Better type for integrals or enumerations for id variant.

README.md

@@ -472,7 +472,9 @@ using serialize_id = zpp::bits::id<"v1::person"_sha256, 4>; // First 4 bytes of
 
 The type is then converted to bytes at compile time using (... wait for it) `zpp::bits::out`
 at compile time, so as long as your literal type is serializable according to the above,
-you can use it as a serialization id.
+you can use it as a serialization id. The id is serialized to `std::array<std::byte, N>` however
+for 1, 2, 4, and 8 bytes its underlying type is `std::byte` `std::uint16_t`, `std::uin32_t` and
+`std::uint64_t` respectively for ease of use and efficiency.
 
 * If you want to serialize the variant without an id, or if you know that a variant is going to
 have a particular ID upon deserialize, you may do it using `zpp::bits::known_id` to wrap your variant:
@@ -485,6 +487,8 @@ in(zpp::bits::known_id<"v2::person"_sha256, 4>(v));
 
 // When deserializing you can pass the id as function parameter, to be able
 // to use outside of compile time context. `id_v` stands for "id value".
+// In our case 4 bytes translates to a plain std::uint32_t, so any dynamic
+// integer could fit as the first parameter to `known_id` below.
 in(zpp::bits::known_id(zpp::bits::id_v<"v2::person"_sha256, 4>, v));
 ```
 

zpp_bits.h

@@ -1767,7 +1767,13 @@ constexpr auto known_id(Variant && variant)
 template <typename Id, concepts::variant Variant>
 struct known_dynamic_id_variant
 {
-    constexpr explicit known_dynamic_id_variant(Variant & variant, Id & id) :
+    using id_type =
+        std::conditional_t<std::is_integral_v<std::remove_cvref_t<Id>> ||
+                               std::is_enum_v<std::remove_cvref_t<Id>>,
+                           std::remove_cvref_t<Id>,
+                           Id &>;
+
+    constexpr explicit known_dynamic_id_variant(Variant & variant, id_type id) :
         variant(variant),
         id(id)
     {
@@ -1779,7 +1785,7 @@ struct known_dynamic_id_variant
     }
 
     Variant & variant;
-    Id & id;
+    id_type id;
 };
 
 template <typename Id, typename Variant>