XamlParseException when using an Int32 value for a RadioButton

Description

I’m trying to bind some RadioButton views using System.Int32 values and separate display labels. I’m using <RadioButton.Value> in the XAML with the appropriate values.

On Android and Windows, this works fine. On iOS, it crashes with a XamlParseException.

Steps to Reproduce

1. Create a new MAUI app
2. Edit MainPage.xaml:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:sys="clr-namespace:System;assembly=mscorlib"
             x:Class="ReproInt32Combo.MainPage">

    <ScrollView>
        <VerticalStackLayout>
            <RadioButton Content="First">
                <RadioButton.Value>
                    <sys:Int32>1</sys:Int32>
                </RadioButton.Value>
            </RadioButton>
            <RadioButton Content="Second">
                <RadioButton.Value>
                    <sys:Int32>2</sys:Int32>
                </RadioButton.Value>
            </RadioButton>
        </VerticalStackLayout>
    </ScrollView>

</ContentPage>

1. Delete the C# code in MainPage.xaml.cs (except for the constructor)
2. Run on Windows or Android - no issues
3. Run on iOS and observe the exception below
4. Try x:Int32 instead of sys:Int32 and observe the same behavior

Exception:

System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation.
 ---> Microsoft.Maui.Controls.Xaml.XamlParseException: Position 11:22. Type sys:Int32 not found in xmlns clr-namespace:System;assembly=mscorlib
   at Microsoft.Maui.Controls.Xaml.CreateValuesVisitor.Visit(ElementNode node, INode parentNode)
   at Microsoft.Maui.Controls.Xaml.ElementNode.Accept(IXamlNodeVisitor visitor, INode parentNode)
   at Microsoft.Maui.Controls.Xaml.ElementNode.Accept(IXamlNodeVisitor visitor, INode parentNode)
   at Microsoft.Maui.Controls.Xaml.ElementNode.Accept(IXamlNodeVisitor visitor, INode parentNode)
   at Microsoft.Maui.Controls.Xaml.ElementNode.Accept(IXamlNodeVisitor visitor, INode parentNode)
   at Microsoft.Maui.Controls.Xaml.RootNode.Accept(IXamlNodeVisitor visitor, INode parentNode)
   at Microsoft.Maui.Controls.Xaml.XamlLoader.Visit(RootNode rootnode, HydrationContext visitorContext, Boolean useDesignProperties)
   at Microsoft.Maui.Controls.Xaml.XamlLoader.Load(Object view, String xaml, Assembly rootAssembly, Boolean useDesignProperties)
   at Microsoft.Maui.Controls.Xaml.XamlLoader.Load(Object view, String xaml, Boolean useDesignProperties)
   at Microsoft.Maui.Controls.Xaml.XamlLoader.Load(Object view, Type callingType)
   at Microsoft.Maui.Controls.Xaml.Extensions.LoadFromXaml[MainPage](MainPage view, Type callingType)
   at ReproInt32Combo.MainPage.InitializeComponent() in C:\Users\jon\Issues\AtYourService\MauiIpad\ReproInt32Combo\Microsoft.Maui.Controls.SourceGen\Microsoft.Maui.Controls.SourceGen.CodeBehindGenerator\MainPage.xaml.sg.cs:line 22
   at ReproInt32Combo.MainPage..ctor() in C:\Users\jon\Issues\AtYourService\MauiIpad\ReproInt32Combo\MainPage.xaml.cs:line 7
   at System.Reflection.RuntimeConstructorInfo.InternalInvoke(Object , Object[] , Boolean )
   --- End of inner exception stack trace ---
   at System.Reflection.RuntimeConstructorInfo.InternalInvoke(Object , Object[] , Boolean )
   at System.RuntimeType.CreateInstanceMono(Boolean , Boolean )
   at System.RuntimeType.CreateInstanceDefaultCtor(Boolean , Boolean )
   at System.Activator.CreateInstance(Type , Boolean , Boolean )
   at System.Activator.CreateInstance(Type , Boolean )
   at System.Activator.CreateInstance(Type )
   at Microsoft.Maui.Controls.ShellContent.<>c__DisplayClass19_0.<Microsoft.Maui.Controls.IShellContentController.GetOrCreateContent>b__0()
   at Microsoft.Maui.Controls.ElementTemplate.CreateContent()
   at Microsoft.Maui.Controls.Internals.DataTemplateExtensions.CreateContent(DataTemplate self, Object item, BindableObject container)
   at Microsoft.Maui.Controls.ShellContent.Microsoft.Maui.Controls.IShellContentController.GetOrCreateContent()
   at Microsoft.Maui.Controls.Platform.Compatibility.ShellSectionRootRenderer.LoadRenderers()
   at Microsoft.Maui.Controls.Platform.Compatibility.ShellSectionRootRenderer.ViewDidLoad()
   at UIKit.UIApplication.Main(String[] , Type , Type )
   at ReproInt32Combo.Program.Main(String[] args) in [...]

