[XC] Compile bindings with Source

[simonrozsival]

Description of Change

Currently, we're skipping compilation of bindings which have Source. The reason was that there wasn't support for relative binding sources until recently. Since #20415 has been merged into net9.0, we can now safely compile bindings which have a Source property.

Issues Fixed

Contributes to #20266

[StephaneDelcroix]

we can not start compiling Bindings with Source before we support x:DataType at the binding level, or we'll get issues with syntax like this

<Label x:Name="other" />
<Label x:DataType="viewModel" 
    Text={Binding foo} //binding on view model.foo
    TextColor={Binding TextColor, Source={x:Refererence other}} // will fail
/>

Also, in case the source can be determined (like x:Reference), we might not even need a DataType to proceed with compilation

[simonrozsival]

I'm not sure what exactly you mean. This binding is compiled correctly using the code in this branch:

<Label
    Text="{Binding Text, x:DataType=Button, Source={x:Reference CounterBtn}}"
    Style="{StaticResource SubHeadline}"
    SemanticProperties.HeadingLevel="Level2"
    SemanticProperties.Description="Welcome to dot net Multi platform App U I" />

<Button
    x:Name="CounterBtn"
    Text="Click me" 
    SemanticProperties.Hint="Counts the number of times you click"
    Clicked="OnCounterClicked"
    HorizontalOptions="Fill" />

Decompiled assembly:

// ...
referenceExtension.Name = "CounterBtn";
XamlServiceProvider xamlServiceProvider2 = new XamlServiceProvider();
Type typeFromHandle3 = typeof(IProvideValueTarget);
object[] array2 = new object[0 + 5];
array2[0] = bindingExtension;
array2[1] = label2;
array2[2] = verticalStackLayout;
array2[3] = scrollView;
array2[4] = mainPage;
object obj2;
xamlServiceProvider2.Add(typeFromHandle3, obj2 = new SimpleValueTargetProvider(array2, typeof(BindingExtension).GetRuntimeProperty("Source"), new NameScope[6] { nameScope, nameScope, nameScope, nameScope, nameScope, nameScope }, false));
xamlServiceProvider2.Add(typeof(IReferenceProvider), obj2);
Type typeFromHandle4 = typeof(IXamlTypeResolver);
XmlNamespaceResolver xmlNamespaceResolver2 = new XmlNamespaceResolver();
xmlNamespaceResolver2.Add("", "http://schemas.microsoft.com/dotnet/2021/maui");
xmlNamespaceResolver2.Add("x", "http://schemas.microsoft.com/winfx/2009/xaml");
xamlServiceProvider2.Add(typeFromHandle4, new XamlTypeResolver(xmlNamespaceResolver2, typeof(MainPage).Assembly));
xamlServiceProvider2.Add(typeof(IXmlLineInfoProvider), new XmlLineInfoProvider(new XmlLineInfo(22, 17)));
object source = ((IMarkupExtension)referenceExtension).ProvideValue((IServiceProvider)xamlServiceProvider2);
bindingExtension.Source = source;
bindingExtension.Path = "Text";
bindingExtension.TypedBinding = new TypedBinding<Button, string>((Button P_0) => (P_0 != null) ? (P_0.Text, true) : default((string, bool)), delegate(Button P_0, string P_1)
{
    if (P_0 != null)
    {
        P_0.Text = P_1;
    }
}, new Tuple<Func<Button, object>, string>[1]
{
    new Tuple<Func<Button, object>, string>((Button P_0) => P_0, "Text")
});
BindingBase binding = ((IMarkupExtension<BindingBase>)bindingExtension).ProvideValue((IServiceProvider)null);
label2.SetBinding(Label.TextProperty, binding);
// ...

Also, in case the source can be determined (like x:Reference), we might not even need a DataType to proceed with compilation

I agree that that should be supported as well. But I think that could be implemented in a separate PR.

[simonrozsival]

BTW looking at the decompiled code more closely, it doesn't seem we don't compile the x:Reference markup extensions at all so we aren't able to determine the type of the source at the moment. At the same time, in this case it should be trivial to compile the reference, so I'm a bit surprised we don't do that.

[rmarinho]

Build is failing for windows. Also if you can rebase :)

Issue9417.xaml(43,37): XamlC error XFC0045: Binding: Property "BindingContext" not found on "Microsoft.Maui.Controls.ControlGallery.Issues.Issue9417Model". [D:\a\_work\1\s\src\Compatibility\ControlGallery\src\Core\Compatibility.ControlGallery.Core.csproj]
Issue11764.xaml(29,37): XamlC error XFC0045: Binding: Property "BindingContext" not found on "System.String". [D:\a\_work\1\s\src\Compatibility\ControlGallery\src\Core\Compatibility.ControlGallery.Core.csproj]
Issue11831.xaml(57,41): XamlC error XFC0045: Binding: Property "BindingContext" not found on "System.String". [D:\a\_work\1\s\src\Compatibility\ControlGallery\src\Core\Compatibility.ControlGallery.Core.csproj]
    7010 Warning(s)
    3 Error(s)

[simonrozsival]

@rmarinho the remaining failing tests seem to be unrelated