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[XSG] Fix incorrect TargetNullValue flag check causing NPE with nullable bindings #32580

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Merged
simonrozsival merged 9 commits into from
Nov 25, 2025
Merged

[XSG] Fix incorrect TargetNullValue flag check causing NPE with nullable bindings #32580

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0b60a63
Initial plan
Copilot Nov 13, 2025
a5dfdf7
Fix TargetNullValue bug and enable compilation validation in tests
Copilot Nov 13, 2025
603c9f0
Clean up debug code and finalize tests
Copilot Nov 13, 2025
717c9bc
Simplify test infrastructure per code review feedback
Copilot Nov 13, 2025
75ac41a
Improve asserting no compilation errors in generated code
simonrozsival Nov 13, 2025
7ae2d52
Fix SourceGen.UnitTests compilation error
StephaneDelcroix Nov 19, 2025
752fd8b
Fix XStaticUnresolvedType tests by disabling compilation validation
StephaneDelcroix Nov 20, 2025
3267d25
Fix XStaticUnresolvedType tests to validate compilation with stub types
Copilot Nov 20, 2025
1048452
Simplify XStaticUnresolvedType tests by including stub types in code …
Copilot Nov 20, 2025
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2 changes: 1 addition & 1 deletion src/Controls/src/SourceGen/CompiledBindingMarkup.cs
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Expand Up @@ -178,7 +178,7 @@ public bool TryCompileBinding(ITypeSymbol sourceType, bool isTemplateBinding, ou
// TypedBinding creation
code.WriteLine($"return new global::Microsoft.Maui.Controls.Internals.TypedBinding<{binding.SourceType}, {binding.PropertyType}>(");
code.Indent++;
var targetNullValueExpression = isTemplateBinding || !propertyFlags.HasFlag(BindingPropertyFlags.FallbackValue) ? null : "extension.TargetNullValue";
var targetNullValueExpression = isTemplateBinding || !propertyFlags.HasFlag(BindingPropertyFlags.TargetNullValue) ? null : "extension.TargetNullValue";
code.WriteLine($"getter: source => ({GenerateGetterExpression(binding, sourceVariableName: "source", targetNullValueExpression)}, true),");
code.WriteLine("setter,");
code.Write("handlers: ");
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2 changes: 1 addition & 1 deletion src/Controls/src/SourceGen/KnownMarkups.cs
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Expand Up @@ -214,7 +214,7 @@ internal static bool ProvideValueForStyleSheetExtension(ElementNode markupNode,
else // sourceNode != null
{
var source = (string)(sourceNode as ValueNode)!.Value;
var uri = $"new global::System.Uri(\"{source}\", global::System.UriKind.Relative)";
var uri = $"new global::System.Uri(@\"{source}\", global::System.UriKind.Relative)";
var rootTargetPath = $"global::Microsoft.Maui.Controls.Xaml.XamlResourceIdAttribute.GetPathForType(typeof({context.RootType.ToFQDisplayString()}))";

var resourcePath = $"global::Microsoft.Maui.Controls.ResourceDictionary.RDSourceTypeConverter.GetResourcePath({uri}, {rootTargetPath})";
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2 changes: 1 addition & 1 deletion src/Controls/src/SourceGen/NodeSGExtensions.cs
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Expand Up @@ -447,7 +447,7 @@ void reportDiagnostic()
reportDiagnostic();
}
if (toType.Equals(context.Compilation.GetTypeByMetadataName("System.Uri")!, SymbolEqualityComparer.Default))
return $"new global::System.Uri(\"{valueString}\", global::System.UriKind.RelativeOrAbsolute)";
return $"new global::System.Uri(@\"{valueString}\", global::System.UriKind.RelativeOrAbsolute)";

