Bug 34926 - AOT issue with await Task<bool> on Visual Studio 2015
Summary: AOT issue with await Task<bool> on Visual Studio 2015
Alias: None
Product: iOS
Classification: Xamarin
Component: Mono runtime / AOT compiler ()
Version: XI 9.2
Hardware: PC Windows
: High blocker
Target Milestone: 9.2 (C6)
Assignee: Zoltan Varga
Depends on:
Reported: 2015-10-15 22:50 UTC by Mark Smith
Modified: 2015-10-26 10:09 UTC (History)
14 users (show)

Tags: VSXF
Is this bug a regression?: ---
Last known good build:

Sample Project + Screenshot (1.46 MB, application/zip)
2015-10-15 22:50 UTC, Mark Smith

Notice (2018-05-24): bugzilla.xamarin.com is now in read-only mode.

Please join us on Visual Studio Developer Community and in the Xamarin and Mono organizations on GitHub to continue tracking issues. Bugzilla will remain available for reference in read-only mode. We will continue to work on open Bugzilla bugs, copy them to the new locations as needed for follow-up, and add the new items under Related Links.

Our sincere thanks to everyone who has contributed on this bug tracker over the years. Thanks also for your understanding as we make these adjustments and improvements for the future.

Please create a new report on Developer Community or GitHub with your current version information, steps to reproduce, and relevant error messages or log files if you are hitting an issue that looks similar to this resolved bug and you do not yet see a matching new report.

Related Links:

Description Mark Smith 2015-10-15 22:50:35 UTC
Created attachment 13359 [details]
Sample Project + Screenshot

Calling a method that returns Task<bool> and attempting to await on it generates an exception on physical device:

System.ExecutionEngineException: Attempting to JIT compile method 'System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1<bool>:System.Runtime.CompilerServices.IAsyncMethodBuilder.PreBoxInitialization<TStateMachine> (TStateMachine&)' while running with --aot-only. See http://docs.xamarin.com/ios/about/limitations for more information.

(See attached screenshot).

However, if you take the same project and build it under Xamarin Studio on the Mac, it runs fine on the same device.

Sample Project attached.

=== Xamarin Studio ===

Version 5.10 (build 811)
Installation UUID: 50562e10-5ff9-448f-b0e4-17ca662d9b75
	Mono 4.2.1 (explicit/804ddbc)
	GTK+ 2.24.23 (Raleigh theme)

	Package version: 402010060

=== Xamarin.Profiler ===

Location: /Applications/Xamarin Profiler.app/Contents/MacOS/Xamarin Profiler

=== Xamarin.Android ===

Version: (Business Edition)
Android SDK: /Users/mark/Android/sdk
	Supported Android versions:
		2.3    (API level 10)
		4.0.3  (API level 15)
		4.1    (API level 16)
		4.2    (API level 17)
		4.3    (API level 18)
		4.4    (API level 19)
		4.4.87 (API level 20)
		5.0    (API level 21)
		5.1    (API level 22)
		6.0    (API level 23)

SDK Tools Version: 24.3.4
SDK Platform Tools Version: 23
SDK Build Tools Version: 23

Java SDK: /usr
java version "1.7.0_75"
Java(TM) SE Runtime Environment (build 1.7.0_75-b13)
Java HotSpot(TM) 64-Bit Server VM (build 24.75-b04, mixed mode)

=== Xamarin Android Player ===

Version: 0.6.2
Location: /Applications/Xamarin Android Player.app

=== Apple Developer Tools ===

Xcode 7.0.1 (8228)
Build 7A1001

=== Xamarin.Mac ===

Version: (Business Edition)

=== Xamarin.iOS ===

Version: (Business Edition)
Hash: b5396c2
Branch: master
Build date: 2015-09-30 15:22:15-0400

=== Build Information ===

Release ID: 510000811
Git revision: 34cd31ea72536afab530c14d9220b286075e83cd
Build date: 2015-09-30 10:40:37-04
Xamarin addins: 8e6fccfc0c19a7e0b7b11be925f09751d827eb5c
Build lane: monodevelop-lion-cycle6

=== Operating System ===

Mac OS X 10.11.1
Darwin Marks-MBP-2.local 15.0.0 Darwin Kernel Version 15.0.0
    Sun Oct 11 19:48:54 PDT 2015
    root:xnu-3247.10.11~3/RELEASE_X86_64 x86_64

Microsoft Visual Studio Enterprise 2015
Version 14.0.23107.0 D14REL
Microsoft .NET Framework
Version 4.6.00079

Installed Version: Enterprise

Architecture and Modeling Tools   00322-90150-03764-AA760
Microsoft Architecture and Modeling Tools
UML® and Unified Modeling Language™ are trademarks or registered trademarks of the Object Management Group, Inc. in the United States and other countries.

