koobas.hobune.stream
Confusing Transitive Assembly References
TL;DR
How do you write managed plugins in Unity 2019.2+ that reference types defined in Unity Packages, particularly those that used to be defined in UnityEngine.UI.dll, like ScrollRect?
MORE INFO
I have been trying to create two managed plugins (assemblies) to pull out common logic for my Unity projects: UnityUtil.dll, which defines some common types, and UnityUtil.Editor.dll which references and defines custom inspectors for some of the types in UnityUtil. Both assemblies referenced the UnityEngine.dll and UnityEngine.UI.dll assemblies stored in Program Files/, and UnityUtil.Editor also referenced UnityEditor.dll. After upgrading to Unity 2019.2, UnityEngine.UI.dll is no longer present in Program Files/; instead, it is part of the com.unity.ugui Unity Package, and thus ends up in Library/ScriptAssemblies inside the Unity project, so I changed my references to use that path.
Unfortunately, Visual Studio's compiler still wasn't satisfied. One of the classes in UnityUtil is called ScrollRectVelocityClamper, and zeroes out ScrollRect.velocity for very low scroll velocities, as a performance optimization. Unfortunately, I got compiler errors on all lines accessing ScrollRect.velocity, with the following error:
Error CS0012 The type 'Vector2' is defined in an assembly that is not referenced. You must add a reference to assembly 'UnityEngine.CoreModule, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null'.
So apparently the new UnityEngine.UI.dll in 2019.2 (which declares ScrollRect.velocity) directly references UnityEngine.CoreModule.dll (which declares Vector2), rather than UnityEngine.dll. So I replaced the UnityEngine.dll reference in UnityUtil with references to the various module assemblies that I'm using (including core module).
But now, my UnityUtil.Editor assembly is unsatisfied. As I did above, I replaced the UnityEngine.dll reference in UnityUtil.Editor with references to the specific Unity modules that I'm using, including the core module. UnityUtil.Editor defines an Editor for a class in UnityUtil derived from ScriptableObject and is showing a similar error to that above:
Error CS0012 The type 'ScriptableObject' is defined in an assembly that is not referenced. You must add a reference to assembly 'UnityEngine, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null'.
This error doesn't make sense to me. Why does the compiler think that ScriptableObject is defined in UnityEngine.dll, if both UnityUtil and UnityUtil.Editor are referencing UnityEngine.CoreModule.dll, not UnityEngine.dll? I can't just make UnityUtil.Editor reference UnityEngine.dll also, because then there are duplicate declaration (CS0433) errors. Nor can UnityUtil.Editor reference UnityEngine.dll instead of the module assemblies, because then I get similar CS0012 errors to what I first saw in UnityUtil, about types like Sprite being "defined in an assembly that is not referenced", namely UnityEngine.CoreModule.dll.
Has anyone else run into these complex reference issues when making managed plugins for Unity 2019.2+? I could really use some guidance. Thanks in advance!
