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Created attachment 2017 [details]
AppDelegate used to recreate the crash.
I have a sample here that fails with the following error when running on device. I realise that the compiler can't always figure out what to generate ahead of time with generics but thought that it might be a useful test case.
I created a new iPhone application and used the attached AppDelegate.cs. It doesn't have a window - it just crashes instead :) I have been experimenting with some Rx type functions and found this case which crashes on the device.
I have read in a few of the other bug reports that there might be more issues with value types in generics, is this true?
Unhandled Exception: System.ExecutionEngineException: Attempting to JIT compile method 'AotTest.ObservableExtensions:<Subscribe`1>m__8<AotTest.Unit> (AotTest.Unit)' while running with --aot-only.
at AotTest.AnonymousObserver`1[AotTest.Unit].OnNext (Unit value) [0x0000b] in /Users/sgm/Projects/Test/AotTestBackup/AotTest/AppDelegate.cs:358
at AotTest.MainThreadObservableExtensions+<ObserveOnMainThread>c__AnonStorey4`1+<ObserveOnMainThread>c__AnonStorey5`1[AotTest.Unit].<>m__D (Unit next) [0x00000] in /Users/sgm/Projects/Test/AotTestBackup/AotTest/AppDelegate.cs:419
at AotTest.MainThreadObserver`1+<OnNext>c__AnonStorey7[AotTest.Unit].<>m__12 () [0x00000] in /Users/sgm/Projects/Test/AotTestBackup/AotTest/AppDelegate.cs:484
at MonoTouch.Foundation.NSActionDispatcher.Apply () [0x00000] in /Developer/MonoTouch/Source/monotouch/src/shared/Foundation/NSAction.cs:48
at MonoTouch.UIKit.UIApplication.Main (System.String args, System.String principalClassName, System.String delegateClassName) [0x00042] in /Developer/MonoTouch/Source/monotouch/src/UIKit/UIApplication.cs:29
at AotTest.Application.Main (System.String args) [0x00000] in /Users/sgm/Projects/Test/AotTestBackup/AotTest/Main.cs:37
[ERROR] FATAL UNHANDLED EXCEPTION: System.ExecutionEngineException: Attempting to JIT compile method 'AotTest.ObservableExtensions:<Subscribe`1>m__8<AotTest.Unit> (AotTest.Unit)' while running with --aot-only.
Changing the 'Unit' type from a struct to a class does actually 'fix' the issue, which leads me to think that generics and value types can have more issues.
This still fails with 6.2.6 but works with 6.3.x.
The 6.3.x beta releases have much improved to avoid this situation (the EngineExecutionException). You might want to try this, or similar code, again and report any remaining issues (with a test case).