From 0113268c3f301b5e25da5b6833b0875e702b8410 Mon Sep 17 00:00:00 2001
From: jngls <awildaudionerd@gmail.com>
Date: Mon, 16 Jun 2025 21:16:51 +0100
Subject: [PATCH] Implement generics, lifetimes, bounds and where clause
 support

---
 enum-display-macro/src/lib.rs |  7 +++++--
 src/lib.rs                    | 37 +++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/enum-display-macro/src/lib.rs b/enum-display-macro/src/lib.rs
index 5dc0c7b..e2803be 100644
--- a/enum-display-macro/src/lib.rs
+++ b/enum-display-macro/src/lib.rs
@@ -30,7 +30,7 @@ fn parse_case_name(case_name: &str) -> Case {
 pub fn derive(input: TokenStream) -> TokenStream {
     // Parse the input tokens into a syntax tree
     let DeriveInput {
-        ident, data, attrs, ..
+        ident, data, attrs, generics, ..
     } = parse_macro_input!(input);
 
     // Should we transform the case of the enum variants?
@@ -82,13 +82,16 @@ pub fn derive(input: TokenStream) -> TokenStream {
         }
     });
 
+    // Copy generics and bounds
+    let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
+
     // #[allow(unused_qualifications)] is needed
     // due to https://github.com/SeedyROM/enum-display/issues/1
     // Possibly related to https://github.com/rust-lang/rust/issues/96698
     let output = quote! {
         #[automatically_derived]
         #[allow(unused_qualifications)]
-        impl ::core::fmt::Display for #ident {
+        impl #impl_generics ::core::fmt::Display for #ident #ty_generics #where_clause {
             fn fmt(&self, f: &mut ::core::fmt::Formatter) -> ::core::fmt::Result {
                 ::core::fmt::Formatter::write_str(
                     f,
diff --git a/src/lib.rs b/src/lib.rs
index 2014389..7ac4ebc 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -67,6 +67,19 @@ mod tests {
         DateOfBirth(u32, u32, u32),
     }
 
+    #[allow(dead_code)]
+    #[derive(EnumDisplay)]
+    enum TestEnumWithGenerics<'a, T: Clone> where T: std::fmt::Display {
+        Name,
+        Address {
+            street: &'a T,
+            city: &'a T,
+            state: &'a T,
+            zip: &'a T,
+        },
+        DateOfBirth(u32, u32, u32),
+    }
+
     #[test]
     fn test_unit_field_variant() {
         assert_eq!(TestEnum::Name.to_string(), "Name");
@@ -117,4 +130,28 @@ mod tests {
             "date-of-birth"
         );
     }
+
+    #[test]
+    fn test_unit_field_variant_with_generics() {
+        assert_eq!(TestEnumWithGenerics::<'_, String>::Name.to_string(), "Name");
+    }
+
+    #[test]
+    fn test_named_fields_variant_with_generics() {
+        assert_eq!(
+            TestEnumWithGenerics::Address {
+                street: &"123 Main St".to_string(),
+                city: &"Any Town".to_string(),
+                state: &"CA".to_string(),
+                zip: &"12345".to_string()
+            }
+            .to_string(),
+            "Address"
+        );
+    }
+
+    #[test]
+    fn test_unnamed_fields_variant_with_generics() {
+        assert_eq!(TestEnumWithGenerics::<'_, String>::DateOfBirth(1, 1, 2000).to_string(), "DateOfBirth");
+    }
 }