Feedback NativeHashSet which is built on top of NativeHashMap accepts only unmanaged type

Hello,

As the title says, NativeHashSet is built on top of a NativeHashMap, it's only a wrapper.
NativeHashMap accepts struct type for his generics arguments

So why NativeHashSet doesn't do the same ?

 

NativeHashMap also only accepts unmanaged type IRC.

 

The code doesn't said that

 

Well, it does give runtime error: ArgumentException: TestSystem+MyStruct used in native collection is not blittable, not primitive, or contains a type tagged as NativeContainer

Code (CSharp):

1. using System;
2. using Unity.Burst;
3. using Unity.Collections;
4. using Unity.Entities;
5. using Unity.Jobs;
6. using Unity.Mathematics;
7. using Unity.Transforms;
8. using UnityEngine;
9.  
10. public class TestSystem : SystemBase
11. {
12.     private struct MyStruct : IEquatable<MyStruct>
13.     {
14.         public object o;
15.  
16.         public bool Equals(MyStruct other)
17.         {
18.             return Equals(o, other.o);
19.         }
20.  
21.         public override bool Equals(object obj)
22.         {
23.             return obj is MyStruct other && Equals(other);
24.         }
25.  
26.         public override int GetHashCode()
27.         {
28.             return (o != null ? o.GetHashCode() : 0);
29.         }
30.     }
31.    
32.     protected override void OnUpdate()
33.     {
34.         NativeHashMap<MyStruct, byte> m = new NativeHashMap<MyStruct, byte>(0, Allocator.Temp);
35.     }
36. }
37.  

 

because you using an object inside. Unmanaged means ( in this context with burst compiler) you can't have pointer inside your struct however struct allows pointer. Can be handy when your T argument have a blob reference inside.

 

unmanaged constraint doesn't prevent you from having pointers:
https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/builtin-types/unmanaged-types

 

Seems like an issue with BlobAssetReference<T> itself, for some reason it is not unmanaged

 

indeed curious to have an answer from unity team

 

Bump