155`	`}`
`156`	`156`	`yield chunk(nextStart, expression.equalsGreaterThanToken.pos - 1);`
`157`		- yield `] = __VLS_getSlotParameters(${slotVar}`;
	`157`	+ yield `] = __VLS_getSlotParameters(${slotVar}!`;
`158`	`158`
`159`	`159`	`if (types.some(t => t)) {`
`160`	`160`	yield `, `;