magic anchor
I'm trying to reflect a type:
#[derive(Component, Reflect, FromReflect)]
#[reflect(Component)]
struct Foo(HashMap<Id, X>);
where Id is:
#[derive(Clone, Copy, Hash, PartialEq, Eq, Reflect, FromReflect)]
#[reflect(Hash, PartialEq)]
pub struct Id(usize);
And yet this is panicking in bevy_reflect/src/map.rs:
thread 'main' panicked at 'the given key does not support hashing'
I've checked and my Id type is registered with App. Am I missing something else?
magic anchor
Bumping this thread, since I'm running into this issue again. I abandoned the idea before.
@cerulean dock Hoping you have some ideas here based on this discussion 😄
https://discord.com/channels/691052431525675048/1087255784536154112
I have a really simple type:
#[derive(Clone, Copy, PartialEq, Eq, Reflect, FromReflect)]
#[reflect(Hash)]
pub struct Id(u64);
And I'm trying to store this into a HashMap as keys, but Bevy is just not having it, giving me "the given key does not support hashing" when trying to serialize. I've tried using #[reflect(Hash, PartialEq, Debug)] too, and same thing (the ID type implements Debug manually).
The Id type itself is being perfectly serialized in other places. And I can get around the problem by just storing a HashMap<u64, T>
But I don't get why this isn't working
cerulean dock
It panics at serialization or deserialization?
magic anchor
Serialization
Do I need to do anything besides .register_type::<Id>().register_type::<HashMap<Id, T>>() during build phase?
cerulean dock
Well, generally the only time you get the the given key does not support hashing error is when attempting to insert a dynamic type into a map
I'm guessing there's some part of your code or Bevy's code that's cloning the key before the serialization
Since Reflect::clone_value will often introduce these dynamic types
magic anchor
i can't see where it would do that.
copy pasted snippets from my code:
This is the ID type:
#[derive(Clone, Copy, PartialEq, Eq, Reflect, FromReflect)]
#[reflect(Hash)]
pub struct Tag(u64);
This is my container component:
#[derive(Component, Default, Reflect)]
#[reflect(Component)]
pub struct Layout {
// TODO: This should be a map of tags to enclosures
enclosures: HashMap<u64, Enclosure>,
}
Tag is being registered as such:
app.register_type::<Tag>();
And Layout is being registered as such:
app.register_type::<Layout>()
.register_type::<HashMap<u64, Enclosure>>()
.register_type::<Enclosure>()
The Enclosure type does do dynamic allocation, since it contains a Vec. But that's the value type:
#[derive(Reflect, FromReflect)]
pub struct Enclosure {
entities: Vec<Entity>,
limit: usize,
}
There is no boxing or anything crazy happening
If I change u64 to Tag in the hashmap, I get the panic
cerulean dock
And there are no instances of clone_value or clone_dynamic in your code?
cerulean dock
Oh wait what version is this?
magic anchor
i've learned my lesson to just work around boxed/dynamic types in bevy, since it gave me so much pain, so it's all static
0.10.1
cerulean dock
Oh gotcha
cerulean dock
Essentially we weren't properly handling clone_dynamic for HashMap
It was calling clone_value on the keys but not converting them back to their concrete types using FromReflect
But it should be fixed now (for the 0.11 release in a few weeks)
cerulean dock
Yeah haha it's not you
But if you're able to, I would confirm that 0.11 fixes your issue
If it doesn't there may be some other bug or issue happening that would be nice to address before 0.11
magic anchor
Yah I'll leave a TODO and get around to it when 0.11 rolls out
Oh you mean before 0.11
I'll see if I can upgrade
cerulean dock
Yeah before (if you have time)
Doesn't have to be much, just a verification it's working
Also, quick question: are you using scenes for serialization?
cerulean dock
Okay cool then yeah that should be the issue
