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fix: SettingsPage NativeAOT crash — use BindableSelectionItem with [GeneratedBindableCustomProperty]#118

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copilot/sub-pr-116
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fix: SettingsPage NativeAOT crash — use BindableSelectionItem with [GeneratedBindableCustomProperty]#118
Copilot wants to merge 3 commits intofeat/aotfrom
copilot/sub-pr-116

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Copilot AI commented Mar 20, 2026

The previous NativeAOT fix introduced x:DataType="desktopapp:ISelectionItem" compiled bindings for the theme/language ComboBoxes. SelectionItem<T> and ISelectionItem from Nickvision.Desktop lack [GeneratedBindableCustomProperty], causing WinUI's binding infrastructure to throw System.ArgumentException: 'Value does not fall within the expected range.' at ItemsSource assignment time.

[WinRT.GeneratedBindableCustomProperty] cannot be added to external package types — it must be applied to a partial type declaration that the CsWinRT source generator owns at compile time. The solution is to define a local BindableSelectionItem class in the WinUI project itself.

Changes

  • New Models/BindableSelectionItem.cs: A sealed partial class decorated with [WinRT.GeneratedBindableCustomProperty], exposing a string Label property. The CsWinRT source generator (included via Microsoft.WindowsAppSDK) emits the WinRT vtable at compile time, making it fully NativeAOT-safe for XAML compiled bindings.
  • SettingsPage.xaml: Added xmlns:models namespace; restored ItemTemplate DataTemplates on both ComboBoxes using x:DataType="models:BindableSelectionItem" with {x:Bind Label} compiled binding.
  • SettingsPage.xaml.cs:
    • Set ItemsSource to List<BindableSelectionItem> (wrapping labels from SelectionItem<T>) — NativeAOT-compatible, no WMC1510 warnings.
    • Replace SelectSelectionItem() extension calls in Page_Loaded with explicit index loops on ShouldSelect.
    • Replace SelectedItem as SelectionItem<T> casts in ApplyChangesAsync with SelectedIndex-based indexing into the controller's original collections.
    • Add SelectedIndex < 0 guard in ApplyChangesAsync.
    • Remove now-unused using directives (Nickvision.Desktop.Application, Nickvision.Desktop.WinUI.Helpers, Nickvision.Application.Shared.Models).
// BindableSelectionItem — owned by this project, source-generated WinRT vtable
[GeneratedBindableCustomProperty]
public sealed partial class BindableSelectionItem(string label)
{
    public string Label { get; } = label;
}

// ItemsSource uses BindableSelectionItem; index maps back to original SelectionItem<T>
CmbTheme.ItemsSource = _controller.Themes.Select(t => new BindableSelectionItem(t.Label)).ToList();
// ...
_controller.Theme = _controller.Themes[CmbTheme.SelectedIndex];

Eliminates WMC1510 trimming warnings on the ComboBoxes — {x:Bind Label} on a [GeneratedBindableCustomProperty] type is fully compiled and AOT-safe.


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…d SelectedIndex

Co-authored-by: nlogozzo <17648453+nlogozzo@users.noreply.github.com>
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Copilot AI commented Mar 20, 2026

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

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Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

  • crl.godaddy.com
    • Triggering command: /usr/bin/dotnet dotnet restore --no-dependencies /tmp/codeql-scratch-297de09d6e55df2d/dbs/csharp/working/7F0AD5B89EC078FE77CFD6BDA2F52E08/missingpackages_workingdir --packages /tmp/codeql-scratch-297de09d6e55df2d/dbs/csharp/working/missingpackages /p:DisableImplicitNuGetFallbackFolder=true --verbosity normal --configfile /tmp/codeql-scratch-297de09d6e55df2d/dbs/csharp/working/nugetconfig/nuget.config --force (dns block)
  • ocsp.godaddy.com
    • Triggering command: /usr/bin/dotnet dotnet restore --no-dependencies /tmp/codeql-scratch-297de09d6e55df2d/dbs/csharp/working/7F0AD5B89EC078FE77CFD6BDA2F52E08/missingpackages_workingdir --packages /tmp/codeql-scratch-297de09d6e55df2d/dbs/csharp/working/missingpackages /p:DisableImplicitNuGetFallbackFolder=true --verbosity normal --configfile /tmp/codeql-scratch-297de09d6e55df2d/dbs/csharp/working/nugetconfig/nuget.config --force (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

Copilot AI changed the title [WIP] Fix WinUI settings page crash in NativeAOT compiled app fix: SettingsPage NativeAOT crash — replace DataTemplate x:DataType with string ItemsSource Mar 20, 2026
Copilot AI requested a review from nlogozzo March 20, 2026 17:42
@nlogozzo
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@copilot How can I add GeneratedBindableCustomProperty to these nickvision.desktop properties? It's not a WinUI project Nickvision.Destkop. Can we add extensions here to support it, instead of removing it. I want to use itemsource and not create new items

… for NativeAOT XAML binding

Co-authored-by: nlogozzo <17648453+nlogozzo@users.noreply.github.com>
Agent-Logs-Url: https://github.com/NickvisionApps/Application/sessions/105ab25b-0724-40f1-ac0e-3ca2799eb7f8
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Copilot AI commented Mar 20, 2026

@copilot How can I add GeneratedBindableCustomProperty to these nickvision.desktop properties? It's not a WinUI project Nickvision.Destkop. Can we add extensions here to support it, ...

You cannot add [GeneratedBindableCustomProperty] directly to types in external packages like Nickvision.Desktop — the attribute must be on a partial type declaration that the CsWinRT source generator can reach at compile time to emit the WinRT vtable code. It's not something that can be added via extensions or assembly-level attributes.

