[C] Fix binding to interface-inherited properties like IReadOnlyList<T>.Count#32912
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rmarinho merged 2 commits intoinflight/currentfrom Dec 5, 2025
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…ount Fixes #13872 The runtime binding expression was not resolving properties inherited from parent interfaces. For example, IReadOnlyList<T>.Count would return null because Count is defined on IReadOnlyCollection<T>, not directly on IReadOnlyList<T>. Added GetProperty() method that searches both base classes and implemented interfaces recursively, similar to how GetIndexer() already handles this case.
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Pull request overview
This PR fixes a bug where runtime bindings failed to resolve properties inherited from parent interfaces. For example, IReadOnlyList<T>.Count would return null because the Count property is defined on IReadOnlyCollection<T>, not directly on IReadOnlyList<T>.
Key changes:
- Added recursive interface search capability to property resolution in runtime bindings
- Refactored property lookup logic into a dedicated
GetProperty()method that mirrors the existingGetIndexer()pattern - Added comprehensive test coverage for the fix across all XAML inflators
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| src/Controls/src/Core/BindingExpression.cs | Adds GetProperty() method with recursive interface search and refactors SetupPart() to use it instead of inline property lookup |
| src/Controls/tests/Xaml.UnitTests/Issues/Maui13872.xaml | XAML test file demonstrating both compiled and uncompiled bindings to IReadOnlyList<T>.Count |
| src/Controls/tests/Xaml.UnitTests/Issues/Maui13872.xaml.cs | Test code-behind with view model and test assertions validating the fix works with all inflators |
StephaneDelcroix
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…T>.Count (#32912) * Fix binding to interface-inherited properties like IReadOnlyList<T>.Count Fixes #13872 The runtime binding expression was not resolving properties inherited from parent interfaces. For example, IReadOnlyList<T>.Count would return null because Count is defined on IReadOnlyCollection<T>, not directly on IReadOnlyList<T>. Added GetProperty() method that searches both base classes and implemented interfaces recursively, similar to how GetIndexer() already handles this case. * Fix Maui32879Tests expected output after pragma warning merge
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…T>.Count (#32912) * Fix binding to interface-inherited properties like IReadOnlyList<T>.Count Fixes #13872 The runtime binding expression was not resolving properties inherited from parent interfaces. For example, IReadOnlyList<T>.Count would return null because Count is defined on IReadOnlyCollection<T>, not directly on IReadOnlyList<T>. Added GetProperty() method that searches both base classes and implemented interfaces recursively, similar to how GetIndexer() already handles this case. * Fix Maui32879Tests expected output after pragma warning merge
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…T>.Count (#32912) * Fix binding to interface-inherited properties like IReadOnlyList<T>.Count Fixes #13872 The runtime binding expression was not resolving properties inherited from parent interfaces. For example, IReadOnlyList<T>.Count would return null because Count is defined on IReadOnlyCollection<T>, not directly on IReadOnlyList<T>. Added GetProperty() method that searches both base classes and implemented interfaces recursively, similar to how GetIndexer() already handles this case. * Fix Maui32879Tests expected output after pragma warning merge
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…T>.Count (#32912) * Fix binding to interface-inherited properties like IReadOnlyList<T>.Count Fixes #13872 The runtime binding expression was not resolving properties inherited from parent interfaces. For example, IReadOnlyList<T>.Count would return null because Count is defined on IReadOnlyCollection<T>, not directly on IReadOnlyList<T>. Added GetProperty() method that searches both base classes and implemented interfaces recursively, similar to how GetIndexer() already handles this case. * Fix Maui32879Tests expected output after pragma warning merge
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…T>.Count (#32912) * Fix binding to interface-inherited properties like IReadOnlyList<T>.Count Fixes #13872 The runtime binding expression was not resolving properties inherited from parent interfaces. For example, IReadOnlyList<T>.Count would return null because Count is defined on IReadOnlyCollection<T>, not directly on IReadOnlyList<T>. Added GetProperty() method that searches both base classes and implemented interfaces recursively, similar to how GetIndexer() already handles this case. * Fix Maui32879Tests expected output after pragma warning merge
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…T>.Count (#32912) * Fix binding to interface-inherited properties like IReadOnlyList<T>.Count Fixes #13872 The runtime binding expression was not resolving properties inherited from parent interfaces. For example, IReadOnlyList<T>.Count would return null because Count is defined on IReadOnlyCollection<T>, not directly on IReadOnlyList<T>. Added GetProperty() method that searches both base classes and implemented interfaces recursively, similar to how GetIndexer() already handles this case. * Fix Maui32879Tests expected output after pragma warning merge
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…T>.Count (#32912) * Fix binding to interface-inherited properties like IReadOnlyList<T>.Count Fixes #13872 The runtime binding expression was not resolving properties inherited from parent interfaces. For example, IReadOnlyList<T>.Count would return null because Count is defined on IReadOnlyCollection<T>, not directly on IReadOnlyList<T>. Added GetProperty() method that searches both base classes and implemented interfaces recursively, similar to how GetIndexer() already handles this case. * Fix Maui32879Tests expected output after pragma warning merge
