Bug 35388 - Attached properties break XAML compilation
Summary: Attached properties break XAML compilation
Alias: None
Product: Forms
Classification: Xamarin
Component: Forms ()
Version: 1.5.1
Hardware: PC Mac OS
: --- normal
Target Milestone: ---
Assignee: Stephane Delcroix
Depends on:
Reported: 2015-10-29 21:33 UTC by Kent
Modified: 2015-11-05 19:53 UTC (History)
4 users (show)

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

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Description Kent 2015-10-29 21:33:52 UTC
If I define an attached property, such as:

    public static class ListViewBehavior
        public static BindableProperty IsSelectionEnabledProperty = BindableProperty.CreateAttached(
            propertyChanged: OnIsSelectionEnabledChanged);

        private static void OnIsSelectionEnabledChanged(BindableObject bindable, object oldValue, object newValue)
            var listView = (ListView)bindable;

            if ((bool)newValue)
                listView.ItemSelected -= OnListViewItemSelected;
                listView.ItemSelected += OnListViewItemSelected;

        private static void OnListViewItemSelected(object sender, SelectedItemChangedEventArgs e)
            ((ListView)sender).SelectedItem = null;

Then try to use it in compiled XAML as follows:

    <ListView b:ListViewBehavior.IsSelectionEnabled="false">

I get a compilation error:

    error : Position 17:47. No property, bindable property, or event found for 'IsSelectedEnabled'

The XAML works fine when compilation is disabled.
Comment 1 Stephane Delcroix 2015-11-02 05:36:01 UTC
Are you sure the pasted snippet of code represents your actual code ?

the error speaks about `IsSelectedEnabled` while your property is `IsSelectionEnabled`
Comment 2 Stephane Delcroix 2015-11-02 09:33:10 UTC
adding a 

public static bool Get IsSelectionEnabled (BindableObject view) {
    return (bool) view.GetValue(IsSelectionEnabledProperty);

should get you through
Comment 3 Kent 2015-11-05 19:29:52 UTC
Now I'm getting a completely different error even without having added the static accessors:

error MSB4018: The "XamlCTask" task failed unexpectedly.
System.ArgumentOutOfRangeException: Specified argument was out of the range of valid values.

Server stack trace: 
   at Mono.Collections.Generic.Collection`1.get_Item(Int32 index)
   at Xamarin.Forms.Build.Tasks.XamlCTask.Compile()
   at Xamarin.Forms.Build.Tasks.XamlCTask.Execute()
   at System.Runtime.Remoting.Messaging.StackBuilderSink._PrivateProcessMessage(IntPtr md, Object[] args, Object server, Object[]& outArgs)
   at System.Runtime.Remoting.Messaging.StackBuilderSink.SyncProcessMessage(IMessage msg)

Exception rethrown at [0]: 
   at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
   at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
   at Microsoft.Build.Framework.ITask.Execute()
   at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
   at Microsoft.Build.BackEnd.TaskBuilder.<ExecuteInstantiatedTask>d__26.MoveNext()

I think I'll email support and include my project at this point. I'll update this ticket again once I have a resolution.
Comment 4 Kent 2015-11-05 19:53:14 UTC
Hmm, it seems a complete clean (git clean -xdf) and rebuild has resolved the issue (in conjunction with the static accessors, as you suggested).