From 4cbd826d08f4c00501e467496cce5cb5e03e718a Mon Sep 17 00:00:00 2001
From: Alex Shabalin <alex.shabalin@pm.me>
Date: Tue, 20 Feb 2024 11:03:37 +0100
Subject: [PATCH] Make sure that the type names are unique

---
 .../immer-archive/json/json_with_archive.hpp  | 13 ++++++++
 .../immer-archive/test_special_archive.cpp    | 31 +++++++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/immer/experimental/immer-archive/json/json_with_archive.hpp b/immer/experimental/immer-archive/json/json_with_archive.hpp
index 6d292ef1..9f124ca4 100644
--- a/immer/experimental/immer-archive/json/json_with_archive.hpp
+++ b/immer/experimental/immer-archive/json/json_with_archive.hpp
@@ -142,6 +142,15 @@ inline auto generate_archives_save(auto type_names)
     return archives_save<Storage, Names>{storage};
 }
 
+inline auto are_type_names_unique(auto type_names)
+{
+    auto names_set =
+        hana::fold_left(type_names, hana::make_set(), [](auto set, auto pair) {
+            return hana::insert(set, hana::second(pair));
+        });
+    return hana::length(type_names) == hana::length(names_set);
+}
+
 inline auto generate_archives_load(auto type_names)
 {
     auto storage =
@@ -179,6 +188,10 @@ constexpr bool is_archive_empty(const Archives& archives)
 template <typename T>
 auto to_json_with_archive(const T& serializable)
 {
+    using IsUnique = decltype(detail::are_type_names_unique(
+        get_archives_types(serializable)));
+    static_assert(boost::hana::value<IsUnique>(),
+                  "Archive names for each type must be unique");
     auto archives =
         detail::generate_archives_save(get_archives_types(serializable));
     using Archives = std::decay_t<decltype(archives)>;
diff --git a/test/experimental/immer-archive/test_special_archive.cpp b/test/experimental/immer-archive/test_special_archive.cpp
index ebce79f6..5e40f57c 100644
--- a/test/experimental/immer-archive/test_special_archive.cpp
+++ b/test/experimental/immer-archive/test_special_archive.cpp
@@ -743,3 +743,34 @@ TEST_CASE("Test saving a map that contains the same map")
                 json_str);
     }
 }
+
+TEST_CASE("Test non-unique names in the map")
+{
+    {
+        const auto names = hana::make_map(
+            hana::make_pair(hana::type_c<immer::box<int>>,
+                            BOOST_HANA_STRING("box")),
+            hana::make_pair(hana::type_c<immer::box<std::string>>,
+                            BOOST_HANA_STRING("box"))
+
+        );
+
+        using IsUnique =
+            decltype(immer_archive::detail::are_type_names_unique(names));
+        static_assert(boost::hana::value<IsUnique>() == false,
+                      "Detect non-unique names");
+    }
+    {
+        const auto names = hana::make_map(
+            hana::make_pair(hana::type_c<immer::box<int>>,
+                            BOOST_HANA_STRING("box_1")),
+            hana::make_pair(hana::type_c<immer::box<std::string>>,
+                            BOOST_HANA_STRING("box_2"))
+
+        );
+
+        using IsUnique =
+            decltype(immer_archive::detail::are_type_names_unique(names));
+        static_assert(boost::hana::value<IsUnique>(), "Names are unique");
+    }
+}