Fix issue with reregistering a component's symbol after deletion

distr/flecs.h

@@ -27282,7 +27282,7 @@ struct type_impl {
         // component has not yet been registered, or the component is used
         // across more than one binary), or if the id does not exists in the
         // world (indicating a multi-world application), register it.
-        if (!s_id || (world && !ecs_exists(world, s_id))) {
+        if (!s_id || (world && !ecs_is_alive(world, s_id))) {
             init(s_id ? s_id : id, allow_tag);
 
             ecs_assert(!id || s_id == id, ECS_INTERNAL_ERROR, NULL);
@@ -31188,7 +31188,6 @@ flecs::entity import(world& world) {
     ecs_entity_t m = ecs_lookup_symbol(world, symbol, true, false);
 
     if (!_::type<T>::registered(world)) {
-
         /* Module is registered with world, initialize static data */
         if (m) {
             _::type<T>::init(m, false);

include/flecs/addons/cpp/component.hpp

@@ -185,7 +185,7 @@ struct type_impl {
         // component has not yet been registered, or the component is used
         // across more than one binary), or if the id does not exists in the
         // world (indicating a multi-world application), register it.
-        if (!s_id || (world && !ecs_exists(world, s_id))) {
+        if (!s_id || (world && !ecs_is_alive(world, s_id))) {
             init(s_id ? s_id : id, allow_tag);
 
             ecs_assert(!id || s_id == id, ECS_INTERNAL_ERROR, NULL);

include/flecs/addons/cpp/mixins/module/impl.hpp

@@ -48,7 +48,6 @@ flecs::entity import(world& world) {
     ecs_entity_t m = ecs_lookup_symbol(world, symbol, true, false);
 
     if (!_::type<T>::registered(world)) {
-
         /* Module is registered with world, initialize static data */
         if (m) {
             _::type<T>::init(m, false);

test/cpp/project.json

@@ -1104,7 +1104,8 @@
                 "rename_namespace_longer",
                 "rename_namespace_nested",
                 "rename_reparent_root_module",
-                "no_recycle_after_rename_reparent"
+                "no_recycle_after_rename_reparent",
+                "reimport_after_delete"
             ]
         }, {
             "id": "ImplicitComponents",
@@ -1167,6 +1168,7 @@
                 "reregister_after_reset",
                 "reregister_after_reset_w_namespace",
                 "reregister_namespace",
+                "reregister_after_delete",
                 "implicit_reregister_after_reset",
                 "reregister_after_reset_different_name",
                 "register_short_template",

test/cpp/src/Entity.cpp

@@ -4896,6 +4896,7 @@ void Entity_iter_empty_type(void) {
     int32_t count = 0;
 
     for (auto id : e.type()) {
+        test_assert(id != 0);
         count ++;
     }
 

test/cpp/src/Module.cpp

@@ -528,3 +528,21 @@ void Module_no_recycle_after_rename_reparent(void) {
     test_assert(p == 0);
     test_str(m.name(), "MyModule");
 }
+
+void Module_reimport_after_delete(void) {
+    flecs::world ecs;
+
+    {
+        auto m = ecs.import<Module>();
+        test_assert(m.lookup("Position") == ecs.component<Position>());
+        test_assert(m == ecs.entity<Module>());
+    }
+
+    ecs.entity<Module>().destruct();
+
+    {
+        auto m = ecs.import<Module>();
+        test_assert(m.lookup("Position") == ecs.component<Position>());
+        test_assert(m == ecs.entity<Module>());
+    }
+}

test/cpp/src/World.cpp

@@ -291,6 +291,27 @@ void World_reregister_after_reset_different_name(void) {
     ecs.component<Position>("Velocity");
 }
 
+void World_reregister_after_delete(void) {
+    flecs::world ecs;
+
+    auto c = ecs.component<Position>();
+    test_str(c.name(), "Position");
+    test_str(c.path(), "::Position");
+    test_str(c.symbol(), "Position");
+
+    c.destruct();
+
+    test_assert(!c.is_alive());
+
+    auto d = ecs.component<Position>();
+    test_assert(c == d);
+    test_assert(c.is_alive());
+
+    test_str(c.name(), "Position");
+    test_str(c.path(), "::Position");
+    test_str(c.symbol(), "Position");
+}
+
 void World_register_component_w_reset_in_multithreaded(void) {
     flecs::world ecs;
 

test/cpp/src/main.cpp

@@ -1066,6 +1066,7 @@ void Module_rename_namespace_longer(void);
 void Module_rename_namespace_nested(void);
 void Module_rename_reparent_root_module(void);
 void Module_no_recycle_after_rename_reparent(void);
+void Module_reimport_after_delete(void);
 
 // Testsuite 'ImplicitComponents'
 void ImplicitComponents_add(void);
@@ -1122,6 +1123,7 @@ void World_different_comp_same_name(void);
 void World_reregister_after_reset(void);
 void World_reregister_after_reset_w_namespace(void);
 void World_reregister_namespace(void);
+void World_reregister_after_delete(void);
 void World_implicit_reregister_after_reset(void);
 void World_reregister_after_reset_different_name(void);
 void World_register_short_template(void);
@@ -5558,6 +5560,10 @@ bake_test_case Module_testcases[] = {
     {
         "no_recycle_after_rename_reparent",
         Module_no_recycle_after_rename_reparent
+    },
+    {
+        "reimport_after_delete",
+        Module_reimport_after_delete
     }
 };
 
@@ -5768,6 +5774,10 @@ bake_test_case World_testcases[] = {
         "reregister_namespace",
         World_reregister_namespace
     },
+    {
+        "reregister_after_delete",
+        World_reregister_after_delete
+    },
     {
         "implicit_reregister_after_reset",
         World_implicit_reregister_after_reset
@@ -7002,7 +7012,7 @@ static bake_test_suite suites[] = {
         "Module",
         NULL,
         NULL,
-        22,
+        23,
         Module_testcases
     },
     {
@@ -7023,7 +7033,7 @@ static bake_test_suite suites[] = {
         "World",
         NULL,
         NULL,
-        116,
+        117,
         World_testcases
     },
     {