allow same-named method generics if they have same bounds

1 files changed, 23 insertions, 2 deletions

diff --git a/src/lib.rs b/src/lib.rs
index 6e88136..5385181 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,5 +1,7 @@
 #![doc = include_str!("../README.md")]
 
+use std::collections::HashMap;
+
 use proc_macro::TokenStream;
 use proc_macro2::Group;
 use quote::format_ident;
@@ -8,6 +10,7 @@ use quote::quote_spanned;
 use quote::ToTokens;
 use syn::parse_macro_input;
 use syn::punctuated::Punctuated;
+use syn::spanned::Spanned;
 use syn::token::Brace;
 use syn::token::Gt;
 use syn::token::Lt;
@@ -171,6 +174,14 @@ pub fn dynamize(_attr: TokenStream, input: TokenStream) -> TokenStream {
         items: Vec::new(),
     };
 
+    let mut generic_map = HashMap::new();
+
+    for generic in &dyn_trait.generics.params {
+        if let GenericParam::Type(type_param) = generic {
+            generic_map.insert(type_param.ident.clone(), type_param.bounds.clone());
+        }
+    }
+
     for (signature, parsed_method) in objectifiable_methods {
         let mut new_method = TraitItemMethod {
             attrs: Vec::new(),
@@ -235,8 +246,18 @@ pub fn dynamize(_attr: TokenStream, input: TokenStream) -> TokenStream {
             // FUTURE: use Vec::drain_filter once it's stable
             let mut i = 0;
             while i < params.len() {
-                if matches!(params[i], GenericParam::Type(_)) {
-                    dyn_trait.generics.params.push(params.remove(i));
+                if let GenericParam::Type(type_param) = &params[i] {
+                    if let Some(bounds) = generic_map.get(&type_param.ident) {
+                        if *bounds == type_param.bounds {
+                            params.remove(i);
+                            continue;
+                        } else {
+                            return abort!(type_param.span(), "dynamize failure: there exists a same-named method generic with different bounds");
+                        }
+                    } else {
+                        generic_map.insert(type_param.ident.clone(), type_param.bounds.clone());
+                        dyn_trait.generics.params.push(params.remove(i));
+                    }
                 } else {
                     i += 1;
                 }