Visual Basic 2015   00322-90150-03764-AA760
Microsoft Visual Basic 2015

Visual C# 2015   00322-90150-03764-AA760
Microsoft Visual C# 2015

Visual C++ 2015   00322-90150-03764-AA760
Microsoft Visual C++ 2015

Windows Phone SDK 8.0 - ENU   00322-90150-03764-AA760
Windows Phone SDK 8.0 - ENU

Application Insights Tools for Visual Studio Package   1.0
Application Insights Tools for Visual Studio

ASP.NET and Web Tools   14.0.20626.0
ASP.NET and Web Tools

ASP.NET Web Frameworks and Tools 2013   5.2.30624.0
For additional information, visit http://www.asp.net/

Color Theme Designer   1.0
Designer for creating new color themes

Common Azure Tools   1.5
Provides common services for use by Azure Mobile Services and Microsoft Azure Tools.

GenerateUnitTest   1.0
Generates unit test code for methods in classes under test.

GitHub.VisualStudio   1.0
A Visual Studio Extension that brings the GitHub Flow into Visual Studio.

JetBrains ReSharper Ultimate 2015.2   Build 103.0.20150818.200216
JetBrains ReSharper Ultimate package for Microsoft Visual Studio. For more information about ReSharper Ultimate, visit http://www.jetbrains.com/resharper. Copyright © 2015 JetBrains, Inc.

Microsoft Azure Mobile Services Tools   1.4
Microsoft Azure Mobile Services Tools

Microsoft Code Digger   0.9
Microsoft Code Digger

Microsoft.Pex.VisualStudio   1.0

NuGet Package Manager   3.2.0
NuGet Package Manager in Visual Studio. For more information about NuGet, visit http://docs.nuget.org/.

PreEmptive Analytics Visualizer   1.2
Microsoft Visual Studio extension to visualize aggregated summaries from the PreEmptive Analytics product.

SQL Server Data Tools   14.0.50717.0
Microsoft SQL Server Data Tools

Visual Studio Spell Checker   VSSpellChecker
An editor extension that checks the spelling of comments, strings, and plain text as you type.

Visual Studio Tools for Universal Windows Apps   14.0.23121.00 D14OOB
The Visual Studio Tools for Universal Windows apps allow you to build a single universal app experience that can reach every device running Windows 10: phone, tablet, PC, and more. It includes the Microsoft Windows 10 Software Development Kit.

Web Essentials 2015   0.5.183
Adds many useful features to Visual Studio for web developers.

Xamarin (5abb0de)
Visual Studio extension to enable development for Xamarin.iOS and Xamarin.Android.

Xamarin.Android (f94dc5b)
Visual Studio plugin to enable development for Xamarin.Android.

Xamarin.iOS (b5396c2)
Visual Studio extension to enable development for Xamarin.iOS.
Comment 1 PJ 2015-10-15 23:02:10 UTC
Since this manifests only when building from VS, moving there.
Comment 2 Zoltan Varga 2015-10-16 00:22:57 UTC
This usually happens when the -O=gsharedvt argument is not passed to the aot compiler. Could you attach the build output ?
Comment 3 Arpit Jha 2015-10-16 08:41:38 UTC
I have checked this issue and able to reproduce this issue using build
monotouch- and steps mentioned in bug description.

Screencast: http://www.screencast.com/t/pu5uMz1ZvEO
Exception: https://gist.github.com/Rajneesh360Logica/d5bf7de17ba8c49db4e9
VS IDE log: https://gist.github.com/Rajneesh360Logica/6ffea89c289196e9aa77

Observation: VS throws exception when launching application on physical device.

REGRESSION: This issue is working fine with latest stable

Environment Info:
Device:iPhone 4s (iOS 9.0)
Windows: https://gist.github.com/Rajneesh360Logica/8f734c7126ea55c91ca3
Mac:    https://gist.github.com/Arpit360/438405f2b46da57a282f
Comment 4 Arpit Jha 2015-10-16 09:29:09 UTC
An update to comment 3 :
VS  Debug output : https://gist.github.com/Rajneesh360Logica/65c2496d6ad834c416c3
Comment 5 Arpit Jha 2015-10-16 09:50:24 UTC
An update to comment 3: 
Build output : https://gist.github.com/Rajneesh360Logica/9a0517ade979718e5d8f
Comment 6 Mark Smith 2015-10-16 11:19:17 UTC
@Zoltan --

I have verified that the "Share Generic Value Types" flag is checked in the VS project settings. I don't see any mtouch arguments for building in the IDE logs, would that be on the server side? If so, how can I retrieve those?
Comment 7 Mark Smith 2015-10-16 11:20:30 UTC
As an additional data point, if you change the return type to be a simple Task instead of Task<bool>, it works. It also works if you remove the async/await dependency and use ContinueWith constructs (where the state machine is not created).
Comment 8 Zoltan Varga 2015-10-16 12:18:52 UTC
Can you attach the mac side build log, its probably in some log file written to by the mac agent.
Comment 9 Mark Smith 2015-10-16 13:04:56 UTC
It does look like it's in the build output:
2>  Task Parameter:EnableGenericValueTypeSharing=True (TaskId:185)

