[BUG] "No MonoBehaviour in the file" when using the new Assembly Definition "Version Defines"

Hello Unity Team!

When using the new "Version Defines" on Assembly Definition files, any MonoBehaviour put inside a namespace encapsulated inside a compiler conditional will fail to be recognized by Unity as a valid MonoBehaviour.

To reproduce it:

1. Create an Assembly Definition file.
2. In Version Defines, add one item with a symbol that will compile.
3. Create a MonoBehaviour inside a namespace encapsulated by that symbol you just created.
4 Try to add that newly created MonoBehaviour into a GameObject by drag-n-drop, Unity will warn that there is no MonoBehaviour in the file.

I can still add the component via scripting (gameObject.AddComponent<MyComponentInsideANamespace>()).
Also, if I remove the namespace Unity will allow you to add the component through drag-n-drop just fine.

Already made a bug report, case #1159277

 

For those who may cross against that same issue, here is a temporary solution until Unity fix that:

Code (CSharp):

1. #if MY_DEFINE
2. using UnityEngine;
3.  
4. [ExecuteAlways, AddComponentMenu("Scripts/My Behaviour With That Issue")]
5. internal class AddComponentMyBehaviourWithThatIssue : MonoBehaviour
6. {
7.     private void Reset()
8.     {
9.         gameObject.AddComponent<MyBehaviourWithThatIssue>();
10.     }
11.  
12.     private void Update()
13.     {
14.         DestroyImmediate(this);
15.     }
16. }
17. #endif
18.  

Well, not the perfect solution, but I can live with that for now.

 

@brunocoimbra did Unity get back to you about the bug? I can't find any info online. I'm having the same issue in Unity 2019.2.10.

 

Actually they had, here is their reply:

"Hi,

We have investigated this case thoroughly and have fixed it in 2019.3.
In the interests of protecting the stability and features of Unity for users, we will not backport the fix since it was a quite complex change.

To handle this, you could move the namespace definition outside of the #define preprocessor scope.

Harald."