2 files changed, 27 insertions, 0 deletions
diff --git a/src/ast/ast.c b/src/ast/ast.c
index 0799845..f4922a6 100644
--- a/src/ast/ast.c
+++ b/src/ast/ast.c
@@ -168,6 +168,18 @@ int type_eq(Type *a, Type *b)
     {
         return 0 == strcmp(a->name, b->name);
     }
+    if (a->kind == TYPE_ALIAS)
+    {
+        if (a->alias.is_opaque_alias)
+        {
+            if (b->kind != TYPE_ALIAS || !b->alias.is_opaque_alias)
+            {
+                return 0;
+            }
+            return 0 == strcmp(a->name, b->name);
+        }
+        return type_eq(a->inner, b);
+    }
     if (a->kind == TYPE_POINTER || a->kind == TYPE_ARRAY)
     {
         return type_eq(a->inner, b->inner);
@@ -340,6 +352,8 @@ static char *type_to_string_impl(Type *t)
         }
         return xstrdup(t->name);
     }
+    case TYPE_ALIAS:
+        return xstrdup(t->name);
 
     default:
         return xstrdup("unknown");
@@ -524,6 +538,9 @@ static char *type_to_c_string_impl(Type *t)
     case TYPE_GENERIC:
         return xstrdup(t->name);
 
+    case TYPE_ALIAS:
+        return type_to_c_string(t->inner);
+
     case TYPE_ENUM:
         return xstrdup(t->name);
 
diff --git a/src/ast/ast.h b/src/ast/ast.h
index b272cae..a868bf0 100644
--- a/src/ast/ast.h
+++ b/src/ast/ast.h
@@ -58,6 +58,7 @@ typedef enum
     TYPE_ARRAY,    ///< Fixed size array [N].
     TYPE_FUNCTION, ///< Function pointer or reference.
     TYPE_GENERIC,  ///< Generic type parameter (T).
+    TYPE_ALIAS,    ///< Opaque type alias.
     TYPE_UNKNOWN   ///< Unknown/unresolved type.
 } TypeKind;
 
@@ -84,6 +85,11 @@ typedef struct Type
             int has_drop;     ///< 1 if type implements Drop trait (RAII).
             int has_iterable; ///< 1 if type implements Iterable trait.
         } traits;
+        struct
+        {
+            int is_opaque_alias;
+            char *alias_defined_in_file;
+        } alias;
     };
 } Type;
 
@@ -263,6 +269,8 @@ struct ASTNode
         {
             char *alias;
             char *original_type;
+            int is_opaque;
+            char *defined_in_file;
         } type_alias;
 
         struct
@@ -436,6 +444,8 @@ struct ASTNode
             Attribute *attributes; // Custom attributes
             char **used_structs;   // Names of structs used/mixed-in
             int used_struct_count;
+            int is_opaque;
+            char *defined_in_file; // File where the struct is defined (for privacy check)
         } strct;
 
         struct