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Dec 26, 2025
…T>.Count (#32912) * Fix binding to interface-inherited properties like IReadOnlyList<T>.Count Fixes #13872 The runtime binding expression was not resolving properties inherited from parent interfaces. For example, IReadOnlyList<T>.Count would return null because Count is defined on IReadOnlyCollection<T>, not directly on IReadOnlyList<T>. Added GetProperty() method that searches both base classes and implemented interfaces recursively, similar to how GetIndexer() already handles this case. * Fix Maui32879Tests expected output after pragma warning merge
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…T>.Count (#32912) * Fix binding to interface-inherited properties like IReadOnlyList<T>.Count Fixes #13872 The runtime binding expression was not resolving properties inherited from parent interfaces. For example, IReadOnlyList<T>.Count would return null because Count is defined on IReadOnlyCollection<T>, not directly on IReadOnlyList<T>. Added GetProperty() method that searches both base classes and implemented interfaces recursively, similar to how GetIndexer() already handles this case. * Fix Maui32879Tests expected output after pragma warning merge
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## CollectionView - Fixed the NRE in CarouselViewController on iOS 15.5 & 16.4 by @Ahamed-Ali in #30838 <details> <summary>🔧 Fixes</summary> - [NRE in CarouselViewController on iOS 15.5 & 16.4](#28557) </details> - [iOS, macOS] Fixed CollectionView group header size changes with ItemSizingStrategy by @NanthiniMahalingam in #33161 <details> <summary>🔧 Fixes</summary> - [[NET 10] I6_Grouping - Grouping_with_variable_sized_items changing the 'ItemSizingStrategy' also changes the header size.](#33130) </details> ## Flyout - Add unit tests for TabBar and FlyoutItem navigation ApplyQueryAttributes (#25663) by @StephaneDelcroix in #33006 ## Flyoutpage - Fixed the FlyoutPage.Flyout Disappearing When Maximizing the Window on Mac Platform by @NanthiniMahalingam in #26701 <details> <summary>🔧 Fixes</summary> - [FlyoutPage.Flyout - navigation corrupted when running om mac , on window ok](#22719) </details> ## Mediapicker - [Windows] Fix for PickPhotosAsync throws exception if image is modified by @HarishwaranVijayakumar in #32952 <details> <summary>🔧 Fixes</summary> - [PickPhotosAsync throws exception if image is modified.](#32408) </details> ## Navigation - Fix for TabBar Navigation does not invoke its IQueryAttributable.ApplyQueryAttributes(query) by @SuthiYuvaraj in #25663 <details> <summary>🔧 Fixes</summary> - [Tabs defined in AppShell.xaml does not invoke its view model's IQueryAttributable.ApplyQueryAttributes(query) implementaion](#13537) - [`ShellContent` routes do not call `ApplyQueryAttributes`](#28453) </details> ## ScrollView - Fix ScrollToPosition.Center behavior in ScrollView on iOS and MacCatalyst by @devanathan-vaithiyanathan in #26825 <details> <summary>🔧 Fixes</summary> - [ScrollToPosition.Center Centers the First Item too in iOS and Catalyst](#26760) - [On iOS - ScrollView.ScrollToAsync Element, ScrollToPosition.MakeVisible shifts view to the right, instead of just scrolling vertically](#28965) </details> ## Searchbar - [iOS, Mac, Windows] Fixed CharacterSpacing for SearchBar text and placeholder text by @Dhivya-SF4094 in #30407 <details> <summary>🔧 Fixes</summary> - [[iOS, Mac, Windows] SearchBar CharacterSpacing property is not working as expected](#30366) </details> ## Shell - Update logic for large title display mode on iOS - shell by @kubaflo in #33039 ## TitleView - [iOS] Fixed memory leak with PopToRootAsync when using TitleView by @Vignesh-SF3580 in #28547 <details> <summary>🔧 Fixes</summary> - [NavigationPage.TitleView causes memory leak with PopToRootAsync](#28201) </details> ## Xaml - [C] Fix binding to interface-inherited properties like IReadOnlyList<T>.Count by @StephaneDelcroix in #32912 <details> <summary>🔧 Fixes</summary> - [Compiled Binding to Array.Count provides no result](#13872) </details> - Fix #31939: CommandParameter TemplateBinding lost during reparenting by @StephaneDelcroix in #32961 <details> <summary>🔧 Fixes</summary> - [CommandParameter TemplateBinding Lost During ControlTemplate Reparenting](#31939) </details> <details> <summary>🧪 Testing (4)</summary> - [Testing] Fixed Test case failure in PR 33185 - [12/22/2025] Candidate by @TamilarasanSF4853 in #33257 - [Testing] Re-saved ShouldFlyoutBeVisibleAfterMaximizingWindow test case images in PR 33185 - [12/22/2025] Candidate by @TamilarasanSF4853 in #33271 - [Testing] Fixed Test case failure in PR 33185 - [12/22/2025] Candidate - 2 by @TamilarasanSF4853 in #33299 - [Testing] Fixed Test case failure in PR 33185 - [12/22/2025] Candidate - 3 by @TamilarasanSF4853 in #33311 </details> <details> <summary>📦 Other (2)</summary> - [XSG][BindingSourceGen] Add support for RelayCommand to compiled bindings by @simonrozsival via @Copilot in #32954 <details> <summary>🔧 Fixes</summary> - [Issue #25818](#25818) </details> - Revert "Update logic for large title display mode on iOS - shell (#33039)" in cff7f35 </details> **Full Changelog**: main...inflight/candidate
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Description
Fixes #13872
Runtime bindings were not resolving properties inherited from parent interfaces. For example,
IReadOnlyList<T>.Countwould returnnullbecauseCountis defined onIReadOnlyCollection<T>, not directly onIReadOnlyList<T>.Changes
GetProperty()method inBindingExpression.csthat searches both base classes and implemented interfaces recursively (similar to howGetIndexer()already handles this case)SetupPart()to use the newGetProperty()methodMaui13872that verifies bindings toIReadOnlyList<T>.Countwork correctly with all XAML inflators (Runtime, XamlC, SourceGen)Test Results
All 1790 XAML unit tests pass: