Bug 2729 - LINQ failing on device, but works in simulator.
Summary: LINQ failing on device, but works in simulator.
Alias: None
Product: iOS
Classification: Xamarin
Component: Xamarin.iOS.dll ()
Version: 4.x
Hardware: PC Mac OS
: Normal normal
Target Milestone: Untriaged
Assignee: Bugzilla
Depends on:
Reported: 2012-01-03 19:29 UTC by Dominique
Modified: 2013-06-02 12:51 UTC (History)
3 users (show)

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

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Description Dominique 2012-01-03 19:29:33 UTC
I'm loading an XML file on startup, using the following code...

var xdoc = XDocument.Load(filePath);

mapMarkers = (from c in xdoc.XPathSelectElements("./fixtures/fixture")		
	                let xName = (String)c.Attribute("name")
					let xAge = (int)c.Attribute("age") 
					orderby xAge
	                select new FixtureData() {                    
	                Name = xName,
			Age = xAge,

notice the "orderby xAge".

I then perform the following LINQ query

var ageGroups = ( from m in mapMarkers
							group m by m.Age into g
							orderby g.Key
							select new { Age = g.Key });
				foreach( var ag in ageGroups )
    // DO some funky stuff

On Devices, when the foreach statement is hit, the following exception is thrown...

"SystemExecutionEngineException has been thrown
Attempting to JIT compile method 'System.Linq.OrderedSequence'2<<>__AnonType9'2<<>__AnonType8'2.............) while running with --aot-only."

If you now remove the "orderby xAge" statement, everything works on both the device and in the simulator.
Comment 1 Sebastien Pouliot 2012-03-01 19:20:27 UTC
This is one of the generic limitations described in http://docs.xamarin.com/ios/about/limitations#Limited_Generics_Support

It's likely similar to other reported issues (e.g. bug #3114) but we need a complete test case to confirm this (many things vary depending on how things like FixtureData are defined).
Comment 2 Dominique 2012-03-01 19:45:49 UTC
HI Sebastien,
  I'm fairly sure I tried it without the FixtureData and instead using an anonymous type and it still complained.

I'll try and create a full test case for it tomorrow.

Thanks for taking a look at it.

Comment 3 Sebastien Pouliot 2013-06-02 12:51:27 UTC
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).