1 files changed, 28 insertions, 1 deletions
diff --git a/src/parse_attrs.rs b/src/parse_attrs.rs
index 03b5377..d9725ff 100644
--- a/src/parse_attrs.rs
+++ b/src/parse_attrs.rs
@@ -1,4 +1,4 @@
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
 
 use proc_macro2::{Group, TokenStream};
 use quote::quote;
@@ -33,6 +33,21 @@ pub struct TraitAttrs {
     pub blanket_impl_attrs: Vec<TokenStream>,
     pub dyn_trait_attrs: Vec<TokenStream>,
     pub collections: HashMap<Ident, usize>,
+    pub dynamized_supertraits: HashSet<Ident>,
+}
+
+struct Dynamized {
+    ident: Ident,
+}
+
+impl Parse for Dynamized {
+    fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
+        let inner;
+        parenthesized!(inner in input);
+        Ok(Self {
+            ident: inner.parse()?,
+        })
+    }
 }
 
 impl TraitAttrs {
@@ -84,6 +99,18 @@ impl TraitAttrs {
                         ),
                     ));
                 }
+            } else if attrs[i].path.is_ident("dynamized") {
+                let attr = attrs.remove(i);
+                let dynamized: Dynamized = syn::parse2(attr.tokens)?;
+                let span = dynamized.ident.span();
+
+                if !parsed.dynamized_supertraits.insert(dynamized.ident) {
+                    // FUTURE: relax to warning once proc_macro::Diagnostic is stable
+                    return Err(Error::new(
+                        span,
+                        format_args!("dynamized attribute is defined multiple times"),
+                    ));
+                }
             } else {
                 i += 1;
             }