types/description: add equality operator

types/description.hpp

@@ -36,6 +36,13 @@ namespace cruft::types {
         std::size_t width;
     };
 
+    constexpr bool
+    operator== (description const &a, description const &b) noexcept
+    {
+        return a.category == b.category &&
+               a.width    == b.width;
+    }
+
 
     //-------------------------------------------------------------------------
     template <typename T>