//default
return SymbolDisplay.FormatLiteral(valueString, true);
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4 changes: 2 additions & 2 deletions src/Controls/src/SourceGen/TypeConverters/RDSourceConverter.cs
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Expand Up @@ -61,7 +61,7 @@ static string GetResourcePath(string value, string rootTargetPath)

var uriType = context.Compilation.GetTypeByMetadataName("System.Uri")!;
var uriKindType = context.Compilation.GetTypeByMetadataName("System.UriKind")!;
writer.WriteLine($"var {uriVar} = new {uriType.ToFQDisplayString()}(\"{value};assembly={asm.Name}\", {uriKindType.ToFQDisplayString()}.RelativeOrAbsolute);");
writer.WriteLine($"var {uriVar} = new {uriType.ToFQDisplayString()}(@\"{value};assembly={asm.Name}\", {uriKindType.ToFQDisplayString()}.RelativeOrAbsolute);");

var rootTargetPath = context.ProjectItem.RelativePath!.Replace('\\', '/');

Expand All @@ -76,7 +76,7 @@ static string GetResourcePath(string value, string rootTargetPath)
else
{
var resourceDictionaryHelpersType = context.Compilation.GetTypeByMetadataName("Microsoft.Maui.Controls.Xaml.ResourceDictionaryHelpers")!;
writer.WriteLine($"{resourceDictionaryHelpersType.ToFQDisplayString()}.LoadFromSource({parentVar.ValueAccessor}, {uriVar}, \"{GetResourcePath(value, rootTargetPath)}\", typeof({context.RootType.ToFQDisplayString()}).Assembly, null);");
writer.WriteLine($"{resourceDictionaryHelpersType.ToFQDisplayString()}.LoadFromSource({parentVar.ValueAccessor}, {uriVar}, @\"{GetResourcePath(value, rootTargetPath)}\", typeof({context.RootType.ToFQDisplayString()}).Assembly, null);");
}

return uriVar;
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2 changes: 1 addition & 1 deletion src/Controls/tests/SourceGen.UnitTests/InitializeComponent/CircularReferenceExtension.cs
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Expand Up @@ -155,7 +155,7 @@ public BugPage()

// Run generator with BOTH files at once - this creates the shared context
// that triggers the infinite loop with the buggy code
var result = RunGenerator<XamlGenerator>(compilation, expanderFile, bugFile);
var result = RunGenerator<XamlGenerator>(compilation, [expanderFile, bugFile]);

return result;
}, cts.Token);
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150 changes: 150 additions & 0 deletions src/Controls/tests/SourceGen.UnitTests/InitializeComponent/CompiledBindings.cs
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Expand Up @@ -489,6 +489,156 @@ public class Product
Assert.False(result.Diagnostics.Any(d => d.Severity == Microsoft.CodeAnalysis.DiagnosticSeverity.Error));
}

[Fact]
public void TargetNullValueWithNullablePathGeneratesValidCode()
{
// This test reproduces the issue from #32606 where TargetNullValue with nullable path
// generates invalid code: getter references extension.TargetNullValue but cannot be static
var xaml =
"""
<?xml version="1.0" encoding="UTF-8"?>
<ContentPage
xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:test="clr-namespace:Test"
x:Class="Test.TestPage"
x:DataType="test:TestPage">
<Label Text="{Binding CurrentPerson.Id, TargetNullValue=0}"/>
</ContentPage>
""";

var code =
"""
#nullable enable
using System;
using Microsoft.Maui.Controls;
using Microsoft.Maui.Controls.Xaml;

namespace Test;

[XamlProcessing(XamlInflator.SourceGen)]
public partial class TestPage : ContentPage
{
public Person? CurrentPerson { get; set; } = null;

public TestPage()
{
InitializeComponent();
}
}

public class Person
{
public int Id { get; set; }
}
""";
var testXamlFilePath = Path.Combine(Environment.CurrentDirectory, "Test.xaml");
var expected = $$"""
//------------------------------------------------------------------------------
// <auto-generated>
// This code was generated by a .NET MAUI source generator.
//
// Changes to this file may cause incorrect behavior and will be lost if
// the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------
#nullable enable

namespace Test;

