Please help me with this one, I've been writing a console applicaiton using the AsyncCtpLibrary and the C#5 ctp compiler. First time I got to actually running a code which awaits, I got this:
System.BadImageFormatException was unhandled
Message=An attempt was made to load a program with an incorrect format. (Exception from HRESULT: 0x8007000B)
Source=AsyncCtpLibrary
StackTrace:
Server stack trace:
at [...].<Execute>d__1c.MoveNext()
at [...].Execute()
at [...].<Move>d__1d.MoveNext() in[..]:line 266
Exception rethrown at [0]:
at System.Runtime.CompilerServices.AsyncVoidMethodBuilder.<SetException>b__1(Object state)
at System.Threading.QueueUserWorkItemCallback.WaitCallback_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
at System.Threading.ThreadPoolWorkQueue.Dispatch()
at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback()
InnerException:
Am I missing a dll to be referenced?
important new stuff
My failing method looks like this:
public async override Task<bool> Execute()
{
//do stuff
await stuff;
//do other stuff
await base.Execute()
//do other stuff
return true;
}
I've followed Jon Skeet's advice trying to recreate the mistake little by little, and now I can tell that the await base.Execute() line is the killer! If I comment that line out, everything runs, if I leave it in, calling my method fails IMMEDIATELY (not when reaching the base.Execute()). So I assume the ctp compiler does something freaky. Why? What should I never do? How big is the bug?
old stuff:
EDIT:
As for 32bit/64bit issue, my system is 32bit (inside a virtual machine, mind you), and as far as I know AsyncCtpLibrary.dll doesn't contain unmanaged code. All my projects (class libraries and single console app) all have build tabs like this:
What can possibly be still wrong?
EDIT: I also checked the Fusion log viewer, the AsyncCtpLibrary is loaded without any error:
*** Assembly Binder Log Entry (6/10/2011 @ 9:04:11 PM) ***
The operation was successful.
Bind result: hr = 0x0. The operation completed successfully.
Assembly manager loaded from: C:\Windows\Microsoft.NET\Framework\v4.0.30319\clr.dll
Running under executable C:\Users\Daver\Documents\Visual Studio 2010\Projects\[...]\bin\Debug\MyApp.exe
--- A detailed error log follows.
=== Pre-bind state information ===
LOG: User = WIN-N74LV38NLV3\Daver
LOG: DisplayName = AsyncCtpLibrary, Version=1.0.4107.18181, Culture=neutral, PublicKeyToken=31bf3856ad364e35
(Fully-specified)
LOG: Appbase = file:///C:/Users/Daver/Documents/Visual Studio 2010/Projects/[...]/bin/Debug/
LOG: Initial PrivatePath = NULL
LOG: Dynamic Base = NULL
LOG: Cache Base = NULL
LOG: AppName = MyApp.exe
Calling assembly : MyLibrary, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null.
===
LOG: This bind starts in default load context.
LOG: Using application configuration file: C:\Users\Daver\Documents\Visual Studio 2010\Projects\[...]\bin\Debug\MyApp.exe.Config
LOG: Using host configuration file:
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v4.0.30319\config\machine.config.
LOG: Post-policy reference: AsyncCtpLibrary, Version=1.0.4107.18181, Culture=neutral, PublicKeyToken=31bf3856ad364e35
LOG: GAC Lookup was unsuccessful.
LOG: Attempting download of new URL file:///C:/Users/Daver/Documents/Visual Studio 2010/Projects/[...]/bin/Debug/AsyncCtpLibrary.DLL.
LOG: Assembly download was successful. Attempting setup of file: C:\Users\Daver\Documents\Visual Studio 2010\Projects\[...]\bin\Debug\AsyncCtpLibrary.dll
LOG: Entering run-from-source setup phase.
LOG: Assembly Name is: AsyncCtpLibrary, Version=1.0.4107.18181, Culture=neutral, PublicKeyToken=31bf3856ad364e35
LOG: Binding succeeds. Returns assembly from C:\Users\Daver\Documents\Visual Studio 2010\Projects\[...]\bin\Debug\AsyncCtpLibrary.dll.
LOG: Assembly is loaded in default load context.
I also checked the IL code of the <Execute>d__1c
compiler-generated class' MoveNext() method, and the only assemblies it references ([assemblyName]) are mscorlib, System.Core, and AsyncCtpLibrary.
I checked the manifest of both my dll and AsyncCtpLibrary, mine said .corflags 0x00000003 // ILONLY 32BITREQUIRED
, AsyncCtpLibrary said .corflags 0x00000009 // ILONLY
, I'm unsure if this can be the problem.
Please help, I'm out of ideas!
EDIT: I've heard back from the compiler team, who have confirmed it as a bug. It had already been fixed in their codebase, so hopefully we'll see that fix in the next release / beta / CTP. The fix isn't going to be back-ported to "normal" VS2010 as it's a pretty unusual set of circumstances, at least before async.
EDIT: Okay, I've now got a really short but complete program which demonstrates the problem. I believe it's a mixture of generics and calling a base method:
using System;
using System.Threading.Tasks;
public abstract class AsyncAction<T>
{
public virtual Task<T> Execute()
{
// We never get this far
Console.WriteLine("Execute called");
return null;
}
}
public class BoolAction : AsyncAction<bool>
{
public async override Task<bool> Execute()
{
return await base.Execute();
}
}
class Test
{
static void Main()
{
BoolAction b = new BoolAction();
b.Execute();
}
}
EDIT: Okay, I've come up with a workaround. Basically, to call the base class method non-virtually, the compiler creates a synthetic method in BoolAction
. It gets that slightly wrong, but we can get it right:
public class BoolAction : AsyncAction<bool>
{
public async override Task<bool> Execute()
{
return await BaseExecute();
}
private Task<bool> BaseExecute()
{
return base.Execute();
}
}
So whenever you were writing base.Execute
, write BaseExecute
and insert that extra method. It's not too bad a workaround, until the team fix the bug.
EDIT: I've simplified the example a bit - you don't need any overrides, and in particular you don't need the base class to expose a Task<T>
. A call to any virtual base.Foo
method will do it:
public abstract class AsyncAction<T>
{
public virtual T GetT()
{
return default(T);
}
}
public class BoolAction : AsyncAction<bool>
{
#pragma warning disable 1998 // We're not awaiting anything
public async void Execute()
{
base.GetT();
}
#pragma warning restore 1998
}
class Test
{
static void Main()
{
BoolAction b = new BoolAction();
b.Execute();
}
}
EDIT: Contrary to my previous thoughts, this does affect iterators as well. No async CTP required...
public abstract class Base<T>
{
public virtual T GetT()
{
return default(T);
}
}
public class Derived : Base<bool>
{
public System.Collections.IEnumerator Foo()
{
base.GetT();
yield break;
}
}
class Test
{
static void Main()
{
Derived d = new Derived();
d.Foo().MoveNext();
}
}
EDIT: And it affects anonymous functions too...
using System;
public abstract class Base<T>
{
public virtual T GetT()
{
return default(T);
}
}
public class Derived : Base<bool>
{
public void Foo()
{
Action x = () => base.GetT();
x();
}
}
class Test
{
static void Main()
{
Derived d = new Derived();
d.Foo();
}
}
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