1 files changed, 69 insertions, 0 deletions
diff --git a/third_party/rust/inherent/src/parse.rs b/third_party/rust/inherent/src/parse.rs
new file mode 100644
index 0000000000..92a91f624b
--- /dev/null
+++ b/third_party/rust/inherent/src/parse.rs
@@ -0,0 +1,69 @@
+use proc_macro2::{Span, TokenStream};
+use quote::ToTokens;
+use syn::parse::{Error, Parse, ParseStream, Result};
+use syn::token::Brace;
+use syn::{Attribute, Generics, ImplItem, ItemImpl, Path, Token, Type};
+
+#[derive(Clone)]
+pub struct TraitImpl {
+    pub attrs: Vec<Attribute>,
+    pub defaultness: Option<Token![default]>,
+    pub unsafety: Option<Token![unsafe]>,
+    pub impl_token: Token![impl],
+    pub generics: Generics,
+    pub trait_: Path,
+    pub for_token: Token![for],
+    pub self_ty: Type,
+    pub brace_token: Brace,
+    pub items: Vec<ImplItem>,
+}
+
+impl Parse for TraitImpl {
+    fn parse(input: ParseStream) -> Result<Self> {
+        let imp: ItemImpl = input.parse()?;
+
+        let (trait_, for_token) = match imp.trait_ {
+            Some((_bang_token, trait_, for_token)) => (trait_, for_token),
+            None => {
+                return Err(Error::new(
+                    Span::call_site(),
+                    "must be placed on a trait impl",
+                ))
+            }
+        };
+
+        Ok(TraitImpl {
+            attrs: imp.attrs,
+            defaultness: imp.defaultness,
+            unsafety: imp.unsafety,
+            impl_token: imp.impl_token,
+            generics: imp.generics,
+            trait_,
+            for_token,
+            self_ty: *imp.self_ty,
+            brace_token: imp.brace_token,
+            items: imp.items,
+        })
+    }
+}
+
+impl ToTokens for TraitImpl {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        let imp = self.clone();
+
+        ItemImpl::to_tokens(
+            &ItemImpl {
+                attrs: imp.attrs,
+                defaultness: imp.defaultness,
+                unsafety: imp.unsafety,
+                impl_token: imp.impl_token,
+                generics: imp.generics,
+                trait_: Some((None, imp.trait_, imp.for_token)),
+                self_ty: Box::new(imp.self_ty),
+                brace_token: imp.brace_token,
+                items: imp.items,
+            },
+            tokens,
+        );
+    }
+}