[global::System.CodeDom.Compiler.GeneratedCodeAttribute("Microsoft.Maui.Controls.SourceGen, Version=10.0.0.0, Culture=neutral, PublicKeyToken=null", "10.0.0.0")]
public partial class TestPage
{
private partial void InitializeComponent()
{
// Fallback to Runtime inflation if the page was updated by HotReload
static string? getPathForType(global::System.Type type)
{
var assembly = type.Assembly;
foreach (var xria in global::System.Reflection.CustomAttributeExtensions.GetCustomAttributes<global::Microsoft.Maui.Controls.Xaml.XamlResourceIdAttribute>(assembly))
{
if (xria.Type == type)
return xria.Path;
}
return null;
}

var rlr = global::Microsoft.Maui.Controls.Internals.ResourceLoader.ResourceProvider2?.Invoke(new global::Microsoft.Maui.Controls.Internals.ResourceLoader.ResourceLoadingQuery
{
AssemblyName = typeof(global::Test.TestPage).Assembly.GetName(),
ResourcePath = getPathForType(typeof(global::Test.TestPage)),
Instance = this,
});

if (rlr?.ResourceContent != null)
{
this.InitializeComponentRuntime();
return;
}

var bindingExtension = new global::Microsoft.Maui.Controls.Xaml.BindingExtension();
global::Microsoft.Maui.VisualDiagnostics.RegisterSourceInfo(bindingExtension!, new global::System.Uri(@"Test.xaml;assembly=SourceGeneratorDriver.Generated", global::System.UriKind.Relative), 8, 9);
var label = new global::Microsoft.Maui.Controls.Label();
global::Microsoft.Maui.VisualDiagnostics.RegisterSourceInfo(label!, new global::System.Uri(@"Test.xaml;assembly=SourceGeneratorDriver.Generated", global::System.UriKind.Relative), 8, 3);
var __root = this;
global::Microsoft.Maui.VisualDiagnostics.RegisterSourceInfo(__root!, new global::System.Uri(@"Test.xaml;assembly=SourceGeneratorDriver.Generated", global::System.UriKind.Relative), 2, 2);
#if !_MAUIXAML_SG_NAMESCOPE_DISABLE
global::Microsoft.Maui.Controls.Internals.INameScope iNameScope = global::Microsoft.Maui.Controls.Internals.NameScope.GetNameScope(__root) ?? new global::Microsoft.Maui.Controls.Internals.NameScope();
#endif
#if !_MAUIXAML_SG_NAMESCOPE_DISABLE
global::Microsoft.Maui.Controls.Internals.NameScope.SetNameScope(__root, iNameScope);
#endif
#if !_MAUIXAML_SG_NAMESCOPE_DISABLE
label.transientNamescope = iNameScope;
#endif
#line 8 "{{testXamlFilePath}}"
bindingExtension.TargetNullValue = "0";
#line default
#line 8 "{{testXamlFilePath}}"
bindingExtension.Path = "CurrentPerson.Id";
#line default
var bindingBase = CreateTypedBindingFrom_bindingExtension(bindingExtension);
if (global::Microsoft.Maui.VisualDiagnostics.GetSourceInfo(bindingBase!) == null)
global::Microsoft.Maui.VisualDiagnostics.RegisterSourceInfo(bindingBase!, new global::System.Uri(@"Test.xaml;assembly=SourceGeneratorDriver.Generated", global::System.UriKind.Relative), 8, 9);
label.SetBinding(global::Microsoft.Maui.Controls.Label.TextProperty, bindingBase);
#line 8 "{{testXamlFilePath}}"
__root.SetValue(global::Microsoft.Maui.Controls.ContentPage.ContentProperty, label);
#line default
static global::Microsoft.Maui.Controls.BindingBase CreateTypedBindingFrom_bindingExtension(global::Microsoft.Maui.Controls.Xaml.BindingExtension extension)
{
global::System.Action<global::Test.TestPage, int>? setter = static (source, value) =>
{
if (source.CurrentPerson is {} p0)
{
p0.Id = value;
}
};

