From 85c0c56e0300a3b1f05b3f2f20cb02b6e4a2860d Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Sat, 26 Aug 2023 22:11:55 +0300
Subject: [PATCH] Add static asserts in
 ecs::entity_component::apply/batch_apply to check that all component types
 are different

---
 libs/ecs/include/psemek/ecs/entity_container.hpp | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/libs/ecs/include/psemek/ecs/entity_container.hpp b/libs/ecs/include/psemek/ecs/entity_container.hpp
index c7f76bf3..f23153a5 100644
--- a/libs/ecs/include/psemek/ecs/entity_container.hpp
+++ b/libs/ecs/include/psemek/ecs/entity_container.hpp
@@ -107,6 +107,8 @@ namespace psemek::ecs
 		 *    The function is guaranteed not to visit destroyed entities (unless it did
 		 *    so before the entity was destroyed).
 		 *  An optional query cache can be supplied to speed up iteration.
+		 *  If any two of the passed component types are equal, the call fails with
+		 *    a compilation error.
 		 *  If the query cache wasn't created with the exact sequence of component
 		 *    types, the behavior is undefined.
 		 *  If the function accesses passed components after destroying the
@@ -129,6 +131,8 @@ namespace psemek::ecs
 		 *    except for empty component types (i.e. std::is_empty_v<Component> is true),
 		 *    each having an unspecified non-zero size.
 		 *  An optional query cache can be supplied to speed up iteration.
+		 *  If any two of the passed component types are equal, the call fails with
+		 *    a compilation error.
 		 *  If the query cache wasn't created with the exact sequence of component
 		 *    types, the behavior is undefined.
 		 *  If the function creates or destroyes entities, the behavior is undefined.
@@ -279,6 +283,8 @@ namespace psemek::ecs
 	template <typename ... Components, typename Function>
 	void entity_container::apply(Function && function, query_cache cache)
 	{
+		static_assert(detail::all_different_types_v<Components...>, "all component types must be different");
+
 		if (!cache)
 			cache = this->cache<Components...>();
 
@@ -319,6 +325,8 @@ namespace psemek::ecs
 	template <typename ... Components, typename Function>
 	void entity_container::batch_apply(Function && function, query_cache cache)
 	{
+		static_assert(detail::all_different_types_v<Components...>, "all component types must be different");
+
 		if (!cache)
 			cache = this->cache<Components...>();