Type binding Error with .NET 9 Preview 6

[davidortinau]

Description

Testing .NET Hot Reload and .NET 9 Preview 6 I'm getting these errors:

Exception has occurred: CLR/System.TypeLoadException
An unhandled exception of type 'System.TypeLoadException' occurred in Mono.Android.Runtime.dll: 'Could not resolve type with token 01000075 from typeref (expected class 'Microsoft.Maui.Controls.Generated.<GeneratedBindableObjectExtensions_g>F340249EF3F4705EB00F29166AE5B0DC4FEF24016399EDCA95F8D25AC35F9B242__GeneratedBindableObjectExtensions' in assembly '')'
   at Android.Runtime.RuntimeNativeMethods.monodroid_debugger_unhandled_exception(Exception e)
   at Android.Runtime.JNINativeWrapper._unhandled_exception(Exception e)
   at Android.Runtime.JNINativeWrapper.Wrap_JniMarshal_PP_V(_JniMarshal_PP_V callback, IntPtr jnienv, IntPtr klazz)
   at SharpNine.FirstPage.Build() in /Users/davidortinau/work/SharpNine/FirstPage.cs:line 41
   at SharpNine.FirstPage.<.ctor>b__2_1()
   at Java.Lang.Thread.RunnableImplementor.Run()
   at Java.Lang.IRunnableInvoker.n_Run(IntPtr jnienv, IntPtr native__this)
   at Android.Runtime.JNINativeWrapper.Wrap_JniMarshal_PP_V(_JniMarshal_PP_V callback, IntPtr jnienv, IntPtr klazz)

Exception has occurred: CLR/System.TypeLoadException
An unhandled exception of type 'System.TypeLoadException' occurred in Microsoft.iOS.dll: 'Could not resolve type with token 01000072 from typeref (expected class 'Microsoft.Maui.Controls.Generated.<GeneratedBindableObjectExtensions_g>F340249EF3F4705EB00F29166AE5B0DC4FEF24016399EDCA95F8D25AC35F9B242__GeneratedBindableObjectExtensions' in assembly '')'
   at ObjCRuntime.Runtime.ThrowException(IntPtr gchandle)
   at UIKit.UIApplication.UIApplicationMain(Int32 argc, String[] argv, IntPtr principalClassName, IntPtr delegateClassName)
   at UIKit.UIApplication.Main(String[] args, Type principalClass, Type delegateClass)
   at SharpNine.Program.Main(String[] args) in /Users/davidortinau/work/SharpNine/Platforms/iOS/Program.cs:line 14

From changing anything in this method:

void Build()
	{
		Content = new VerticalStackLayout
		{
			Spacing = 20,
			Margin = 20,
			Children = {
				(label = new Label {  
					Text = "Welcome to .NET MAUI!",
					FontSize = 64,
					TextColor = Colors.Blue
				}),
				(entry = new Entry { Placeholder = "Enter your name" }),
			}
		};

		label.SetBinding(Label.TextProperty, static (Entry e) => e.Text, source: entry);
	}

The binding functions as I expect. @simonrozsival I suspect this is related to the compiled bindings work.

Commenting out the binding allows .NET Hot Reload to succeed without error. Returning to a non-compiled binding works as well:

label.SetBinding(Label.TextProperty, new Binding("Text", source: entry));

SharpNine.zip

Steps to Reproduce

No response

Link to public reproduction project repository

No response

Version with bug

9.0.0-preview.6.24327.7

Is this a regression from previous behavior?

No, this is something new

Last version that worked well

Unknown/Other

Affected platforms

iOS, Android, macOS

Affected platform versions

No response

Did you find any workaround?

No response

Relevant log output

No response

[github-actions]

Hi I'm an AI powered bot that finds similar issues based off the issue title.

Please view the issues below to see if they solve your problem, and if the issue describes your problem please consider closing this one and thumbs upping the other issue to help us prioritize it. Thank you!

Open similar issues:

• [.NET 9.0 Preview 5] Build error when SkiaSharp.Views.Maui.Controls.Compatibility is added to a project (#23108), similarity score: 0.75
• XamlC error XFC0045 with maui dotnet 9 preview 3 (#22318), similarity score: 0.74

Closed similar issues:

• [regression/8.0.0-preview.7.8842] System.TypeLoadException with .NET 8 (#17136), similarity score: 0.74
• XAMLC error in .NET 9 Preview 5 (#22975), similarity score: 0.74
• Weird behavior with Compiled Bindings (#13764), similarity score: 0.73

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[simonrozsival]

/cc @jkurdek

[Zhanglirong-Winnie]

This issue has been verified Visual Studio 17.11.0 Preview 3.0(9.0.0-preview.6.24327.7)& VSM 17.6.12(net9),Can repro on all platforms.

[simonrozsival]

I wonder if we can do something about this on our end or if this is some limitation of source generators and hot reload. It seems to me that the type name of the source generated class changes with every roslyn compilation:

In one instance, the type name before the update (obtained by listing types in the assembly via reflection) was:

Microsoft.Maui.Controls.Generated.<GeneratedBindableObjectExtensions_g>F8EAA02179AB123506AE8CCA05556D5DDF2EA0B3D7CB088DAB38382B52A1722F6__GeneratedBindableObjectExtensions

And the exception message compained about not being able to find this type:

Microsoft.Maui.Controls.Generated.<GeneratedBindableObjectExtensions_g>F66D27BD33A914CF7D49F79ED8311EF0A6D6053E8F683ECBDAD481FAF1B9ED440__GeneratedBindableObjectExtensions

The UpdateApplicationEvent delegate was called with two types (obj) and none of them was the <GeneratedBindableObjectExtensions_g>XYZ_GeneratedBindableObjectExtensions.

I'm not sure who on the Roslyn team or on the tooling team could help us diagnose this.

[simonrozsival]

The mangled names were caused by the class being file scoped. We changed it to internal in #23116 so this should be resolved in P7.