return new global::Microsoft.Maui.Controls.Internals.TypedBinding<global::Test.TestPage, int>(
getter: source => (source.CurrentPerson?.Id ?? extension.TargetNullValue as int? ?? default, true),
setter,
handlers: new global::System.Tuple<global::System.Func<global::Test.TestPage, object?>, string>[]
{
new(static source => source, "CurrentPerson"),
new(static source => source.CurrentPerson, "Id"),
})
{
TargetNullValue = extension.TargetNullValue,
};
}


}
}

""";

var (result, generated) = RunGenerator(xaml, code);

// Verify the generated code matches expected structure
CodeIsEqual(expected, generated ?? string.Empty);
}

[Theory]
[InlineData("{Binding .}")]
[InlineData("{Binding}")]
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2 changes: 1 addition & 1 deletion src/Controls/tests/SourceGen.UnitTests/InitializeComponent/LineInfoTests.cs
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Expand Up @@ -58,6 +58,6 @@ public void LineInfoDisabledDefault()

var generatedCode = result.GeneratedTrees.Single(tree => Path.GetFileName(tree.FilePath) == "Test.xaml.xsg.cs").ToString();
var expectedFilePath = Path.Combine(Environment.CurrentDirectory, "Test.xaml");
Assert.False(generatedCode.Contains(@$"#line 9 ""{expectedFilePath}""", StringComparison.Ordinal));
Assert.False(generatedCode.Contains(@$"#line 9 ""{expectedFilePath}""", StringComparison.Ordinal));
}
}
4 changes: 2 additions & 2 deletions ...ls/tests/SourceGen.UnitTests/InitializeComponent/SourceGenXamlInitializeComponentTests.cs
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Expand Up @@ -16,13 +16,13 @@ public class SourceGenXamlInitializeComponentTestBase : SourceGenTestsBase
protected record AdditionalXamlFile(string Path, string Content, string? RelativePath = null, string? TargetPath = null, string? ManifestResourceName = null, string? TargetFramework = null, string? NoWarn = null, string Lineinfo = "enable")
: AdditionalFile(Text: ToAdditionalText(Path, Content), Kind: "Xaml", RelativePath: RelativePath ?? Path, TargetPath: TargetPath, ManifestResourceName: ManifestResourceName, TargetFramework: TargetFramework, NoWarn: NoWarn, LineInfo: Lineinfo);

protected (GeneratorDriverRunResult result, string? text) RunGenerator(string xaml, string code, string noWarn = "", string targetFramework = "", string? path = null, string lineinfo = "enable")
protected (GeneratorDriverRunResult result, string? text) RunGenerator(string xaml, string code, string noWarn = "", string targetFramework = "", string? path = null, string lineinfo = "enable", bool assertNoCompilationErrors = true)
{
var compilation = CreateMauiCompilation();
compilation = compilation.AddSyntaxTrees(CSharpSyntaxTree.ParseText(code));
var workingDirectory = Environment.CurrentDirectory;
var xamlFile = new AdditionalXamlFile(Path.Combine(workingDirectory, path ?? "Test.xaml"), xaml, RelativePath: path ?? "Test.xaml", TargetFramework: targetFramework, NoWarn: noWarn, ManifestResourceName: $"{compilation.AssemblyName}.Test.xaml", Lineinfo: lineinfo);
var result = RunGenerator<XamlGenerator>(compilation, xamlFile);
var result = RunGenerator<XamlGenerator>(compilation, xamlFile, assertNoCompilationErrors);
var generated = result.Results.SingleOrDefault().GeneratedSources.SingleOrDefault(gs => gs.HintName.EndsWith(".xsg.cs")).SourceText?.ToString();

return (result, generated);
Expand Down
2 changes: 1 addition & 1 deletion src/Controls/tests/SourceGen.UnitTests/InitializeComponent/UnresolvedType.cs
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Expand Up @@ -130,7 +130,7 @@ private partial void InitializeComponent()

