When reimporting assets or reloading the domain, Unity shows the following warning:
Assembly for Assembly Definition File 'Assets/Plugins/Sirenix/Odin Inspector/Scripts/Sirenix.OdinInspector.CompatibilityLayer.asmdef' will not be compiled, because it has no scripts associated with it. UnityEditor.Scripting.ScriptCompilation.EditorCompilationInterface:TickCompilationPipeline(EditorScriptCompilationOptions, BuildTargetGroup, BuildTarget, String)
Clearly, the mentioned
Sirenix.OdinInspector.CompatibilityLayer assembly definition has no scripts associated with it. Removing that asmdef file would stop this warning and spare us some noise in the Unity console.
Tested with Odin 188.8.131.52 in Edit Only mode on Unity 2020.1.8f1 on Windows 10.