From 51bd9307a6770fdd84cc049f7cf315181a06c27d Mon Sep 17 00:00:00 2001
From: Johnson Chu <johnsoncodehk@gmail.com>
Date: Tue, 27 Aug 2024 18:02:51 +0800
Subject: [PATCH] fix(language-core): fallthrough attributes break component
 type when root tag type is unknown (#4729)

---
 .../lib/codegen/script/component.ts             | 17 ++++++++++++-----
 .../inheritAttrs_unknownTag/basic.vue           |  7 +++++++
 .../inheritAttrs_unknownTag/main.vue            |  7 +++++++
 3 files changed, 26 insertions(+), 5 deletions(-)
 create mode 100644 test-workspace/tsc/passedFixtures/vue3_strictTemplate/inheritAttrs_unknownTag/basic.vue
 create mode 100644 test-workspace/tsc/passedFixtures/vue3_strictTemplate/inheritAttrs_unknownTag/main.vue

diff --git a/packages/language-core/lib/codegen/script/component.ts b/packages/language-core/lib/codegen/script/component.ts
index ca7cf0b44d..6ed34d5a3c 100644
--- a/packages/language-core/lib/codegen/script/component.ts
+++ b/packages/language-core/lib/codegen/script/component.ts
@@ -128,10 +128,6 @@ export function* generatePropsOption(
 	const optionExpCodes: Code[] = [];
 	const typeOptionExpCodes: Code[] = [];
 
-	if (inheritAttrs && options.templateCodegen?.inheritedAttrVars.size && !hasEmitsOption) {
-		optionExpCodes.push(`{} as ${ctx.helperTypes.TypePropsToOption.name}<__VLS_PickNotAny<${ctx.helperTypes.OmitIndexSignature.name}<ReturnType<typeof __VLS_template>['attrs']>, {}>>`);
-		typeOptionExpCodes.push(`{} as ReturnType<typeof __VLS_template>['attrs']`);
-	}
 	if (ctx.generatedPropsType) {
 		optionExpCodes.push([
 			`{} as `,
@@ -141,11 +137,22 @@ export function* generatePropsOption(
 		].join(''));
 		typeOptionExpCodes.push(`{} as __VLS_PublicProps`);
 	}
-
 	if (scriptSetupRanges.props.define?.arg) {
 		const { arg } = scriptSetupRanges.props.define;
 		optionExpCodes.push(generateSfcBlockSection(scriptSetup, arg.start, arg.end, codeFeatures.navigation));
 	}
+	if (inheritAttrs && options.templateCodegen?.inheritedAttrVars.size && !hasEmitsOption) {
+		const attrsType = `ReturnType<typeof __VLS_template>['attrs']`;
+		const optionType = `${ctx.helperTypes.TypePropsToOption.name}<__VLS_PickNotAny<${ctx.helperTypes.OmitIndexSignature.name}<${attrsType}>, {}>>`;
+		if (optionExpCodes.length) {
+			optionExpCodes.unshift(`{} as ${optionType}`);
+		}
+		else {
+			// workaround for https://github.com/vuejs/core/pull/7419
+			optionExpCodes.unshift(`{} as keyof ${attrsType} extends never ? never: ${optionType}`);
+		}
+		typeOptionExpCodes.unshift(`{} as ${attrsType}`);
+	}
 
 	const useTypeOption = options.vueCompilerOptions.target >= 3.5 && typeOptionExpCodes.length;
 	const useOption = (!useTypeOption || scriptSetupRanges.props.withDefaults) && optionExpCodes.length;
diff --git a/test-workspace/tsc/passedFixtures/vue3_strictTemplate/inheritAttrs_unknownTag/basic.vue b/test-workspace/tsc/passedFixtures/vue3_strictTemplate/inheritAttrs_unknownTag/basic.vue
new file mode 100644
index 0000000000..88fa3d63aa
--- /dev/null
+++ b/test-workspace/tsc/passedFixtures/vue3_strictTemplate/inheritAttrs_unknownTag/basic.vue
@@ -0,0 +1,7 @@
+<script setup lang="ts">
+declare const child: unknown;
+</script>
+
+<template>
+	<child />
+</template>
diff --git a/test-workspace/tsc/passedFixtures/vue3_strictTemplate/inheritAttrs_unknownTag/main.vue b/test-workspace/tsc/passedFixtures/vue3_strictTemplate/inheritAttrs_unknownTag/main.vue
new file mode 100644
index 0000000000..e177ec22aa
--- /dev/null
+++ b/test-workspace/tsc/passedFixtures/vue3_strictTemplate/inheritAttrs_unknownTag/main.vue
@@ -0,0 +1,7 @@
+<script setup lang="ts">
+import basic from './basic.vue';
+</script>
+
+<template>
+	<basic />
+</template>