Bug 13356 - Invalid IL code when using .Wait () instead of await
Summary: Invalid IL code when using .Wait () instead of await
Alias: None
Product: Compilers
Classification: Mono
Component: C# ()
Version: unspecified
Hardware: Macintosh Mac OS
: --- normal
Target Milestone: ---
Assignee: Marek Safar
Depends on:
Reported: 2013-07-19 19:18 UTC by Timothy Risi
Modified: 2015-05-30 01:24 UTC (History)
4 users (show)

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

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Description Timothy Risi 2013-07-19 19:18:03 UTC
I'm working on adding async to the MonoCatalog-MonoDevelop sample (code attached).  There's one call that works correctly if I await it, but crashes with 'System.AggregateException:  ---> System.Exception: Invalid IL code in ...' if I instead use .Wait ().

Full stacktrace:

System.AggregateException:  ---> System.Exception: Invalid IL code in MonoCatalog.MonoDataSqliteController/ItemsDataSource/<GetKeyValuePairCell>c__async5/<GetKeyValuePairCell>c__AnonStorey10/<GetKeyValuePairCell>c__asyncF:MoveNext (): IL_00c2: stloc.2   
  at System.Runtime.CompilerServices.AsyncTaskMethodBuilder.Start[<GetKeyValuePairCell>c__asyncF] (MonoCatalog.<GetKeyValuePairCell>c__asyncF& stateMachine) [0x0001b] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Runtime.CompilerServices/AsyncTaskMethodBuilder.cs:112
  at MonoCatalog.MonoDataSqliteController+ItemsDataSource+<GetKeyValuePairCell>c__async5+<GetKeyValuePairCell>c__AnonStorey10.<>m__1C (Mono.Data.Sqlite.SqliteCommand c) [0x00010] in /Users/Tim/Projects/Xamarin/monotouch-samples/MonoCatalog-MonoDevelop/MonoDataSqlite.xib.cs:179
  at MonoCatalog.MonoDataSqliteController+<WithCommandAysnc>c__async3+<WithCommandAysnc>c__AnonStorey19+<WithCommandAysnc>c__async18.MoveNext () [0x00044] in /Users/Tim/Projects/Xamarin/monotouch-samples/MonoCatalog-MonoDevelop/MonoDataSqlite.xib.cs:282
  at --- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000b] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Runtime.ExceptionServices/ExceptionDispatchInfo.cs:62
  at System.Runtime.CompilerServices.TaskAwaiter.GetResult () [0x00043] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Runtime.CompilerServices/TaskAwaiter.cs:60
  at MonoCatalog.MonoDataSqliteController+<WithConnectionAsync>c__async2.MoveNext () [0x000e2] in /Users/Tim/Projects/Xamarin/monotouch-samples/MonoCatalog-MonoDevelop/MonoDataSqlite.xib.cs:271
  at --- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000b] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Runtime.ExceptionServices/ExceptionDispatchInfo.cs:62
  at System.Runtime.CompilerServices.TaskAwaiter.GetResult () [0x00043] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Runtime.CompilerServices/TaskAwaiter.cs:60
  at MonoCatalog.MonoDataSqliteController+<WithCommandAysnc>c__async3.MoveNext () [0x0003e] in /Users/Tim/Projects/Xamarin/monotouch-samples/MonoCatalog-MonoDevelop/MonoDataSqlite.xib.cs:280
  --- End of inner exception stack trace ---
  at System.Threading.Tasks.Task.Wait (Int32 millisecondsTimeout, CancellationToken cancellationToken) [0x00048] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/Task.cs:651
  at System.Threading.Tasks.Task.Wait () [0x00000] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Threading.Tasks/Task.cs:621
  at MonoCatalog.MonoDataSqliteController+ItemsDataSource+<GetKeyValuePairCell>c__async5.MoveNext () [0x0004e] in /Users/Tim/Projects/Xamarin/monotouch-samples/MonoCatalog-MonoDevelop/MonoDataSqlite.xib.cs:186
  at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1[MonoTouch.UIKit.UITableViewCell].Start[<GetKeyValuePairCell>c__async5] (MonoCatalog.<GetKeyValuePairCell>c__async5& stateMachine) [0x0001b] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Runtime.CompilerServices/AsyncTaskMethodBuilder_T.cs:112
  at MonoCatalog.MonoDataSqliteController+ItemsDataSource.GetKeyValuePairCell (MonoTouch.UIKit.UITableView tableView, MonoTouch.Foundation.NSIndexPath indexPath) [0x00000] in <filename unknown>:0
  at MonoCatalog.MonoDataSqliteController+ItemsDataSource.GetCell (MonoTouch.UIKit.UITableView tableView, MonoTouch.Foundation.NSIndexPath indexPath) [0x00015] in /Users/Tim/Projects/Xamarin/monotouch-samples/MonoCatalog-MonoDevelop/MonoDataSqlite.xib.cs:95
  at at (wrapper managed-to-native) MonoTouch.UIKit.UIApplication:UIApplicationMain (int,string[],intptr,intptr)
  at MonoTouch.UIKit.UIApplication.Main (System.String[] args, System.String principalClassName, System.String delegateClassName) [0x0004c] in /Developer/MonoTouch/Source/monotouch/src/UIKit/UIApplication.cs:38
  at MonoTouch.Application.Main (System.String[] args) [0x00004] in /Users/Tim/Projects/Xamarin/monotouch-samples/MonoCatalog-MonoDevelop/Main.cs:16

Expected Behavior: 

Method executes and parent method continues executing synchronously

Steps to reproduce:

1)  Run sample app
2)  Select the row "Mono.Data.Sqlite" - Exception occurs at like 186 in MonoDataSqlite.xib.cs

The problem occurs in the file MonoDataSqlite.xib.cs with the method call to WithCommandAsync starting at line 179.

WithCommandAysnc (async c => {
        c.CommandText = query;
        var r = await c.ExecuteReaderAsync ();
	while (await r.ReadAsync ()) {
	        key   = r ["Key"].ToString ();
	        value = r ["Value"].ToString ();
}).Wait ();

using 'await WithCommandAsync (...}' instead works correctly.

Running on OS X 10.8.4
Xamarin Studio
Version 4.0.10 (build 3)
Installation UUID: 163f9b0a-f1be-4283-ae88-7b65a18efe5b
	Mono 3.1.2 ((no/4cb023e)
	GTK 2.24.20
	GTK# (
	Package version: 301020000

Apple Developer Tools
Xcode 4.6.3 (2068)
Build 4H1503

Version: (Business Edition)
Hash: c9f7659
Build date: 2013-18-07 21:36:03-0400
Comment 1 Timothy Risi 2013-07-19 19:55:30 UTC
Internet died, will upload the example  when I get internet back
Comment 2 Timothy Risi 2013-07-20 19:46:35 UTC
Added test case url
Comment 3 Jakub Arnold 2013-10-13 12:46:09 UTC
I'm having the same issue when I mark one of my lambda callbacks with `async`.

            SearchForAddress(query, (async (IList<IAddressResult> results, Exception error) =>
                if (error != null)

If I remove the async modifier everything works fine, but I get the runtime "Invalid IL code" with the async modifier.
Comment 4 Dillon Buchananq 2013-10-13 15:17:37 UTC
Great... I get something similar too when I do some BS like:

var sheet = new UIActionSheet();
sheet.Clicked = async (s, e) => {
    if (someval)
      await SomeAwaitTask();
  catch (exception)

I think the compiler miscompiles this because not all conditional paths result in some sort of await. If I simply add a 'await Task.Delay(1)' after the 'SomeNonAwait' the problem goes away. Either way, this is redonkulous because this is not the first 'async/await' issue I've encountered with Xamarin.iOS since the 7.0 release. It makes me nervous to release an App with any async/await methods in it for fear that another goofy exception, like this one, will cause the app to crash along with the ratings.
Comment 5 Marek Safar 2015-05-30 01:24:26 UTC
This should be fixed in mono master