#1546 Fix crash when using iter::get_var on chained iterators

Author: SanderMertens

distr/flecs.h

@@ -33207,8 +33207,8 @@ inline flecs::entity iter::get_var(int var_id) const {
  * Get value of a query variable for current result.
  */
 inline flecs::entity iter::get_var(const char *name) const {
-    ecs_query_iter_t *qit = &iter_->priv_.iter.query;
-    const flecs::query_t *q = qit->query;
+    const flecs::query_t *q = iter_->query;
+
     int var_id = ecs_query_find_var(q, name);
     ecs_assert(var_id != -1, ECS_INVALID_PARAMETER, name);
     return flecs::entity(iter_->world, ecs_iter_get_var(iter_, var_id));

include/flecs/addons/cpp/impl/iter.hpp

@@ -95,8 +95,8 @@ inline flecs::entity iter::get_var(int var_id) const {
  * Get value of a query variable for current result.
  */
 inline flecs::entity iter::get_var(const char *name) const {
-    ecs_query_iter_t *qit = &iter_->priv_.iter.query;
-    const flecs::query_t *q = qit->query;
+    const flecs::query_t *q = iter_->query;
+
     int var_id = ecs_query_find_var(q, name);
     ecs_assert(var_id != -1, ECS_INVALID_PARAMETER, name);
     return flecs::entity(iter_->world, ecs_iter_get_var(iter_, var_id));

test/cpp/project.json

@@ -526,6 +526,7 @@
                 "multithread_system_w_query_iter",
                 "multithread_system_w_query_iter_w_iter",
                 "multithread_system_w_query_iter_w_world",
+                "multithread_system_w_get_var",
                 "run_callback",
                 "startup_system",
                 "interval_tick_source",

test/cpp/src/System.cpp

@@ -1856,6 +1856,38 @@ void System_multithread_system_w_query_iter_w_world(void) {
     test_int(p->y, 22);
 }
 
+struct Rel { };
+
+void System_multithread_system_w_get_var(void) {
+    flecs::world world;
+    world.set_threads(4);
+
+    flecs::entity bob = world.entity("bob").add<Position>();
+    flecs::entity alice = world.entity("alice").add<Position>();
+
+    bob.add<Rel>(alice);
+
+    int count = 0;
+
+    world.system<const Position>()
+        .with<Rel>("$other")
+        .term_at(0).src("$other")
+        .multi_threaded()
+        .each([&](flecs::iter &it, size_t row, const Position &pos) {
+            flecs::entity e = it.entity(row);
+            flecs::entity other = it.get_var("other");
+
+            test_assert(e == bob);
+            test_assert(other == alice);
+            
+            count ++;
+        });
+
+    world.progress();
+
+    test_int(count, 1);
+}
+
 void System_run_callback(void) {
     flecs::world world;
 

test/cpp/src/main.cpp

@@ -508,6 +508,7 @@ void System_multithread_system_w_query_each_w_world(void);
 void System_multithread_system_w_query_iter(void);
 void System_multithread_system_w_query_iter_w_iter(void);
 void System_multithread_system_w_query_iter_w_world(void);
+void System_multithread_system_w_get_var(void);
 void System_run_callback(void);
 void System_startup_system(void);
 void System_interval_tick_source(void);
@@ -3405,6 +3406,10 @@ bake_test_case System_testcases[] = {
         "multithread_system_w_query_iter_w_world",
         System_multithread_system_w_query_iter_w_world
     },
+    {
+        "multithread_system_w_get_var",
+        System_multithread_system_w_get_var
+    },
     {
         "run_callback",
         System_run_callback
@@ -7082,7 +7087,7 @@ static bake_test_suite suites[] = {
         "System",
         NULL,
         NULL,
-        73,
+        74,
         System_testcases
     },
     {