fix(compiler-core): should treat attribute key as expression (#4658)

packages/compiler-core/__tests__/transforms/vFor.spec.ts

@@ -638,6 +638,26 @@ describe('compiler: v-for', () => {
         })
       })
     })
+
+    test('template v-for key no prefixing on attribute key', () => {
+      const {
+        node: { codegenNode }
+      } = parseWithForTransform(
+        '<template v-for="item in items" key="key">test</template>',
+        { prefixIdentifiers: true }
+      )
+      const innerBlock = codegenNode.children.arguments[1].returns
+      expect(innerBlock).toMatchObject({
+        type: NodeTypes.VNODE_CALL,
+        tag: FRAGMENT,
+        props: createObjectMatcher({
+          key: {
+            type: NodeTypes.SIMPLE_EXPRESSION,
+            content: 'key'
+          }
+        })
+      })
+    })
   })
 
   describe('codegen', () => {