Resolve useless_conversion clippy lint

    warning: useless conversion to the same type: `syn::Attribute`
      --> src/derive.rs:34:21
       |
    34 |            .into_iter()
       |   _____________________^
       |  |_____________________|
    35 | ||         .map(std::convert::Into::into)
       | ||______________________________________^
    36 | |          .collect();
       | |_________- help: consider removing
       |
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#useless_conversion
       = note: `-W clippy::useless-conversion` implied by `-W clippy::all`
       = help: to override `-W clippy::all` add `#[allow(clippy::useless_conversion)]`

src/derive.rs

@@ -29,12 +29,6 @@ fn derive2(input: TokenStream, run: fn(Execution)) -> TokenStream {
 }
 
 fn syn_to_type(input: DeriveInput) -> Type {
-    let attrs: Vec<_> = input
-        .attrs
-        .into_iter()
-        .map(std::convert::Into::into)
-        .collect();
-
     Type(TypeNode::DataStructure {
         name: Ident::from(input.ident),
         generics: Generics::syn_to_generics(input.generics),
@@ -50,7 +44,7 @@ fn syn_to_type(input: DeriveInput) -> Type {
                             element: Type::syn_to_type(field.ty),
                         })
                         .collect(),
-                    attrs,
+                    attrs: input.attrs,
                 })),
                 syn::Fields::Unnamed(fields) => Data::Struct(Struct::Tuple(TupleStruct {
                     fields: fields
@@ -63,15 +57,15 @@ fn syn_to_type(input: DeriveInput) -> Type {
                             element: Type::syn_to_type(field.ty),
                         })
                         .collect(),
-                    attrs,
+                    attrs: input.attrs,
                 })),
-                syn::Fields::Unit => Data::Struct(Struct::Unit(UnitStruct { attrs })),
+                syn::Fields::Unit => Data::Struct(Struct::Unit(UnitStruct { attrs: input.attrs })),
             },
             syn::Data::Enum(data) => {
                 // FIXME convert enum variants
                 Data::Enum(Enum {
                     variants: Vec::new(),
-                    attrs,
+                    attrs: input.attrs,
                 })
             }
             syn::Data::Union(_) => unimplemented!("union"),