Fix issue where it wasn't possible to inherit from entity with Relationship trait

Author: SanderMertens

distr/flecs.c

@@ -5296,6 +5296,7 @@ void flecs_bootstrap(
     /* Sync properties of ChildOf and Identifier with bootstrapped flags */
     ecs_add_pair(world, EcsChildOf, EcsOnDeleteTarget, EcsDelete);
     ecs_add_id(world, EcsChildOf, EcsTrait);
+    ecs_add_id(world, EcsIsA, EcsTrait);
     ecs_add_id(world, EcsChildOf, EcsAcyclic);
     ecs_add_id(world, EcsChildOf, EcsTraversable);
     ecs_add_pair(world, EcsChildOf, EcsOnInstantiate, EcsDontInherit);
@@ -39604,7 +39605,7 @@ void flecs_component_record_check_constraints(
             /* Can't use relationship as target */
             if (ecs_has_id(world, tgt, EcsRelationship)) {
                 if (!ecs_id_is_wildcard(rel) && 
-                    !ecs_has_id(world, rel, EcsTrait)) 
+                    !ecs_has_id(world, rel, EcsTrait))
                 {
                     ecs_throw(ECS_CONSTRAINT_VIOLATED, "cannot use '%s' as target"
                         " in pair '%s': '%s' has the Relationship trait",

src/bootstrap.c

@@ -1060,6 +1060,7 @@ void flecs_bootstrap(
     /* Sync properties of ChildOf and Identifier with bootstrapped flags */
     ecs_add_pair(world, EcsChildOf, EcsOnDeleteTarget, EcsDelete);
     ecs_add_id(world, EcsChildOf, EcsTrait);
+    ecs_add_id(world, EcsIsA, EcsTrait);
     ecs_add_id(world, EcsChildOf, EcsAcyclic);
     ecs_add_id(world, EcsChildOf, EcsTraversable);
     ecs_add_pair(world, EcsChildOf, EcsOnInstantiate, EcsDontInherit);

src/storage/component_index.c

@@ -393,7 +393,7 @@ void flecs_component_record_check_constraints(
             /* Can't use relationship as target */
             if (ecs_has_id(world, tgt, EcsRelationship)) {
                 if (!ecs_id_is_wildcard(rel) && 
-                    !ecs_has_id(world, rel, EcsTrait)) 
+                    !ecs_has_id(world, rel, EcsTrait))
                 {
                     ecs_throw(ECS_CONSTRAINT_VIOLATED, "cannot use '%s' as target"
                         " in pair '%s': '%s' has the Relationship trait",

test/core/project.json

@@ -1848,7 +1848,8 @@
                 "value_pair_to_str",
                 "has_value_pair_wildcard",
                 "has_value_pair_any",
-                "target_w_value_pair"
+                "target_w_value_pair",
+                "inherit_relationship_trait"
             ]
         }, {
            "id": "Trigger",

test/core/src/Pairs.c

@@ -3449,3 +3449,16 @@ void Pairs_target_w_value_pair(void) {
 
     ecs_fini(world);
 }
+
+void Pairs_inherit_relationship_trait(void) {
+    ecs_world_t *world = ecs_mini();
+
+    ecs_entity_t base = ecs_new(world);
+    ecs_add_id(world, base, EcsRelationship);
+
+    ecs_entity_t derived = ecs_new_w_pair(world, EcsIsA, base);
+    test_assert(ecs_has_id(world, derived, EcsRelationship));
+
+    ecs_fini(world);
+}
+

test/core/src/main.c

@@ -1786,6 +1786,7 @@ void Pairs_value_pair_to_str(void);
 void Pairs_has_value_pair_wildcard(void);
 void Pairs_has_value_pair_any(void);
 void Pairs_target_w_value_pair(void);
+void Pairs_inherit_relationship_trait(void);
 
 // Testsuite 'Trigger'
 void Trigger_on_add_trigger_before_table(void);
@@ -10171,6 +10172,10 @@ bake_test_case Pairs_testcases[] = {
     {
         "target_w_value_pair",
         Pairs_target_w_value_pair
+    },
+    {
+        "inherit_relationship_trait",
+        Pairs_inherit_relationship_trait
     }
 };
 
@@ -16015,7 +16020,7 @@ static bake_test_suite suites[] = {
         "Pairs",
         NULL,
         NULL,
-        135,
+        136,
         Pairs_testcases
     },
     {