If AxisControl value is accessed twice in a callback there is an InvalidOperationException

[jackpr-unity]

Reproduction Steps: RiftAxisDoubleRead.zip

• Add the attached package to this repository
• Set up VR with the Oculus SDK
• Open the RiftActions scene, press play
• Attempt to pull the left trigger

Expected: The slider and the adjacent text updates to the correct value.

Observed: InvalidOperationException based on modifier phases

This was found with

• Unity Editor /xr/sdk/input-subsystem changeset 352080
• This repo changeset 41b5834

Notes:

• I can not reproduce this issue using the upstream project, so updating to that might just fix this.
• The issue is definitely in AxisControlActionStatus.UpdateAxis. If you remove the last line of code, it will not fail. The error seems to occur only when you try to use the axis control value more than once in the single callback, even if you first store the value into a local variable first. ReadValue returns a float in this case, but the definition of ReadValue is actually templated. I think the templated return value causes a return by reference, which causes the problem.

My Conjecture: AxisControl.ReadValue is somehow returning by reference to a function, and when the local variable is accessed more than once the control is trying to update its phase a second time.

Stack Trace: InvalidOperationException: Cannot go from 'Performed' to 'Performed'; must be 'Waiting' or 'Started' (action: Axis, modifier: ) UnityEngine.Experimental.Input.InputAction.ThrowIfPhaseTransitionIsInvalid (Phase currentPhase, Phase newPhase, Int32 bindingIndex, Int32 modifierIndex) (at Packages/com.unity.inputsystem/InputSystem/Actions/InputAction.cs:737) UnityEngine.Experimental.Input.InputAction.ChangePhaseOfAction (Phase newPhase, UnityEngine.Experimental.Input.TriggerState& trigger) (at Packages/com.unity.inputsystem/InputSystem/Actions/InputAction.cs:570) UnityEngine.Experimental.Input.InputAction.NotifyControlValueChanged (UnityEngine.Experimental.Input.InputControl control, Int32 bindingIndex, Double time) (at Packages/com.unity.inputsystem/InputSystem/Actions/InputAction.cs:835) UnityEngine.Experimental.Input.InputManager.FireActionStateChangeNotifications (Int32 deviceIndex, Double time) (at Packages/com.unity.inputsystem/InputSystem/InputManager.cs:1982) UnityEngine.Experimental.Input.InputManager.OnUpdate (InputUpdateType updateType, Int32 eventCount, IntPtr eventData) (at Packages/com.unity.inputsystem/InputSystem/InputManager.cs:1836) UnityEngine.Experimental.Input.LowLevel.NativeInputRuntime+<>cAnonStorey0.<>m0 (NativeInputUpdateType updateType, Int32 eventCount, IntPtr eventPtr) (at Packages/com.unity.inputsystem/InputSystem/NativeInputRuntime.cs:57) UnityEngineInternal.Input.NativeInputSystem.NotifyUpdate (NativeInputUpdateType updateType, Int32 eventCount, IntPtr eventData) (at C:/Users/jackpr/Ono/unity/Modules/Input/Private/Input.cs:90) UnityEditor.EditorGUIUtility:RenderGameViewCamerasInternal_Injected(RenderTexture, Int32, Rect&, Vector2&, Boolean) UnityEditor.EditorGUIUtility:RenderGameViewCamerasInternal(RenderTexture, Int32, Rect, Vector2, Boolean) UnityEditor.GameView:OnGUI() (at C:/Users/jackpr/Ono/unity/Editor/Mono/GameView/GameView.cs:799) System.Reflection.MonoMethod:InternalInvoke(Object, Object[], Exception&) System.Reflection.MonoMethod:Invoke(Object, BindingFlags, Binder, Object[], CultureInfo) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:222) System.Reflection.MethodBase:Invoke(Object, Object[]) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MethodBase.cs:115) UnityEditor.HostView:Invoke(String, Object) (at C:/Users/jackpr/Ono/unity/Editor/Mono/HostView.cs:295) UnityEditor.HostView:Invoke(String) (at C:/Users/jackpr/Ono/unity/Editor/Mono/HostView.cs:288) UnityEditor.HostView:InvokeOnGUI(Rect) (at C:/Users/jackpr/Ono/unity/Editor/Mono/HostView.cs:255) UnityEditor.DockArea:OldOnGUI() (at C:/Users/jackpr/Ono/unity/Editor/Mono/GUI/DockArea.cs:390) UnityEngine.Experimental.UIElements.IMGUIContainer:DoOnGUI(Event, Boolean) (at C:/Users/jackpr/Ono/unity/Modules/UIElements/IMGUIContainer.cs:218) UnityEngine.Experimental.UIElements.IMGUIContainer:HandleIMGUIEvent(Event) (at C:/Users/jackpr/Ono/unity/Modules/UIElements/IMGUIContainer.cs:383) UnityEngine.Experimental.UIElements.IMGUIContainer:DoRepaint(IStylePainter) (at C:/Users/jackpr/Ono/unity/Modules/UIElements/IMGUIContainer.cs:90) UnityEngine.Experimental.UIElements.Panel:PaintSubTree(Event, VisualElement, Matrix4x4, ClippingOptions, Rect) (at C:/Users/jackpr/Ono/unity/Modules/UIElements/Panel.cs:730) UnityEngine.Experimental.UIElements.Panel:PaintSubTreeChildren(Event, VisualElement, Matrix4x4, ClippingOptions, Rect) (at C:/Users/jackpr/Ono/unity/Modules/UIElements/Panel.cs:746) UnityEngine.Experimental.UIElements.Panel:PaintSubTree(Event, VisualElement, Matrix4x4, ClippingOptions, Rect) (at C:/Users/jackpr/Ono/unity/Modules/UIElements/Panel.cs:734) UnityEngine.Experimental.UIElements.Panel:Repaint(Event) (at C:/Users/jackpr/Ono/unity/Modules/UIElements/Panel.cs:776) UnityEngine.Experimental.UIElements.UIElementsUtility:DoDispatch(BaseVisualElementPanel) (at C:/Users/jackpr/Ono/unity/Modules/UIElements/UIElementsUtility.cs:230) UnityEngine.Experimental.UIElements.UIElementsUtility:ProcessEvent(Int32, IntPtr) (at C:/Users/jackpr/Ono/unity/Modules/UIElements/UIElementsUtility.cs:77) UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr) (at C:/Users/jackpr/Ono/unity/Modules/IMGUI/GUIUtility.cs:171)

[jackpr-unity]

updated title to communicate that this does not seem to be platform specific.