better errors for assoc types in where clauses

1 files changed, 19 insertions, 3 deletions

diff --git a/src/transform.rs b/src/transform.rs
index 676cfd8..b13b7cf 100644
--- a/src/transform.rs
+++ b/src/transform.rs
@@ -141,11 +141,27 @@ pub fn dynamize_function_bounds(
                     }
                 }
 
-                // TODO: return error if predicate_type.bounded_ty contains associated type
+                // just to provide better error messages
+                if let Some(assoc_type) =
+                    iter_type(&predicate_type.bounded_ty).find_map(filter_map_assoc_paths)
+                {
+                    return Err((
+                        assoc_type.span(),
+                        MethodParseError::UnconvertibleAssocTypeInWhereClause,
+                    ));
+                }
 
+                // just to provide better error messages
                 for bound in &mut predicate_type.bounds {
-                    if let TypeParamBound::Trait(_bound) = bound {
-                        // TODO: return error if bound.path contains associated type
+                    if let TypeParamBound::Trait(bound) = bound {
+                        if let Some(assoc_type) =
+                            iter_path(&bound.path).find_map(filter_map_assoc_paths)
+                        {
+                            return Err((
+                                assoc_type.span(),
+                                MethodParseError::UnconvertibleAssocTypeInWhereClause,
+                            ));
+                        }
                     }
                 }
             }