1 files changed, 12 insertions, 1 deletions
diff --git a/include/elna/boot/symbol.h b/include/elna/boot/symbol.h
index 1caba83..0c1026d 100644
--- a/include/elna/boot/symbol.h
+++ b/include/elna/boot/symbol.h
@@ -40,6 +40,7 @@ namespace elna::boot
     struct slice_type;
     struct procedure_type;
     struct enumeration_type;
+    struct extern_type;
 
     /**
      * Represents a type stored in the symbol table.
@@ -59,7 +60,8 @@ namespace elna::boot
             std::shared_ptr<array_type>,
             std::shared_ptr<slice_type>,
             std::shared_ptr<procedure_type>,
-            std::shared_ptr<enumeration_type>
+            std::shared_ptr<enumeration_type>,
+            std::shared_ptr<extern_type>
         >;
         Payload payload;
 
@@ -188,6 +190,15 @@ namespace elna::boot
         explicit enumeration_type(const std::vector<std::string>& members);
     };
 
+    /**
+     * An opaque type declared with \c type T = extern.  The representation is
+     * unknown, so the type has no properties and can only be used behind a
+     * pointer.
+     */
+    struct extern_type
+    {
+    };
+
     class type_info;
     class procedure_info;
     class variable_info;