2 files changed, 36 insertions, 2 deletions
diff --git a/mingling_macros/src/derive/grouped.rs b/mingling_macros/src/derive/grouped.rs
index 307aab6..a00eea1 100644
--- a/mingling_macros/src/derive/grouped.rs
+++ b/mingling_macros/src/derive/grouped.rs
@@ -16,7 +16,11 @@ pub(crate) fn derive_grouped(input: TokenStream) -> TokenStream {
     let expanded = quote! {
         ::mingling::macros::register_type!(#struct_name);
 
-        impl ::mingling::Grouped<#group_ident> for #struct_name {
+        /// SAFETY: This is an internal implementation of the `Grouped` derive macro,
+        /// guaranteeing that the enum value registered by the `register_type!` macro
+        /// is exactly the same as the actual return value,
+        /// which can be confirmed via the `Ident` in the `quote!` block.
+        unsafe impl ::mingling::Grouped<#group_ident> for #struct_name {
             fn member_id() -> #group_ident {
                 #group_ident::#struct_name
             }
@@ -46,7 +50,11 @@ pub fn derive_grouped_serialize(input: TokenStream) -> TokenStream {
 
         ::mingling::macros::register_type!(#struct_name);
 
-        impl ::mingling::Grouped<#group_ident> for #struct_name {
+        /// SAFETY: This is an internal implementation of the `Grouped` derive macro,
+        /// guaranteeing that the enum value registered by the `register_type!` macro
+        /// is exactly the same as the actual return value,
+        /// which can be confirmed via the `Ident` in the `quote!` block.
+        unsafe impl ::mingling::Grouped<#group_ident> for #struct_name {
             fn member_id() -> #group_ident {
                 #group_ident::#struct_name
             }
diff --git a/mingling_macros/src/derive/structural_data.rs b/mingling_macros/src/derive/structural_data.rs
new file mode 100644
index 0000000..acb2f28
--- /dev/null
+++ b/mingling_macros/src/derive/structural_data.rs
@@ -0,0 +1,26 @@
+use proc_macro::TokenStream;
+use quote::quote;
+use syn::{DeriveInput, parse_macro_input};
+
+use crate::get_global_set;
+
+/// Derive macro for `StructuralData`.
+pub(crate) fn derive_structural_data(input: TokenStream) -> TokenStream {
+    let input = parse_macro_input!(input as DeriveInput);
+    let type_name = input.ident;
+
+    // Register in STRUCTURED_TYPES
+    let type_name_str = type_name.to_string();
+    get_global_set(&crate::STRUCTURED_TYPES)
+        .lock()
+        .unwrap()
+        .insert(type_name_str);
+
+    // Generate BOTH the sealed impl AND the StructuralData impl.
+    let expanded = quote! {
+        impl ::mingling::__private::StructuralDataSealed<crate::ThisProgram> for #type_name {}
+        impl ::mingling::__private::StructuralData<crate::ThisProgram> for #type_name {}
+    };
+
+    expanded.into()
+}