Fix Generics Issue with enum_is (Peternator7#305)

strum_macros/src/macros/enum_is.rs

@@ -8,6 +8,7 @@ pub fn enum_is_inner(ast: &DeriveInput) -> syn::Result<TokenStream> {
         Data::Enum(v) => &v.variants,
         _ => return Err(non_enum_error()),
     };
+    let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
 
     let enum_name = &ast.ident;
     let variants: Vec<_> = variants
@@ -35,7 +36,7 @@ pub fn enum_is_inner(ast: &DeriveInput) -> syn::Result<TokenStream> {
         .collect();
 
     Ok(quote! {
-        impl #enum_name {
+        impl #impl_generics #enum_name  #ty_generics #where_clause {
             #(#variants)*
         }
     }

strum_tests/tests/enum_is.rs

@@ -1,7 +1,12 @@
+use std::borrow::Cow;
 use strum::EnumIs;
 
 mod core {} // ensure macros call `::core`
-
+#[derive(EnumIs)]
+enum LifeTimeTest<'a>{
+    One(Cow<'a, str>),
+    Two(&'a str)
+}
 #[derive(EnumIs)]
 enum Foo {
     Unit,
@@ -16,7 +21,15 @@ enum Foo {
     #[allow(dead_code)]
     Disabled,
 }
-
+#[test]
+fn generics_test(){
+    let foo = LifeTimeTest::One(Cow::Borrowed("Hello"));
+    assert!(foo.is_one());
+    let foo = LifeTimeTest::Two("Hello");
+    assert!(foo.is_two());
+    let foo = LifeTimeTest::One(Cow::Owned("Hello".to_string()));
+    assert!(foo.is_one());
+}
 #[test]
 fn simple_test() {
     assert!(Foo::Unit.is_unit());