fix(language-core): drop undefined from type of optional prop with default in template

packages/language-core/lib/codegen/localTypes.ts

@@ -1,9 +1,8 @@
-import type * as ts from 'typescript';
 import type { VueCompilerOptions } from '../types';
 import { getSlotsPropertyName } from '../utils/shared';
 import { endOfLine } from './utils';
 
-export function getLocalTypesGenerator(compilerOptions: ts.CompilerOptions, vueCompilerOptions: VueCompilerOptions) {
+export function getLocalTypesGenerator(vueCompilerOptions: VueCompilerOptions) {
 	const used = new Set<string>();
 
 	const OmitKeepDiscriminatedUnion = defineHelper(
@@ -19,7 +18,7 @@ type __VLS_OmitKeepDiscriminatedUnion<T, K extends keyof any> = T extends any
 		() => `
 type __VLS_WithDefaults<P, D> = {
 	[K in keyof Pick<P, keyof P>]: K extends keyof D
-		? ${PrettifyLocal.name}<P[K] & { default: D[K]}>
+		? ${PrettifyLocal.name}<P[K] & { default: D[K] }>
 		: P[K]
 };
 `.trimStart()
@@ -59,19 +58,10 @@ type __VLS_PropsChildren<S> = {
 	);
 	const TypePropsToOption = defineHelper(
 		`__VLS_TypePropsToOption`,
-		() => compilerOptions.exactOptionalPropertyTypes ?
-			`
-type __VLS_TypePropsToOption<T> = {
-	[K in keyof T]-?: {} extends Pick<T, K>
-		? { type: import('${vueCompilerOptions.lib}').PropType<T[K]> }
-		: { type: import('${vueCompilerOptions.lib}').PropType<T[K]>, required: true }
-};
-`.trimStart() :
-			`
-type __VLS_NonUndefinedable<T> = T extends undefined ? never : T;
+		() => `
 type __VLS_TypePropsToOption<T> = {
 	[K in keyof T]-?: {} extends Pick<T, K>
-		? { type: import('${vueCompilerOptions.lib}').PropType<__VLS_NonUndefinedable<T[K]>> }
+		? { type: import('${vueCompilerOptions.lib}').PropType<Required<T>[K]> }
 		: { type: import('${vueCompilerOptions.lib}').PropType<T[K]>, required: true }
 };
 `.trimStart()

packages/language-core/lib/codegen/script/context.ts

@@ -12,7 +12,7 @@ export interface HelperType {
 export type ScriptCodegenContext = ReturnType<typeof createScriptCodegenContext>;
 
 export function createScriptCodegenContext(options: ScriptCodegenOptions) {
-	const localTypes = getLocalTypesGenerator(options.compilerOptions, options.vueCompilerOptions);
+	const localTypes = getLocalTypesGenerator(options.vueCompilerOptions);
 	const inlayHints: InlayHintInfo[] = [];
 
 	return {

test-workspace/tsc/passedFixtures/#5338/main.vue

@@ -0,0 +1,15 @@
+<script setup lang="ts">
+import { exactType } from '../shared';
+
+withDefaults(defineProps<{
+    foo?: string;
+    bar?: string;
+}>(), {
+    foo: 'foo',
+});
+</script>
+
+<template>
+    {{ exactType(foo, {} as string) }}
+    {{ exactType(bar, {} as string | undefined) }}
+</template>

test-workspace/tsc/passedFixtures/#5338/tsconfig.json

@@ -0,0 +1,10 @@
+{
+	"extends": "../../../tsconfig.base.json",
+	"compilerOptions": {
+		"exactOptionalPropertyTypes": true
+	},
+	"vueCompilerOptions": {
+		"target": 3.5
+	},
+	"include": [ "**/*" ]
+}