From 9f36dfc0e408ff9d4fc63b5a4815bee5d3c1ebb6 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Tue, 22 Aug 2023 23:24:49 +0300
Subject: [PATCH] Make compilation fail if ecs::entity_container::create is
 called with several equal component types

---
 .../psemek/ecs/detail/all_different_types.hpp | 24 +++++++++++++++++++
 .../include/psemek/ecs/entity_container.hpp   |  4 ++++
 2 files changed, 28 insertions(+)
 create mode 100644 libs/ecs/include/psemek/ecs/detail/all_different_types.hpp

diff --git a/libs/ecs/include/psemek/ecs/detail/all_different_types.hpp b/libs/ecs/include/psemek/ecs/detail/all_different_types.hpp
new file mode 100644
index 00000000..27c7a5a9
--- /dev/null
+++ b/libs/ecs/include/psemek/ecs/detail/all_different_types.hpp
@@ -0,0 +1,24 @@
+#pragma once
+
+#include <type_traits>
+
+namespace psemek::ecs::detail
+{
+
+	template <typename ... Ts>
+	struct all_different_types;
+
+	template <>
+	struct all_different_types<>
+		: std::true_type
+	{};
+
+	template <typename T, typename ... Ts>
+	struct all_different_types<T, Ts...>
+		: std::bool_constant<(!std::is_same_v<T, Ts> && ...) && all_different_types<Ts...>::value>
+	{};
+
+	template <typename ... Ts>
+	constexpr bool all_different_types_v = all_different_types<Ts...>::value;
+
+}
diff --git a/libs/ecs/include/psemek/ecs/entity_container.hpp b/libs/ecs/include/psemek/ecs/entity_container.hpp
index a86c7a24..a3c32b1c 100644
--- a/libs/ecs/include/psemek/ecs/entity_container.hpp
+++ b/libs/ecs/include/psemek/ecs/entity_container.hpp
@@ -5,6 +5,7 @@
 #include <psemek/ecs/detail/table_container.hpp>
 #include <psemek/ecs/detail/query_cache_container.hpp>
 #include <psemek/ecs/detail/apply_helper.hpp>
+#include <psemek/ecs/detail/all_different_types.hpp>
 #include <psemek/ecs/entity_accessor.hpp>
 #include <psemek/util/span.hpp>
 
@@ -18,6 +19,7 @@ namespace psemek::ecs
 		// Create an entity with the specified components
 		// NB: equivalent to create() followed by a
 		// series of attach() calls, but faster
+		// All components must be unique
 		template <typename ... Components>
 		entity_handle create(Components && ... components);
 
@@ -57,6 +59,8 @@ namespace psemek::ecs
 	template <typename ... Components>
 	entity_handle entity_container::create(Components && ... components)
 	{
+		static_assert(detail::all_different_types_v<Components...>, "all component types must be different");
+
 		detail::component_uuid_holder<Components...> uuids;
 		detail::component_mask mask = component_index_.make_component_mask(uuids.get());