support Self qualified as same trait

6 files changed, 57 insertions, 31 deletions

diff --git a/src/lib.rs b/src/lib.rs
index fc559bc..f8fdde8 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -85,7 +85,8 @@ pub fn dynamize(_attr: TokenStream, input: TokenStream) -> TokenStream {
 
     let mut type_converter = TypeConverter {
         collections: method_attrs.collections,
-        ..TypeConverter::default()
+        assoc_type_conversions: HashMap::new(),
+        trait_ident: original_trait.ident.clone(),
     };
 
     for item in &original_trait.items {
@@ -158,8 +159,8 @@ pub fn dynamize(_attr: TokenStream, input: TokenStream) -> TokenStream {
                     MethodError::Transform(TransformError::QualifiedAssociatedType) => {
                         return abort!(span, "dynamize does not support qualified associated types")
                     }
-                    MethodError::Transform(TransformError::QualifiedSelfAssociatedType) => {
-                        return abort!(span, "dynamize does not support associated types of a qualified Self")
+                    MethodError::Transform(TransformError::SelfQualifiedAsOtherTrait) => {
+                        return abort!(span, "dynamize does not support Self qualified as another trait")
                     }
                     MethodError::UnconvertedAssocType => {
                         return abort!(span, "dynamize does not support associated types here")
diff --git a/src/trait_sig.rs b/src/trait_sig.rs
index 3fb439f..5d8eddf 100644
--- a/src/trait_sig.rs
+++ b/src/trait_sig.rs
@@ -140,6 +140,8 @@ fn bounds_self_and_has_bound_sized(predicate: &WherePredicate) -> bool {
 
 #[cfg(test)]
 mod tests {
+    use std::collections::HashMap;
+
     use quote::{format_ident, quote};
     use syn::{TraitItemMethod, Type};
 
@@ -149,6 +151,14 @@ mod tests {
         transform::{TransformError, TypeConverter},
     };
 
+    fn test_converter() -> TypeConverter<'static> {
+        TypeConverter {
+            assoc_type_conversions: HashMap::new(),
+            collections: HashMap::new(),
+            trait_ident: format_ident!("test"),
+        }
+    }
+
     #[test]
     fn ok_void() {
         let mut type1: TraitItemMethod = syn::parse2(quote! {
@@ -157,7 +167,7 @@ mod tests {
         .unwrap();
 
         assert!(matches!(
-            convert_trait_signature(&mut type1.sig, &Default::default()),
+            convert_trait_signature(&mut type1.sig, &test_converter()),
             Ok(SignatureChanges {
                 return_type: TypeTransform::NoOp,
                 ..
@@ -172,7 +182,7 @@ mod tests {
         })
         .unwrap();
 
-        let mut type_converter = TypeConverter::default();
+        let mut type_converter = test_converter();
         let ident = format_ident!("A");
         let dest_inner = Type::Verbatim(quote! {Example});
         let dest = DestType::Into(&dest_inner);
@@ -195,7 +205,7 @@ mod tests {
         .unwrap();
 
         assert!(matches!(
-            convert_trait_signature(&mut type1.sig, &Default::default()),
+            convert_trait_signature(&mut type1.sig, &test_converter()),
             Err((
                 _,
                 MethodError::Transform(TransformError::AssocTypeWithoutDestType)
@@ -211,7 +221,7 @@ mod tests {
         .unwrap();
 
         assert!(matches!(
-            convert_trait_signature(&mut type1.sig, &Default::default()),
+            convert_trait_signature(&mut type1.sig, &test_converter()),
             Err((_, MethodError::NonDispatchableMethod))
         ));
     }
@@ -224,7 +234,7 @@ mod tests {
         .unwrap();
 
         assert!(matches!(
-            convert_trait_signature(&mut type1.sig, &Default::default()),
+            convert_trait_signature(&mut type1.sig, &test_converter()),
             Err((_, MethodError::NonDispatchableMethod))
         ));
     }
@@ -237,7 +247,7 @@ mod tests {
         .unwrap();
 
         assert!(matches!(
-            convert_trait_signature(&mut type1.sig, &Default::default()),
+            convert_trait_signature(&mut type1.sig, &test_converter()),
             Err((_, MethodError::NonDispatchableMethod))
         ));
     }
@@ -250,7 +260,7 @@ mod tests {
         .unwrap();
 
         assert!(matches!(
-            convert_trait_signature(&mut type1.sig, &Default::default()),
+            convert_trait_signature(&mut type1.sig, &test_converter()),
             Err((_, MethodError::NonDispatchableMethod))
         ));
     }
@@ -263,7 +273,7 @@ mod tests {
         .unwrap();
 
         assert!(matches!(
-            convert_trait_signature(&mut type1.sig, &Default::default()),
+            convert_trait_signature(&mut type1.sig, &test_converter()),
             Err((_, MethodError::Transform(TransformError::UnsupportedType)))
         ));
     }
@@ -276,7 +286,7 @@ mod tests {
         .unwrap();
 
         assert!(matches!(
-            convert_trait_signature(&mut type1.sig, &Default::default()),
+            convert_trait_signature(&mut type1.sig, &test_converter()),
             Err((_, MethodError::Transform(TransformError::UnsupportedType)))
         ));
     }
@@ -289,7 +299,7 @@ mod tests {
         .unwrap();
 
         assert!(matches!(
-            convert_trait_signature(&mut type1.sig, &Default::default()),
+            convert_trait_signature(&mut type1.sig, &test_converter()),
             Err((_, MethodError::Transform(TransformError::UnsupportedType)))
         ));
     }
@@ -302,7 +312,7 @@ mod tests {
         .unwrap();
 
