MarkupExtension instance is not properly kept alive

[Xiaoy312]

Current behavior

Currently on uno, MarkupExtension is used like a oneshot value-provider:

xaml: <TextBlock Text="{local:TestAsdExtensions}" />
generated:
new global::Microsoft.UI.Xaml.Controls.TextBlock { IsParsing = true, /*...*/ }
.GenericApply(__that, __nameScope, ((c0, __that, __nameScope) =>
{
	c0.Text = (string)Convert.ChangeType(
		(((global::Microsoft.UI.Xaml.Markup.IMarkupExtensionOverrides)new global::MarkupExtLifetime.TestAsdExtensions())
			.ProvideValue(global::Uno.UI.Helpers.MarkupHelper.CreateParserContext(
				c0, 
				typeof(global::Microsoft.UI.Xaml.Controls.TextBlock), 
				"Text", 
				typeof(object)
		)))?.ToString(), 
		typeof(string)
	);
	//...
}))

the instance dies immediately

Expected behavior

the markup instance should be kept alive for at least the duration of its owner's lifetime.

How to reproduce it (as minimally and precisely as possible)

MarkupExtLifetime.zip

1. click on "Test" button
2. notice the text is updated
   ^ different result when comparing uno to windows

Workaround

keep a hard reference of markup-instance, and clear that when the owning target is removed from the visual-tree

Works on UWP/WinUI

Yes

Environment

Uno.WinUI / Uno.WinUI.WebAssembly / Uno.WinUI.Skia

NuGet package version(s)

Uno.WinUI@5.0.41

Affected platforms

WebAssembly, Android, iOS, Skia (WPF)

IDE

No response

IDE version

No response

Relevant plugins

No response

Anything else we need to know?

on windows, it is unclear yet what the exact lifetime would be, but it seems to even outlive the TextBlock?
for context, it lived past this:

if (Content is StackPanel sp &&
	sp.Children.FirstOrDefault(x => x is TextBlock) is TextBlock tb)
{
	sp.Children.Remove(tb);

	GC.Collect();
	GC.Collect();
}

[kazo0]

@Xiaoy312 would this be something that we could check in the WinUI sources for how it's done?

[Xiaoy312]

Just documenting something really weird that I found..:

Previously we had a workaround by keeping a hard self-reference in the instance itself. This has worked with great success:

public partial class ResponsiveExtension {
	private ResponsiveExtension? _selfHardReference;
	public ResponsiveExtension() => _selfHardReference = this;

However, it seems that with certain case, like on ColumnDefinition, it would randomly fail (not guarantee but at 50/50 odd..? between full app restarts).
After I made some change, and the issue is completely gone for all the cases I was testing for:

public partial class ResponsiveExtension {
	private static List<ResponsiveExtension> HardSelfReferences { get; } = new();
	public ResponsiveExtension() => HardSelfReferences.Add(this);