New upstream version 1.70.0+dfsg1

[rustc.git] / compiler / rustc_macros / src / type_foldable.rs

diff --git a/compiler/rustc_macros/src/type_foldable.rs b/compiler/rustc_macros/src/type_foldable.rs
index 388e254cd64530fe82b7cd9f043c7a59957fa360..5ee4d8793135ca8865982460f621012f015edd27 100644 (file)
--- a/compiler/rustc_macros/src/type_foldable.rs
+++ b/compiler/rustc_macros/src/type_foldable.rs
@@ -1,5 +1,5 @@
 use quote::{quote, ToTokens};
-use syn::{parse_quote, Attribute, Meta, NestedMeta};
+use syn::parse_quote;
 
 pub fn type_foldable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
     if let syn::Data::Union(_) = s.ast().data {
@@ -17,21 +17,20 @@ pub fn type_foldable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::
         vi.construct(|_, index| {
             let bind = &bindings[index];
 
+            let mut fixed = false;
+
             // retain value of fields with #[type_foldable(identity)]
-            let fixed = bind
-                .ast()
-                .attrs
-                .iter()
-                .map(Attribute::parse_meta)
-                .filter_map(Result::ok)
-                .flat_map(|attr| match attr {
-                    Meta::List(list) if list.path.is_ident("type_foldable") => list.nested,
-                    _ => Default::default(),
-                })
-                .any(|nested| match nested {
-                    NestedMeta::Meta(Meta::Path(path)) => path.is_ident("identity"),
-                    _ => false,
+            bind.ast().attrs.iter().for_each(|x| {
+                if !x.path().is_ident("type_foldable") {
+                    return;
+                }
+                let _ = x.parse_nested_meta(|nested| {
+                    if nested.path.is_ident("identity") {
+                        fixed = true;
+                    }
+                    Ok(())
                 });
+            });
 
             if fixed {
                 bind.to_token_stream()