Fix derive Data when type param bounds are defined

CHANGELOG.md

@@ -27,7 +27,9 @@ You can find its changes [documented below](#060---2020-06-01).
 - macOS: Timers not firing during modal loop. ([#1028] by [@xStrom])
 - GTK: Directory selection now properly ignores file filters. ([#957] by [@xStrom])
 - GTK: Don't crash when receiving an external command while a file dialog is visible. ([#1043] by [@jneem])
+- Fix derive `Data` when type param bounds are defined ([#1058] by [@chris-zen])
 - Ensure that `update` is called after all commands. ([#1062] by [@jneem])
+- Fix derive `Data` when type param bounds are defined ([#1058] by [@chris-zen])
 
 ### Visual
 
@@ -236,11 +238,9 @@ Last release without a changelog :(
 [@jrmuizel]: https://github.com/jrmuizel
 [@scholtzan]: https://github.com/scholtzan
 [@covercash2]: https://github.com/covercash2
-<<<<<<< HEAD
 [@raphlinus]: https://github.com/raphlinus
-=======
 [@binomial0]: https://github.com/binomial0
->>>>>>> master
+[@chris-zen]: https://github.com/chris-zen
 
 [#599]: https://github.com/linebender/druid/pull/599
 [#611]: https://github.com/linebender/druid/pull/611
@@ -347,6 +347,7 @@ Last release without a changelog :(
 [#1049]: https://github.com/linebender/druid/pull/1049
 [#1050]: https://github.com/linebender/druid/pull/1050
 [#1054]: https://github.com/linebender/druid/pull/1054
+[#1058]: https://github.com/linebender/druid/pull/1058
 [#1062]: https://github.com/linebender/druid/pull/1062
 
 [Unreleased]: https://github.com/linebender/druid/compare/v0.6.0...master

druid-derive/src/data.rs

@@ -36,10 +36,10 @@ fn derive_struct(
     input: &syn::DeriveInput,
     s: &DataStruct,
 ) -> Result<proc_macro2::TokenStream, syn::Error> {
-    let generics_bounds = generics_bounds(&input.generics);
-    let generics = &input.generics;
+    let ident = &input.ident;
+    let impl_generics = generics_bounds(&input.generics);
+    let (_, ty_generics, where_clause) = &input.generics.split_for_impl();
 
-    let ty = &input.ident;
     let fields = Fields::parse_ast(&s.fields)?;
 
     let diff = if fields.len() > 0 {
@@ -54,7 +54,7 @@ fn derive_struct(
     };
 
     let res = quote! {
-        impl<#generics_bounds> druid::Data for #ty #generics {
+        impl<#impl_generics> ::druid::Data for #ident #ty_generics #where_clause {
             fn same(&self, other: &Self) -> bool {
                 #diff
             }
@@ -80,14 +80,13 @@ fn derive_enum(
     input: &syn::DeriveInput,
     s: &DataEnum,
 ) -> Result<proc_macro2::TokenStream, syn::Error> {
-    let ty = &input.ident;
+    let ident = &input.ident;
+    let impl_generics = generics_bounds(&input.generics);
+    let (_, ty_generics, where_clause) = &input.generics.split_for_impl();
 
     if is_c_style_enum(&s) {
-        let generics_bounds = generics_bounds(&input.generics);
-        let generics = &input.generics;
-
         let res = quote! {
-            impl<#generics_bounds> ::druid::Data for #ty #generics {
+            impl<#impl_generics> ::druid::Data for #ident #ty_generics #where_clause {
                 fn same(&self, other: &Self) -> bool { self == other }
             }
         };
@@ -132,7 +131,7 @@ fn derive_enum(
                     .collect();
 
                 Ok(quote! {
-                    (#ty :: #variant { #( #lefts ),* }, #ty :: #variant { #( #rights ),* }) => {
+                    (#ident :: #variant { #( #lefts ),* }, #ident :: #variant { #( #rights ),* }) => {
                         #( #tests )&&*
                     }
                 })
@@ -148,24 +147,21 @@ fn derive_enum(
 
                 if fields.iter().filter(|field| !field.ignore).count() > 0 {
                     Ok(quote! {
-                        ( #ty :: #variant( #(#vars_left),* ),  #ty :: #variant( #(#vars_right),* )) => {
+                        ( #ident :: #variant( #(#vars_left),* ),  #ident :: #variant( #(#vars_right),* )) => {
                             #( #tests )&&*
                         }
                     })
                 } else {
                     Ok(quote! {
-                       ( #ty :: #variant ,  #ty :: #variant ) => { true }
+                        ( #ident :: #variant ,  #ident :: #variant ) => { true }
                     })
                 }
             }
         })
         .collect::<Result<Vec<proc_macro2::TokenStream>, syn::Error>>()?;
 
-    let generics_bounds = generics_bounds(&input.generics);
-    let generics = &input.generics;
-
     let res = quote! {
-        impl<#generics_bounds> ::druid::Data for #ty #generics {
+        impl<#impl_generics> ::druid::Data for #ident #ty_generics #where_clause {
             fn same(&self, other: &Self) -> bool {
                 match (self, other) {
                     #( #cases ),*
@@ -182,7 +178,15 @@ fn generics_bounds(generics: &syn::Generics) -> proc_macro2::TokenStream {
     let res = generics.params.iter().map(|gp| {
         use syn::GenericParam::*;
         match gp {
-            Type(ty) => quote_spanned!(ty.span()=> #ty : ::druid::Data),
+            Type(ty) => {
+                let ident = &ty.ident;
+                let bounds = &ty.bounds;
+                if bounds.is_empty() {
+                    quote_spanned!(ty.span()=> #ident : ::druid::Data)
+                } else {
+                    quote_spanned!(ty.span()=> #ident : #bounds + ::druid::Data)
+                }
+            }
             Lifetime(lf) => quote!(#lf),
             Const(cst) => quote!(#cst),
         }

druid-derive/tests/data.rs

@@ -30,6 +30,26 @@ struct MultiFieldStruct {
     c: String,
 }
 
+trait UserTrait {}
+
+#[derive(Clone, Data)]
+struct TypeParamForUserTraitStruct<T: UserTrait + Data> {
+    a: T,
+}
+
+#[derive(Clone, Data)]
+struct TypeParamForUserTraitWithWhereClauseStruct<T>
+where
+    T: UserTrait,
+{
+    b: T,
+}
+
+#[derive(Clone, Data)]
+enum TypeParamForUserTraitAndLifetimeEnum<T: UserTrait + 'static> {
+    V1(T),
+}
+
 #[test]
 fn test_data_derive_same() {
     let plain = PlainStruct;
@@ -70,4 +90,27 @@ fn test_data_derive_same() {
             c: "Fail".to_string()
         })
     );
+
+    #[derive(Clone, Data)]
+    struct Value(u32);
+
+    impl UserTrait for Value {}
+
+    let v = TypeParamForUserTraitStruct { a: Value(1) };
+    assert!(v.same(&v));
+    assert_eq!(false, v.same(&TypeParamForUserTraitStruct { a: Value(2) }));
+
+    let v = TypeParamForUserTraitWithWhereClauseStruct { b: Value(3) };
+    assert!(v.same(&v));
+    assert_eq!(
+        false,
+        v.same(&TypeParamForUserTraitWithWhereClauseStruct { b: Value(6) })
+    );
+
+    let v = TypeParamForUserTraitAndLifetimeEnum::V1(Value(10));
+    assert!(v.same(&v));
+    assert_eq!(
+        false,
+        v.same(&TypeParamForUserTraitAndLifetimeEnum::V1(Value(12)))
+    );
 }