Here's the full output:
Comment 12 Zoltan Varga 2015-10-18 16:22:50 UTC
Could you run the app with the MONO_LOG_LEVEL environment variable set to 'debug' and attach the output ? In xs, it can be set in Project Options/Run/General, no idea where to set them in VS.
Also, could you zip up the whole build directory on the build host (no idea where it is) and upload it somewhere ?
Comment 13 Arpit Jha 2015-10-19 05:46:16 UTC
I have checked this issue  with latest Cycle 6 build 

Observation: Getting Exception 

System.ExecutionEngineException: Attempting to JIT compile method 'System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1<bool>:System.Runtime.CompilerServices.IAsyncMethodBuilder.PreBoxInitialization<TStateMachine> (TStateMachine&)' while running with --aot-only. See http://docs.xamarin.com/ios/about/limitations for more information.

while app launches on physical device.

As per comment I have googled  https://bugzilla.xamarin.com/show_bug.cgi?id=34926#c12 MONO_LOG_LEVEL but observed that it works for android 

I have set MSBuild output to Diagnostic from Tools ->Option->Project and Solution ->Build and Run ->MSBUild Project build output to verbosity.

Build output: https://gist.githubusercontent.com/Rajneesh360Logica/0973da90d126bba6f36f/raw/d29d9a1de05de2126737d0dcd0b5efde659db0b3/gistfile1.txt 

iOS Device Crash Log: https://gist.github.com/Arpit360/896726fd5998f7beae0a

Please let me know if I can provide more info.

Environment Info:
Device : iPhone 4s (iOS 9.0)
Mac: https://gist.github.com/Arpit360/6cc858733a7082596ca4
Comment 15 Daniel Cazzulino 2015-10-19 11:12:25 UTC
Zoltan, is there anything more Arpit can provide?
Comment 16 Zoltan Varga 2015-10-19 17:50:47 UTC
I can't reproduce this. I was using this package:


and vs 2013 professional, plus x.ios on the mac.

Will try with vs2015.
Comment 17 Zoltan Varga 2015-10-19 22:59:37 UTC
This was an AOT compiler problem, it should be fixed by mono master 99d732d4d508feabdf95d737850490a427fb89b6.
Comment 18 Rolf Bjarne Kvinge [MSFT] 2015-10-20 06:13:53 UTC
@Sebastien, this looks like something we should get into C6SR1.
Comment 19 Miguel de Icaza [MSFT] 2015-10-20 09:51:43 UTC
Since this would be a regression against C5, this should likely go into C6-baseline.
Comment 20 Miguel de Icaza [MSFT] 2015-10-20 09:57:21 UTC
Zoltan, this applies fine to 4.2.0-branch, so I assume that this fix is what would fix our Cycle 6 as well, right?
Comment 21 Sebastien Pouliot 2015-10-20 10:19:53 UTC
Backport request tracked in https://trello.com/c/GAuMo9G6/304-xvs-34926-aot-issue-with-await-task-bool-on-visual-studio-2015

QA: This can be verified with maccore/master aa23e77f7fe09eeabfdc573d0b9cb41afb12f370
Comment 22 Miguel de Icaza [MSFT] 2015-10-20 11:07:22 UTC
In addition to the master, a build against cycle6/4.2 was created here, it is waiting to be built:

Comment 23 Zoltan Varga 2015-10-20 13:54:12 UTC
This is not really a regression, vs 2015 seems to generate different il, which exposed the problem in the generic sharing code.
Comment 24 Arpit Jha 2015-10-21 07:11:28 UTC
I have checked this issue with iOS http://storage.bos.internalx.com/macios-mac-master/aa/aa23e77f7fe09eeabfdc573d0b9cb41afb12f370/monotouch-
 and observed that issue is mentioned in bug description working fine.

App launched successfully on device.

After launching the app  Getting an exception of “System.Exception: Got an error from the web service.  MSG:success” while tapped on Testing.

Observation : As per my understanding this is the issue from service returning null data

I have reported the bug for the same https://bugzilla.xamarin.com/show_bug.cgi?id=35130

Screencast: http://www.screencast.com/t/fkgfwTZM

VS Environment Info: 

As per bug target milestone is C6, I will verify this issue once the patch will merge in C6
Comment 25 Miguel de Icaza [MSFT] 2015-10-21 09:32:30 UTC
Thanks for the feedback, so not a regression attributed to us, but our users will experience broken code when they move to VS 2015.
Comment 26 Udham Singh 2015-10-26 10:09:44 UTC
I have checked this issue with latest Cycle 6 lane builds and observed that the fix for this issue has been merged with Cycle 6 lane builds. Hence I am closing this issue.

Environment Info (Mac): https://gist.github.com/Udham1/afb7be7e414fea4aa44f
Environment Info (Windows): https://gist.github.com/Udham1/d1b0e8981b2da9e5c247