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我的目标是编写一个简单的属性 proc 宏,可用于注释函数并打印其参数。

例子:

#[print_arguments]
fn add(a:u64, b:u64) -> u64 {
   a + b
}

使用引号我可以在范围内插入标记并使用syn解析 rust 代码片段。所以我尝试了以下方法:

#[proc_macro_attribute]
pub fn print_arguments(_: TokenStream, item: TokenStream) -> TokenStream {
    let fn_type = parse_macro_input!(item as ItemFn);
    let signature = fn_type.sig;
    let ident = signature.ident;
    let arguments = signature.inputs;
    let return_type = signature.output;

    let mut args = arguments.iter();
    let fn_arg = args.next().expect("msg");

    let block = fn_type.block;

    TokenStream::from(quote! {
        fn #ident ( #arguments ) #return_type {
            println!("enhanced function {:?}", #(#args)*); // this one seems wrong, as it would iterate over FnArg, which is an enum. 
            #block
        }
    })
}

是否有可能访问 FnArg 标识符(标识符)?

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