support boxed Iterator in Option

1 files changed, 9 insertions, 8 deletions

diff --git a/src/parse_assoc_type.rs b/src/parse_assoc_type.rs
index 85f3723..048e58c 100644
--- a/src/parse_assoc_type.rs
+++ b/src/parse_assoc_type.rs
@@ -1,7 +1,7 @@
-use proc_macro2::Span;
+use proc_macro2::{Span, TokenStream};
 use quote::{quote, ToTokens};
 use syn::spanned::Spanned;
-use syn::{GenericArgument, Ident, Path, PathArguments, PathSegment, TraitItemType, Type};
+use syn::{GenericArgument, Ident, PathArguments, PathSegment, TraitItemType, Type};
 
 use crate::match_assoc_type;
 use crate::parse_trait_sig::TypeTransform;
@@ -16,16 +16,16 @@ pub enum AssocTypeParseError {
 
 #[derive(Debug, Clone)]
 pub struct BoxType {
-    trait_name: Path,
-    placeholder_lifetime: bool,
+    pub inner: TokenStream,
+    pub placeholder_lifetime: bool,
 }
 
 impl ToTokens for BoxType {
     fn to_tokens(&self, tokens: &mut proc_macro2::TokenStream) {
-        let path = &self.trait_name;
+        let inner = &self.inner;
         match self.placeholder_lifetime {
-            true => tokens.extend(quote! {Box<dyn #path + '_>}),
-            false => tokens.extend(quote! {Box<dyn #path>}),
+            true => tokens.extend(quote! {Box<#inner + '_>}),
+            false => tokens.extend(quote! {Box<#inner>}),
         }
     }
 }
@@ -79,10 +79,11 @@ pub fn parse_assoc_type(
                 }
             }
         }
+        let path = &bound.path;
         return Ok((
             &assoc_type.ident,
             DestType::Box(BoxType {
-                trait_name: bound.path.clone(),
+                inner: quote! {dyn #path},
                 placeholder_lifetime: !lifetime_bounds(&assoc_type.bounds)
                     .any(|l| l.ident == "static"),
             }),