Iterate all entities in the world in C++?

[robo-todd]

I need to add customized serialization support for our flecs-based system and one of the functions is basically a variation on ecs_world_to_json_buf() but for our serialization approach. I would prefer to do this in C++. The function is invoked by a system during the progress update if that is relevant.

I feel like I'm stupid because nothing that I try for this works. I appear to only end up with one of two options:

• The iteration / each produces absolutely nothing.
• It crashes in some bizarre way (have tried dozens of permutations).

I have even tried basically cutting/pasting the parts of ecs_world_to_json_buf() in C into the function that gets called and this also simply crashes with a null table.

        ecs_query_desc_t query_desc = {0};
        query_desc.terms[0].id = ecs_pair(EcsChildOf, EcsFlecs);
        query_desc.terms[0].oper = EcsNot;
        query_desc.terms[0].src.id = EcsSelf | EcsUp;
        query_desc.flags = EcsQueryMatchDisabled | EcsQueryMatchPrefab;
        ecs_query_t *qq = ecs_query_init(self.world().world_, &query_desc);

        if (qq != nullptr) {
            spdlog::info("Iterating query."); /* This prints out ... */
            ecs_iter_t it = ecs_query_iter(self.world().world_, qq);  /* Crashes right here << */
            while (ecs_each_next(&it)) {
                spdlog::info("Iterator Count {}", it.count);
                for (int ii = 0; ii < it.count; ii++) {
                    spdlog::info("Entity: {}", ecs_get_name(self.world().world_, it.entities[ii]));
                }
            }
        }

Crashes with:

ecs_table_count (table=table@entry=0x0) at /<path>/src/flecs/src/storage/table.c:2437 2437 return table->data.count;

So I feel like I'm really missing some understanding. I would have thought (for example) that this would have just worked:

world.each([](flecs::entity id) { // Iterate everything here. });

At least some variation of the above?

But it seems like nothing works and I'm reading/reverse-engineering source code and wondering if there is some basic incantation that will "iterate the world" for these utility/meta style functions in a nice way in C++?