Rust 无法使用syn/darling获取字段属性
我正在尝试使用syn/darling板条箱在proc宏中获取字段属性。这是一个MRE 货舱 src/lib.rs src/cat.rs 如果cat.rs的第11行(我用注释标记了它)将被注释, 程序将无错误地编译 这是。 据我所知,这方面存在一些问题 但我不知道如何解决这个问题Rust 无法使用syn/darling获取字段属性,rust,rust-proc-macros,Rust,Rust Proc Macros,我正在尝试使用syn/darling板条箱在proc宏中获取字段属性。这是一个MRE 货舱 src/lib.rs src/cat.rs 如果cat.rs的第11行(我用注释标记了它)将被注释, 程序将无错误地编译 这是。 据我所知,这方面存在一些问题 但我不知道如何解决这个问题 如何在我的StructField::attrs上设置字段attrs?如中所述,您将错过StructField的“forward\u attrs” 例如: #[derive(Clone, Debug, FromField)
如何在我的StructField::attrs上设置字段attrs?如中所述,您将错过StructField的“forward\u attrs” 例如:
#[derive(Clone, Debug, FromField)]
#[darling(forward_attrs(cfg)]
struct StructField {
ident: Option<syn::Ident>,
ty: syn::Type,
vis: syn::Visibility,
// If the line would be commented, all will be fine
attrs: Vec<syn::Attribute>,
}
#[派生(克隆、调试、FromField)]
#[达林(前锋)]
结构域{
标识:选项,
ty:syn::Type,
vis:syn::可见性,
//如果这行会被评论,一切都会好的
属性:Vec,
}
extern crate proc_macro;
extern crate proc_macro2;
mod cat;
use proc_macro::TokenStream;
use syn::DeriveInput;
#[proc_macro_derive(Cat)]
pub fn derive_cat(input: TokenStream) -> TokenStream {
let input = syn::parse_macro_input!(input as DeriveInput);
cat::expand_derive_cat(&input)
}
use darling::{FromField, FromDeriveInput};
use proc_macro::TokenStream;
use quote::{ToTokens, quote};
#[derive(Clone, Debug, FromField)]
struct StructField {
ident: Option<syn::Ident>,
ty: syn::Type,
vis: syn::Visibility,
// If the line would be commented, all will be fine
attrs: Vec<syn::Attribute>,
}
#[derive(Debug, FromDeriveInput)]
#[darling(supports(struct_named))]
struct Cat {
ident: syn::Ident,
data: darling::ast::Data<(), StructField>,
}
impl ToTokens for Cat {
fn to_tokens(&self, out: &mut proc_macro2::TokenStream) {
let tokens = quote!{};
let fields = self.data.clone().take_struct().unwrap();
//dbg!(fields);
out.extend(tokens)
}
}
pub fn expand_derive_cat(input: &syn::DeriveInput) -> TokenStream {
let cat = match Cat::from_derive_input(&input) {
Ok(parsed) => parsed,
Err(e) => return e.write_errors().into(),
};
let tokens = quote! { #cat };
tokens.into()
}
error[E0425]: cannot find value `__fwd_attrs` in this scope
--> src/cat.rs:5:24
|
5 | #[derive(Clone, Debug, FromField)]
| ^^^^^^^^^ not found in this scope
error: aborting due to previous error
For more information about this error, try `rustc --explain E0425`.
error: could not compile `darling_attrs`.
To learn more, run the command again with --verbose.
#[derive(Clone, Debug, FromField)]
#[darling(forward_attrs(cfg)]
struct StructField {
ident: Option<syn::Ident>,
ty: syn::Type,
vis: syn::Visibility,
// If the line would be commented, all will be fine
attrs: Vec<syn::Attribute>,
}