Support skipping only some variants with Zeroize (#112)

Author: daxpedda

CHANGELOG.md

@@ -12,6 +12,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   **Note:** `Clone` is excluded from blanket skipping and can only be used with
   selective skipping to avoid this being a breaking change.
 
+### Fixed
+- Support skipping only some variants with `Zeroize`.
+
 ## [1.3.0] - 2025-04-21
 
 ### Added

src/test/zeroize.rs

@@ -233,6 +233,35 @@ fn fqs() -> Result<()> {
 
 #[test]
 fn enum_skip() -> Result<()> {
+	test_derive(
+		quote! {
+			#[derive_where(Zeroize)]
+			enum Test<T> {
+				A(std::marker::PhantomData<T>),
+				#[derive_where(skip_inner(Zeroize))]
+				B(std::marker::PhantomData<T>),
+			}
+		},
+		quote! {
+			#[automatically_derived]
+			impl <T> ::zeroize::Zeroize for Test<T> {
+				fn zeroize(&mut self) {
+					use ::zeroize::Zeroize;
+
+					match self {
+						Test::A(ref mut __field_0) => {
+							__field_0.zeroize();
+						}
+						Test::B(ref mut __field_0) => { }
+					}
+				}
+			}
+		},
+	)
+}
+
+#[test]
+fn enum_skip_drop() -> Result<()> {
 	test_derive(
 		quote! {
 			#[derive_where(ZeroizeOnDrop)]

src/trait_/zeroize.rs

@@ -112,34 +112,30 @@ impl TraitImpl for Zeroize {
 		trait_: &DeriveTrait,
 		data: &Data,
 	) -> TokenStream {
-		if data.is_empty(**trait_) {
-			TokenStream::new()
-		} else {
-			match data.simple_type() {
-				SimpleType::Struct(fields) | SimpleType::Tuple(fields) => {
-					let trait_path = trait_.path();
-					let self_pattern = fields.self_pattern_mut();
-
-					let body = data
-						.iter_fields(**trait_)
-						.zip(data.iter_self_ident(**trait_))
-						.map(|(field, self_ident)| {
-							if field.attr.zeroize_fqs.0 {
-								quote! { #trait_path::zeroize(#self_ident); }
-							} else {
-								quote! { #self_ident.zeroize(); }
-							}
-						});
-
-					quote! {
-						#self_pattern => {
-							#(#body)*
+		match data.simple_type() {
+			SimpleType::Struct(fields) | SimpleType::Tuple(fields) => {
+				let trait_path = trait_.path();
+				let self_pattern = fields.self_pattern_mut();
+
+				let body = data
+					.iter_fields(**trait_)
+					.zip(data.iter_self_ident(**trait_))
+					.map(|(field, self_ident)| {
+						if field.attr.zeroize_fqs.0 {
+							quote! { #trait_path::zeroize(#self_ident); }
+						} else {
+							quote! { #self_ident.zeroize(); }
 						}
+					});
+
+				quote! {
+					#self_pattern => {
+						#(#body)*
 					}
 				}
-				SimpleType::Unit(_) => TokenStream::new(),
-				SimpleType::Union => unreachable!("unexpected trait for union"),
 			}
+			SimpleType::Unit(_) => TokenStream::new(),
+			SimpleType::Union => unreachable!("unexpected trait for union"),
 		}
 	}
 }