fix #194

src/entt/entity/registry.hpp

@@ -660,7 +660,7 @@ public:
         assert(valid(entity));
 
         if constexpr(sizeof...(Component) == 1) {
-            return (std::get<1>(pool<Component>())->get(entity), ...);
+            return (std::as_const(*std::get<1>(pool<Component>())).get(entity), ...);
         } else {
             return std::tuple<std::add_const_t<Component> &...>{get<Component>(entity)...};
         }
@@ -730,7 +730,7 @@ public:
         assert(valid(entity));
 
         if constexpr(sizeof...(Component) == 1) {
-            return (std::get<1>(assure<Component>())->try_get(entity), ...);
+            return (std::as_const(*std::get<1>(assure<Component>())).try_get(entity), ...);
         } else {
             return std::tuple<std::add_const_t<Component> *...>{try_get<Component>(entity)...};
         }

test/entt/entity/registry.cpp

@@ -1127,3 +1127,19 @@ TEST(Registry, GetOrAssign) {
     ASSERT_EQ(registry.get<int>(entity), value);
     ASSERT_EQ(registry.get<int>(entity), 3);
 }
+
+TEST(Registry, Constness) {
+    entt::registry<> registry;
+
+    ASSERT_TRUE((std::is_same_v<decltype(registry.get<int>({})), int &>));
+    ASSERT_TRUE((std::is_same_v<decltype(registry.get<int, char>({})), std::tuple<int &, char &>>));
+
+    ASSERT_TRUE((std::is_same_v<decltype(registry.try_get<int>({})), int *>));
+    ASSERT_TRUE((std::is_same_v<decltype(registry.try_get<int, char>({})), std::tuple<int *, char *>>));
+
+    ASSERT_TRUE((std::is_same_v<decltype(std::as_const(registry).get<int>({})), const int &>));
+    ASSERT_TRUE((std::is_same_v<decltype(std::as_const(registry).get<int, char>({})), std::tuple<const int &, const char &>>));
+
+    ASSERT_TRUE((std::is_same_v<decltype(std::as_const(registry).try_get<int>({})), const int *>));
+    ASSERT_TRUE((std::is_same_v<decltype(std::as_const(registry).try_get<int, char>({})), std::tuple<const int *, const char *>>));
+}