[X] Optionally stop supporting Namescopes #30435
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With Xaml SourceGen, Namescopes are no longer necessary for the XAML infrastructure. Npt generating them will help the JIT and GC This is mostly unused right now - fixes #30434
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Pull Request Overview
This PR introduces an optional runtime switch to disable XAML namescopes support, improving JIT and GC behavior when namescopes aren’t necessary.
- Adds
AreNamescopesSupportedfeature switch and default inRuntimeFeature.cs - Injects guard clauses throwing if namescopes are disabled across XAML and runtime namescope APIs
- Updates MSBuild targets and documentation for the new switch
Reviewed Changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| src/Core/src/RuntimeFeature.cs | Added SupportNamescopesByDefault and AreNamescopesSupported switch; exposed feature properties publicly |
| src/Controls/src/Xaml/XamlServiceProvider.cs | Guard FindByName calls with AreNamescopesSupported check |
| src/Controls/src/Core/NameScopeExtensions.cs | Added guard in extension and namescope helper overload |
| src/Controls/src/Core/Internals/NameScope.cs | Added guard clauses in INameScope implementations |
| src/Controls/src/Core/Element/Element.cs | Added guard clauses in FindByName, register/unregister, GetNameScope |
| src/Controls/src/Build.Tasks/nuget/.../Microsoft.Maui.Controls.targets | Added MSBuild RuntimeHostConfigurationOption for namescopes |
| docs/design/FeatureSwitches.md | Documented new MauiNamescopesSupported switch; updated feature table |
Comments suppressed due to low confidence (2)
docs/design/FeatureSwitches.md:14
- The switch key in the table ('Microsoft.Maui.RuntimeFeature.XamlCBindingWithSourceCompilationEnabled') is missing the 'Is' prefix present in the code; please align key names with the actual feature switch identifiers.
| MauiEnableXamlCBindingWithSourceCompilation | Microsoft.Maui.RuntimeFeature.XamlCBindingWithSourceCompilationEnabled | When enabled, MAUI will compile all bindings, including those where the `Source` property is used. |
src/Controls/src/Xaml/XamlServiceProvider.cs:177
- New guard clauses are introduced for the namescopes feature; consider adding unit tests or UI tests in TestCases.Shared.Tests and TestCases.HostApp to cover both enabled and disabled scenarios.
if (!RuntimeFeature.AreNamescopesSupported)
simonrozsival
previously approved these changes
Jul 4, 2025
StephaneDelcroix
commented
Jul 4, 2025
|
failures unrelated |
simonrozsival
approved these changes
Jul 14, 2025
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Description of Change
With Xaml SourceGen, Namescopes are no longer necessary for the XAML infrastructure. Npt generating them will help the JIT and GC
This is mostly unused right now
Issues Fixed