SystemParam Derive fixes

bevyengine · Sep 17, 2021 · 90dfd7f · 90dfd7f
1 parent 42409fc
commit 90dfd7f
Showing 1 changed file with 9 additions and 3 deletions.
diff --git a/crates/bevy_ecs/macros/src/lib.rs b/crates/bevy_ecs/macros/src/lib.rs
@@ -10,7 +10,7 @@ use syn::{
     punctuated::Punctuated,
     token::Comma,
     Data, DataStruct, DeriveInput, Field, Fields, GenericParam, Ident, Index, LitInt, Path, Result,
-    Token,
+    Token, TypeParam,
 };
 
 struct AllTuples {
@@ -361,7 +361,13 @@ pub fn derive_system_param(input: TokenStream) -> TokenStream {
         .collect();
 
     let mut punctuated_generics = Punctuated::<_, Token![,]>::new();
-    punctuated_generics.extend(lifetimeless_generics.iter());
+    punctuated_generics.extend(lifetimeless_generics.iter().map(|g| match g {
+        GenericParam::Type(g) => GenericParam::Type(TypeParam {
+            default: None,
+            ..g.clone()
+        }),
+        _ => panic!(),
+    }));
 
     let mut punctuated_generic_idents = Punctuated::<_, Token![,]>::new();
     punctuated_generic_idents.extend(lifetimeless_generics.iter().map(|g| match g {
@@ -406,7 +412,7 @@ pub fn derive_system_param(input: TokenStream) -> TokenStream {
             }
         }
 
-        impl #impl_generics #path::system::SystemParamFetch<'w, 's> for #fetch_struct_name <(#(<#field_types as #path::system::SystemParam>::Fetch,)*), #punctuated_generic_idents> {
+        impl #impl_generics #path::system::SystemParamFetch<'w, 's> for #fetch_struct_name <(#(<#field_types as #path::system::SystemParam>::Fetch,)*), #punctuated_generic_idents> #where_clause {
             type Item = #struct_name#ty_generics;
             unsafe fn get_param(
                 state: &'s mut Self,