*: added missing messages to static asserts

src/entt/container/dense_map.hpp

@@ -263,7 +263,7 @@ class dense_map {
 
     using node_type = internal::dense_map_node<Key, Type>;
     using alloc_traits = typename std::allocator_traits<Allocator>;
-    static_assert(std::is_same_v<typename alloc_traits::value_type, std::pair<const Key, Type>>);
+    static_assert(std::is_same_v<typename alloc_traits::value_type, std::pair<const Key, Type>>, "Invalid value type");
     using sparse_container_type = std::vector<std::size_t, typename alloc_traits::template rebind_alloc<std::size_t>>;
     using packed_container_type = std::vector<node_type, typename alloc_traits::template rebind_alloc<node_type>>;
 

src/entt/container/dense_set.hpp

@@ -231,7 +231,7 @@ class dense_set {
 
     using node_type = std::pair<std::size_t, Type>;
     using alloc_traits = std::allocator_traits<Allocator>;
-    static_assert(std::is_same_v<typename alloc_traits::value_type, Type>);
+    static_assert(std::is_same_v<typename alloc_traits::value_type, Type>, "Invalid value type");
     using sparse_container_type = std::vector<std::size_t, typename alloc_traits::template rebind_alloc<std::size_t>>;
     using packed_container_type = std::vector<node_type, typename alloc_traits::template rebind_alloc<node_type>>;
 

src/entt/entity/sparse_set.hpp

@@ -171,7 +171,7 @@ enum class deletion_policy : std::uint8_t {
 template<typename Entity, typename Allocator>
 class basic_sparse_set {
     using alloc_traits = std::allocator_traits<Allocator>;
-    static_assert(std::is_same_v<typename alloc_traits::value_type, Entity>);
+    static_assert(std::is_same_v<typename alloc_traits::value_type, Entity>, "Invalid value type");
     using sparse_container_type = std::vector<typename alloc_traits::pointer, typename alloc_traits::template rebind_alloc<typename alloc_traits::pointer>>;
     using packed_container_type = std::vector<Entity, Allocator>;
     using entity_traits = entt_traits<Entity>;

src/entt/entity/storage.hpp

@@ -235,7 +235,7 @@ class basic_storage: public basic_sparse_set<Entity, typename std::allocator_tra
     static_assert(std::is_move_constructible_v<Type> && std::is_move_assignable_v<Type>, "The type must be at least move constructible/assignable");
 
     using alloc_traits = std::allocator_traits<Allocator>;
-    static_assert(std::is_same_v<typename alloc_traits::value_type, Type>);
+    static_assert(std::is_same_v<typename alloc_traits::value_type, Type>, "Invalid value type");
     using underlying_type = basic_sparse_set<Entity, typename alloc_traits::template rebind_alloc<Entity>>;
     using container_type = std::vector<typename alloc_traits::pointer, typename alloc_traits::template rebind_alloc<typename alloc_traits::pointer>>;
     using comp_traits = component_traits<Type>;
@@ -748,7 +748,7 @@ template<typename Entity, typename Type, typename Allocator>
 class basic_storage<Entity, Type, Allocator, std::enable_if_t<ignore_as_empty_v<Type>>>
     : public basic_sparse_set<Entity, typename std::allocator_traits<Allocator>::template rebind_alloc<Entity>> {
     using alloc_traits = std::allocator_traits<Allocator>;
-    static_assert(std::is_same_v<typename alloc_traits::value_type, Type>);
+    static_assert(std::is_same_v<typename alloc_traits::value_type, Type>, "Invalid value type");
     using underlying_type = basic_sparse_set<Entity, typename alloc_traits::template rebind_alloc<Entity>>;
     using comp_traits = component_traits<Type>;
 

src/entt/signal/sigh.hpp

@@ -58,7 +58,7 @@ class sigh<Ret(Args...), Allocator> {
     friend class sink<sigh<Ret(Args...), Allocator>>;
 
     using alloc_traits = std::allocator_traits<Allocator>;
-    static_assert(std::is_same_v<typename alloc_traits::value_type, Ret (*)(Args...)>);
+    static_assert(std::is_same_v<typename alloc_traits::value_type, Ret (*)(Args...)>, "Invalid value type");
     using container_type = std::vector<delegate<Ret(Args...)>, typename alloc_traits::template rebind_alloc<delegate<Ret(Args...)>>>;
 
 public: