fix(build): retain defineComponent() treeshakability in Rollup

close #8236

Author: yyx990803

packages/runtime-core/src/apiDefineComponent.ts

@@ -279,6 +279,9 @@ export function defineComponent(
   extraOptions?: ComponentOptions
 ) {
   return isFunction(options)
-    ? extend({ name: options.name }, extraOptions, { setup: options })
+    ? // #8326: extend call and options.name access are considered side-effects
+      // by Rollup, so we have to wrap it in a pure-annotated IIFE.
+      /*#__PURE__*/ (() =>
+        extend({ name: options.name }, extraOptions, { setup: options }))()
     : options
 }