""";

var (result, generated) = RunGenerator(xaml, code);
var (result, generated) = RunGenerator(xaml, code, assertNoCompilationErrors: false);
Assert.False(result.Diagnostics.Any());
Assert.Equal(expected, generated, ignoreLineEndingDifferences: true);
}
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63 changes: 45 additions & 18 deletions src/Controls/tests/SourceGen.UnitTests/InitializeComponent/XStaticUnresolvedType.cs
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Expand Up @@ -27,14 +27,23 @@ public void XStaticWithClrNamespace()
using Microsoft.Maui.Controls;
using Microsoft.Maui.Controls.Xaml;

namespace Test;
namespace Test
{
[XamlProcessing(XamlInflator.SourceGen)]
partial class TestPage : ContentPage
{
public TestPage()
{
InitializeComponent();
}
}
}

[XamlProcessing(XamlInflator.SourceGen)]
partial class TestPage : ContentPage
namespace MyApp.Routes
{
public TestPage()
public static class Route
{
InitializeComponent();
public static string Value => "TestRoute";
}
}
""";
Expand Down Expand Up @@ -110,7 +119,7 @@ private partial void InitializeComponent()

""";

var (result, generated) = RunGenerator(xaml, code);
var (result, generated) = RunGenerator(xaml, code, assertNoCompilationErrors: true);
Assert.False(result.Diagnostics.Any());
Assert.Equal(expected, generated, ignoreLineEndingDifferences: true);
}
Expand All @@ -135,14 +144,23 @@ public void XStaticWithClrNamespaceAndAssembly()
using Microsoft.Maui.Controls;
using Microsoft.Maui.Controls.Xaml;

namespace Test;
namespace Test
{
[XamlProcessing(XamlInflator.SourceGen)]
partial class TestPage : ContentPage
{
public TestPage()
{
InitializeComponent();
}
}
}

[XamlProcessing(XamlInflator.SourceGen)]
partial class TestPage : ContentPage
namespace ExternalLib.Constants
{
public TestPage()
public static class AppConstants
{
InitializeComponent();
public static string AppName => "TestApp";
}
}
""";
Expand Down Expand Up @@ -218,7 +236,7 @@ private partial void InitializeComponent()

""";

var (result, generated) = RunGenerator(xaml, code);
var (result, generated) = RunGenerator(xaml, code, assertNoCompilationErrors: true);
Assert.False(result.Diagnostics.Any());
Assert.Equal(expected, generated, ignoreLineEndingDifferences: true);
}
Expand All @@ -243,14 +261,23 @@ public void XStaticWithClrNamespaceFieldAccess()
using Microsoft.Maui.Controls;
using Microsoft.Maui.Controls.Xaml;

namespace Test;
namespace Test
{
[XamlProcessing(XamlInflator.SourceGen)]
partial class TestPage : ContentPage
{
public TestPage()
{
InitializeComponent();
}
}
}

[XamlProcessing(XamlInflator.SourceGen)]
partial class TestPage : ContentPage
namespace MyApp.Config
{
public TestPage()
public static class Settings
{
InitializeComponent();
public static double DefaultFontSize => 14.0;
}
}
""";
Expand Down Expand Up @@ -326,7 +353,7 @@ private partial void InitializeComponent()

""";

var (result, generated) = RunGenerator(xaml, code);
var (result, generated) = RunGenerator(xaml, code, assertNoCompilationErrors: true);
Assert.False(result.Diagnostics.Any());
Assert.Equal(expected, generated, ignoreLineEndingDifferences: true);
}
Expand Down
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