The solution (commit df5445b) is to create a BindableSelectionItem sealed partial class in the WinUI project itself with [WinRT.GeneratedBindableCustomProperty]:

// Models/BindableSelectionItem.cs
[GeneratedBindableCustomProperty]
public sealed partial class BindableSelectionItem(string label)
{
    public string Label { get; } = label;
}

The SettingsPage then builds a List<BindableSelectionItem> from the controller's SelectionItem<T> data for ItemsSource, and the DataTemplate uses x:DataType="models:BindableSelectionItem" with {x:Bind Label} — a fully compiled, NativeAOT-safe binding with no WMC1510 warnings. The SelectedIndex still maps back to the original SelectionItem<T> in ApplyChangesAsync.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

  • crl.godaddy.com
    • Triggering command: /usr/bin/dotnet dotnet restore --no-dependencies /tmp/codeql-scratch-297de09d6e55df2d/dbs/csharp/working/1D28AAEF2CB9C63BCE9DBD21A68FB8D9/missingpackages_workingdir --packages /tmp/codeql-scratch-297de09d6e55df2d/dbs/csharp/working/missingpackages /p:DisableImplicitNuGetFallbackFolder=true --verbosity normal --configfile /tmp/codeql-scratch-297de09d6e55df2d/dbs/csharp/working/nugetconfig/nuget.config --force n-x8�� eCustomProperty strings gers.dll eCustomProperty strings ion.Formatters.d2465fe388a4704b683faee10d881ceb519fa8cb0:Nickvision.Application.WinUI/Models/BindableSelectionItem.cs strings (dns block)
  • ocsp.godaddy.com
    • Triggering command: /usr/bin/dotnet dotnet restore --no-dependencies /tmp/codeql-scratch-297de09d6e55df2d/dbs/csharp/working/1D28AAEF2CB9C63BCE9DBD21A68FB8D9/missingpackages_workingdir --packages /tmp/codeql-scratch-297de09d6e55df2d/dbs/csharp/working/missingpackages /p:DisableImplicitNuGetFallbackFolder=true --verbosity normal --configfile /tmp/codeql-scratch-297de09d6e55df2d/dbs/csharp/working/nugetconfig/nuget.config --force n-x8�� eCustomProperty strings gers.dll eCustomProperty strings ion.Formatters.d2465fe388a4704b683faee10d881ceb519fa8cb0:Nickvision.Application.WinUI/Models/BindableSelectionItem.cs strings (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

Copilot AI changed the title fix: SettingsPage NativeAOT crash — replace DataTemplate x:DataType with string ItemsSource fix: SettingsPage NativeAOT crash — use BindableSelectionItem with [GeneratedBindableCustomProperty] Mar 20, 2026
@nlogozzo
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@copilot I own Nickvision.Desktop and Nickvision.Desktop.WinUI. Would it work if I added this to the WinUI project:

using Nickvision.Desktop.Application;
using WinRT;

namespace Nickvision.Desktop.WinUI.Helpers;

[GeneratedBindableCustomProperty]
public sealed partial class BindableSelectionItem<T>
{
    private readonly SelectionItem<T> _selectionItem;

    public BindableSelectionItem(SelectionItem<T> selectionItem)
    {
        _selectionItem = selectionItem;
    }

    public static implicit operator SelectionItem<T>(BindableSelectionItem<T> bindableSelectionItem) => bindableSelectionItem;

    public static implicit operator BindableSelectionItem<T>(SelectionItem<T> selectionItem) => new BindableSelectionItem<T>(selectionItem);
}

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Copilot AI commented Mar 20, 2026

@copilot I own Nickvision.Desktop and Nickvision.Desktop.WinUI. Would it work if I added this to the WinUI project:

using Nickvision.Desktop.Application;

...

Yes, that approach would work in Nickvision.Desktop.WinUI with two adjustments:

  1. Wrap ISelectionItem, not SelectionItem<T> — XAML x:DataType cannot handle open generic types, so the wrapper must be a non-generic concrete class. ISelectionItem (which SelectionItem<T> already implements) is the right base.

  2. Expose Label as a public property[GeneratedBindableCustomProperty] only generates vtable entries for public properties. Without a public Label, the {x:Bind Label} in the DataTemplate would have nothing to bind to.

Here's what it would look like:

using Nickvision.Desktop.Application;
using WinRT;

namespace Nickvision.Desktop.WinUI.Helpers;

[GeneratedBindableCustomProperty]
public sealed partial class BindableSelectionItem
{
    private readonly ISelectionItem _selectionItem;

    public BindableSelectionItem(ISelectionItem selectionItem)
    {
        _selectionItem = selectionItem;
    }

    public string Label => _selectionItem.Label;
    public bool ShouldSelect => _selectionItem.ShouldSelect;

    public static implicit operator BindableSelectionItem(SelectionItem<object> item) => new(item);
}

Note on the implicit operators: Generic implicit operators (SelectionItem<T>BindableSelectionItem) aren't supported in C# — they'd have to be per-concrete-type. The cast from ISelectionItem works fine since every SelectionItem<T> implements it.

Once you publish a new Nickvision.Desktop.WinUI version with this class, this project can switch to use it. The current local Models/BindableSelectionItem.cs is structurally identical and fully functional in the meantime.

@nlogozzo nlogozzo closed this Mar 20, 2026
@nlogozzo nlogozzo deleted the copilot/sub-pr-116 branch March 20, 2026 18:39
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