Macros 如何在一个宏中创建多个项？

我正在尝试创建一个宏，在这样使用时：

foo!()

static x: uint = 5;

fn bar() -> uint { x + 1 }

扩展为两个项，一个静态项和一个函数。大概是这样的：

foo!()

static x: uint = 5;

fn bar() -> uint { x + 1 }

有人向我指出，

MacResult

的

make\u items

方法支持这一点，所以我只需要创建一个正确实现它的类型。我是这样做的：

struct MacItems {
    items: Vec<::std::gc::Gc<Item>>,
}

impl MacResult for MacItems {
    fn make_def(&self) -> Option<::syntax::ext::base::MacroDef> { None }
    fn make_expr(&self) -> Option<::std::gc::Gc<ast::Expr>> { None }
    fn make_pat(&self) -> Option<::std::gc::Gc<ast::Pat>> { None }
    fn make_stmt(&self) -> Option<::std::gc::Gc<ast::Stmt>> { None }

    fn make_items(&self) -> Option<::syntax::util::small_vector::SmallVector<::std::gc::Gc<Item>>> {
        Some(::syntax::util::small_vector::SmallVector::many(self.items.clone()))
    }
}

下面是错误：

test.rs:37:13: 37:57 error: use of moved value: `cx`
test.rs:37     v.push( quote_item!(cx, fn bar() -> uint { x + 1 }).unwrap() );
                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: in expansion of quote_item!
test.rs:37:13: 37:57 note: expansion site
test.rs:36:13: 36:50 note: `cx` moved here because it has type `&mut syntax::ext::base::ExtCtxt<'_>`, which is moved by default (use `ref` to override)
test.rs:36     v.push( quote_item!(cx, static x: uint = 5;).unwrap() );
                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: in expansion of quote_item!
test.rs:36:13: 36:50 note: expansion site
error: aborting due to previous error

test.rs:37:13:37:57错误：使用移动值：`cx`
test.rs:37v.push（quote_item！（cx，fn bar（）->uint{x+1}）.unwrap（））；
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
注：在报价单项目的扩展中！
测试rs:37:13:37:57注：扩展站点
test.rs:36:13:36:50注意：`cx`移到这里是因为它的类型为`&mut syntax:：ext:：base:：ExtCtxt，您需要手动将
cx
重新加载到临时
&mut ExtCtxt
。通常，编译器可以自动插入重新启动，但是
quote.*
宏不会扩展到符合此要求的内容

就是

quote_item!(&mut *cx, ...)