With x:Int32, the exception contains ---> Microsoft.Maui.Controls.Xaml.XamlParseException: Position 11:22. Type x:Int32 not found in xmlns http://schemas.microsoft.com/winfx/2009/xaml instead.

I’ve tried with the linker disabled, but the debugger didn’t even start then. (That could be an environmental issue.) I wouldn’t expect System.Int32 to be stripped anyway though… it’s a pretty fundamental type!

Version with bug

6.0.486 (current)

Last version that worked well

Unknown/Other

Affected platforms

iOS

Affected platform versions

iOS 15.6

Did you find any workaround?

No.

Relevant log output

No response

[jskeet]

@StephaneDelcroix: I’m afraid I can’t easily check at the moment. But I suspect given my earlier comment of “Bizarrely, I’ve just run this not in the debugger, and in Release mode, and it doesn’t crash” that it was then working in the simulator. Basically I think it’s “debug=boom, release=fine” regardless of simulator vs device.

[Greg-Bates-Trimble]

We have the same issue, but with a custom control. Means that our iOS app is unrunnable. If this could be top priority to fix please.

The outputted log: 2022-08-25 10:56:27.406805+1200 TMM[49043:1756968] Unhandled managed exception: Position 9:8. Type pages:InvertBooleanConverter not found in xmlns clr-namespace:<ProjectName>.Pages (Microsoft.Maui.Controls.Xaml.XamlParseException) at Microsoft.Maui.Controls.Xaml.CreateValuesVisitor.Visit(ElementNode , INode ) at Microsoft.Maui.Controls.Xaml.ElementNode.Accept(IXamlNodeVisitor , INode ) at Microsoft.Maui.Controls.Xaml.ElementNode.Accept(IXamlNodeVisitor , INode ) at Microsoft.Maui.Controls.Xaml.RootNode.Accept(IXamlNodeVisitor , INode ) at Microsoft.Maui.Controls.Xaml.XamlLoader.Visit(RootNode , HydrationContext , Boolean ) at Microsoft.Maui.Controls.Xaml.XamlLoader.Load(Object , String , Assembly , Boolean ) at Microsoft.Maui.Controls.Xaml.XamlLoader.Load(Object , String , Boolean ) at Microsoft.Maui.Controls.Xaml.XamlLoader.Load(Object , Type ) at Microsoft.Maui.Controls.Xaml.Extensions.LoadFromXaml[App](App , Type ) at TMM.App.InitializeComponent() in C:\Users\Documents\developmen t\Microsoft.Maui.Controls.SourceGen\Microsoft.Maui.Controls.SourceGen.CodeBehindGenerator\App.xaml.sg.cs:line 22 at TMM.App..ctor() in C:\Users\Documents\development\App.xaml.cs:line 16 at System.Reflection.RuntimeConstructorInfo.InternalInvoke(Object , Object[] , Boolean ) at System.Reflection.RuntimeConstructorInfo.DoInvoke(Object , BindingFlags , Binder , Object[] , CultureInfo ) at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags , Binder , Object[] , CultureInfo ) at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite , RuntimeResolverContext ) at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor2[[Microsoft.Extensions.DependencyInjection.ServiceLookup.RuntimeResolverContext, Microsoft.Extensions.DependencyInjection, Version=6.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60],[System.Object, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, Pu blicKeyToken=7cec85d7bea7798e]].VisitCallSiteMain(ServiceCallSite , RuntimeResolverContext ) at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitRootCache(ServiceCallSite , RuntimeResolverContext ) at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor2[[Microsoft.Extensions.DependencyInjection.ServiceLookup.RuntimeResolverContext, Microsoft.Extensions.DependencyInjection, Version=6.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60],[System.Object, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].VisitCallSite(ServiceCallSite , RuntimeResolverContext ) at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.Resolve(ServiceCallSite , ServiceProviderEngineScope ) at Microsoft.Extensions.DependencyInjection.ServiceProvider.CreateServiceAccessor(Type ) at System.Collections.Concurrent.ConcurrentDictionary2[[System.Type, System.Private.CoreLib, Version=6.0.0.0, Culture=n eutral, PublicKeyToken=7cec85d7bea7798e],[System.Func2[[Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope, Microsoft.Extensions.DependencyInjection, Version=6.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60],[System.Object, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]], System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].GetOrAdd(Type , Func2 ) at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(Type , ServiceProviderEngineScope ) at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(Type ) at Microsoft.Maui.MauiContext.WrappedServiceProvider.GetService(Type ) at Microsoft.Maui.MauiContext.WrappedServiceProvider.GetService(Type ) at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider , Type ) at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRe quiredServiceIApplication at Microsoft.Maui.MauiUIApplicationDelegate.FinishedLaunching(UIApplication , NSDictionary ) at UIKit.UIApplication.Main(String[] , Type , Type ) at <ProjectName>.Program.Main(String[] ) in C:\Users\Documents\development\Platforms\iOS\Program.cs:line 13`