         assert!(matches!(
-            convert_trait_signature(&mut type1.sig, &Default::default()),
+            convert_trait_signature(&mut type1.sig, &test_converter()),
             Err((_, MethodError::Transform(TransformError::UnsupportedType)))
         ));
     }
@@ -315,7 +325,7 @@ mod tests {
         .unwrap();
 
         assert!(matches!(
-            convert_trait_signature(&mut type1.sig, &Default::default()),
+            convert_trait_signature(&mut type1.sig, &test_converter()),
             Err((_, MethodError::AssocTypeInInputs))
         ));
     }
@@ -328,7 +338,7 @@ mod tests {
         .unwrap();
 
         assert!(matches!(
-            convert_trait_signature(&mut type1.sig, &Default::default()),
+            convert_trait_signature(&mut type1.sig, &test_converter()),
             Err((_, MethodError::AssocTypeInInputs))
         ));
     }
@@ -341,7 +351,7 @@ mod tests {
         .unwrap();
 
         assert!(matches!(
-            convert_trait_signature(&mut type1.sig, &Default::default()),
+            convert_trait_signature(&mut type1.sig, &test_converter()),
             Err((_, MethodError::ImplTraitInInputs))
         ));
     }
@@ -354,7 +364,7 @@ mod tests {
         .unwrap();
 
         assert!(matches!(
-            convert_trait_signature(&mut type1.sig, &Default::default()),
+            convert_trait_signature(&mut type1.sig, &test_converter()),
             Err((_, MethodError::Transform(TransformError::UnsupportedType)))
         ));
     }
diff --git a/src/transform.rs b/src/transform.rs
index eed48c4..75138c9 100644
--- a/src/transform.rs
+++ b/src/transform.rs
@@ -14,10 +14,10 @@ use crate::{
     trait_sig::{MethodError, TypeTransform},
 };
 
-#[derive(Default)]
 pub struct TypeConverter<'a> {
     pub assoc_type_conversions: HashMap<Ident, DestType<'a>>,
     pub collections: HashMap<Ident, usize>,
+    pub trait_ident: Ident,
 }
 
 #[derive(Debug)]
@@ -27,7 +27,7 @@ pub enum TransformError {
     ExpectedAtLeastNTypes(usize),
     AssocTypeAfterFirstNTypes(usize, Ident),
     QualifiedAssociatedType,
-    QualifiedSelfAssociatedType,
+    SelfQualifiedAsOtherTrait,
 }
 
 impl TypeConverter<'_> {
@@ -115,7 +115,8 @@ impl TypeConverter<'_> {
         }
 
         if let Type::Path(TypePath {
-            qself: Some(qself), ..
+            path,
+            qself: Some(qself),
         }) = type_
         {
             if let Type::Path(self_path) = qself.ty.as_ref() {
@@ -123,10 +124,22 @@ impl TypeConverter<'_> {
                     if !self_path.path.is_ident("Self") {
                         return Err((self_path.span(), TransformError::QualifiedAssociatedType));
                     }
-                    return Err((
-                        self_path.span(),
-                        TransformError::QualifiedSelfAssociatedType,
-                    ));
+
+                    if qself.position == 1
+                        && path.segments.len() == 2
+                        && path.segments[0].arguments.is_empty()
+                        && path.segments[0].ident == self.trait_ident
+                    {
+                        let ident = &path.segments[1].ident;
+                        let dest_type =
+                            self.assoc_type_conversions.get(ident).ok_or_else(|| {
+                                (ident.span(), TransformError::AssocTypeWithoutDestType)
+                            })?;
+                        *type_ = dest_type.get_dest();
+                        return Ok(dest_type.type_transformation());
+                    }
+
+                    return Err((path.span(), TransformError::SelfQualifiedAsOtherTrait));
                 }
             }
         } else if let Type::Path(TypePath { path, qself: None }) = type_ {
diff --git a/tests/tests.rs b/tests/tests.rs
index e30b0ef..e3df519 100644
--- a/tests/tests.rs
+++ b/tests/tests.rs
@@ -35,6 +35,8 @@ fn it_works() {
         #[allow(clippy::type_complexity)]
         fn test10(&self) -> (Self::A, (Self::A, Self::B), Self::B);
 
+        fn test11(&self) -> <Self as MyTrait>::A;
+
         // fn test9(&self) -> &dyn Iterator<Item = Self::A>;
 
         fn mut1(&mut self) -> Self::A;
diff --git a/ui-tests/src/bin/qualified_self.stderr b/ui-tests/src/bin/qualified_self.stderr
index 1b5f9f9..d8c3a37 100644
--- a/ui-tests/src/bin/qualified_self.stderr
+++ b/ui-tests/src/bin/qualified_self.stderr
@@ -1,5 +1,5 @@
-error: dynamize does not support associated types of a qualified Self
- --> src/bin/qualified_self.rs:7:24
+error: dynamize does not support Self qualified as another trait
+ --> src/bin/qualified_self.rs:7:32
   |
 7 |     fn test(&self) -> <Self as Foo>::X;
-  |                        ^^^^
+  |                                ^^^
diff --git a/ui-tests/src/bin/qualified_self_opt.stderr b/ui-tests/src/bin/qualified_self_opt.stderr
index e032be5..dd99406 100644
--- a/ui-tests/src/bin/qualified_self_opt.stderr
+++ b/ui-tests/src/bin/qualified_self_opt.stderr
@@ -1,5 +1,5 @@
-error: dynamize does not support associated types of a qualified Self
- --> src/bin/qualified_self_opt.rs:7:31
+error: dynamize does not support Self qualified as another trait
+ --> src/bin/qualified_self_opt.rs:7:39
   |
 7 |     fn test(&self) -> Option<<Self as Foo>::X>;
-  |                               ^^^^
+  |                                       ^^^