fix(language-core): infer object keys as string if it does not extend string

packages/language-core/types/template-helpers.d.ts

@@ -110,7 +110,7 @@ declare global {
 		: T extends string ? [string, number][]
 		: T extends (infer U)[] ? [U, number][]
 		: T extends Iterable<infer V> ? [V, number][]
-		: [T[keyof T], `${keyof T & (string | number)}`, number][];
+		: [T[keyof T], keyof T extends string ? keyof T : `${keyof T & (string | number)}`, number][];
 	function __VLS_vSlot<S, D extends S>(slot: S, decl?: D): D extends (...args: infer P) => any ? P : any[];
 	function __VLS_asFunctionalDirective<T, ObjectDirective>(
 		dir: T,

test-workspace/tsc/#5927/main.vue

@@ -0,0 +1,23 @@
+<script setup lang="ts">
+import { exactType } from '../shared';
+
+enum EnumA {
+  Foo = 'foo',
+  Bar = 'bar',
+}
+
+const enumKeyRecord: {
+  [key in EnumA]: string;
+} = {
+  [EnumA.Foo]: 'a',
+  [EnumA.Bar]: 'b',
+};
+</script>
+
+<template>
+  <template v-for="(row, rowIndex, index) of enumKeyRecord" :key="rowIndex">
+    {{ exactType(row, {} as string) }}
+    {{ exactType(rowIndex, {} as EnumA) }}
+    {{ exactType(index, {} as number) }}
+  </template>
+</template>

test-workspace/tsc/#5927/tsconfig.json

@@ -0,0 +1,4 @@
+{
+	"extends": "../../tsconfig.base.json",
+	"include": ["**/*"]
+}

test-workspace/tsc/tsconfig.json

@@ -511,6 +511,9 @@
 		{
 			"path": "./#5899/tsconfig.json"
 		},
+		{
+			"path": "./#5927/tsconfig.json"
+		},
 		{
 			"path": "./#625/tsconfig.json"
 		},