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Sergio0694Sergio0694
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Fix nullability checks in type parameter constraints
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3 files changed

+202
-1
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3 files changed

+202
-1
lines changed

‎components/DependencyPropertyGenerator/CommunityToolkit.DependencyPropertyGenerator.SourceGenerators/Extensions/ITypeParameterSymbolExtensions.cs‎

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@@ -0,0 +1,60 @@
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// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT license.
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// See the LICENSE file in the project root for more information.
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using Microsoft.CodeAnalysis;
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namespace CommunityToolkit.GeneratedDependencyProperty.Extensions;
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/// <summary>
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/// Extension methods for <see cref="ITypeParameterSymbol"/> types.
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/// </summary>
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internal static class ITypeParameterSymbolExtensions
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{
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/// <summary>
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/// Checks whether a given type parameter is a reference type.
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/// </summary>
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/// <param name="symbol">The input <see cref="ITypeParameterSymbol"/> instance to check.</param>
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/// <returns>Whether the input type parameter is a reference type.</returns>
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public static bool IsReferenceTypeOrIndirectlyConstrainedToReferenceType(this ITypeParameterSymbol symbol)
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{
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// The type is definitely a reference type (e.g. it has the 'class' constraint)
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if (symbol.IsReferenceType)
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{
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return true;
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}
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// The type is definitely a value type (e.g. it has the 'struct' constraint)
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if (symbol.IsValueType)
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{
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return false;
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}
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foreach (ITypeSymbol constraintType in symbol.ConstraintTypes)
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{
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// Recurse on the type parameter first (e. g. we might indirectly be getting a 'class' constraint)
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if (constraintType is ITypeParameterSymbol typeParameter &&
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typeParameter.IsReferenceTypeOrIndirectlyConstrainedToReferenceType())
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{
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return true;
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}
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// Special constraint type that type parameters can derive from. Note that for concrete enum
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// types, the 'Enum' constraint isn't sufficient, they'd also have e.g. 'struct', which is
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// already checked before. If a type parameter only has 'Enum', then it should be considered
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// a reference type.
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if (constraintType.SpecialType is SpecialType.System_Delegate or SpecialType.System_Enum)
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{
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return true;
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}
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// Only check for classes (an interface doesn't guarantee the type argument will be a reference type)
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if (constraintType.TypeKind is TypeKind.Class)
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{
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return true;
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}
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}
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return false;
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}
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}

‎components/DependencyPropertyGenerator/CommunityToolkit.DependencyPropertyGenerator.SourceGenerators/Extensions/ITypeSymbolExtensions.cs‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -25,7 +25,7 @@ public static bool IsDefaultValueNull(this ITypeSymbol symbol)
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// If we do have a type parameter, check that it does have some reference type constraint on it.
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if (symbol is ITypeParameterSymbol typeParameter)
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{
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return typeParameter.HasReferenceTypeConstraint;
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return typeParameter.IsReferenceTypeOrIndirectlyConstrainedToReferenceType();
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}
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return symbol is { IsValueType: false } or INamedTypeSymbol { IsGenericType: true, ConstructedFrom.SpecialType: SpecialType.System_Nullable_T };

‎components/DependencyPropertyGenerator/CommunityToolkit.DependencyPropertyGenerator.Tests/Test_Analyzers.cs‎

Lines changed: 141 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1765,6 +1765,68 @@ public partial class MyObject<T1, T2, T3, T4, T5> : DependencyObject
17651765
await CSharpAnalyzerTest<InvalidPropertyDefaultValueTypeAnalyzer>.VerifyAnalyzerAsync(source, LanguageVersion.CSharp13);
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}
17671767

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[TestMethod]
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[DataRow("where T : class", "null")]
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[DataRow("where T : class", "default(T)")]
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[DataRow("where T : TOther where TOther : class", "null")]
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[DataRow("where T : class where TOther : class", "default(TOther)")]
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[DataRow("where T : Delegate", "null")]
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[DataRow("where T : Enum", "null")]
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[DataRow("where T : DependencyObject", "null")]
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[DataRow("where T : DependencyObject", "default(T)")]
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[DataRow("where T : TOther where TOther : Delegate", "null")]
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[DataRow("where T : TOther where TOther : Enum", "null")]
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[DataRow("where T : TOther where TOther : DependencyObject", "null")]
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[DataRow("where T : DependencyObject where TOther : class", "default(TOther)")]
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public async Task InvalidPropertyDefaultValueTypeAnalyzer_TypeParameter_ConstrainedExplicitNull_DoesNotWarn(
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string typeConstraints,
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string defaultValue)
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{
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string source = $$"""
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using System;
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using CommunityToolkit.WinUI;
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using Windows.UI.Xaml;
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#nullable enable
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namespace MyApp;
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public partial class MyObject<T, TOther> : DependencyObject {{typeConstraints}}
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{
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[GeneratedDependencyProperty(DefaultValue = {{defaultValue}})]
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public partial T {|CS9248:Name|} { get; set; }
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}
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""";
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await CSharpAnalyzerTest<InvalidPropertyDefaultValueTypeAnalyzer>.VerifyAnalyzerAsync(source, LanguageVersion.CSharp13);
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}
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[TestMethod]
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[DataRow("where T : struct")]
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[DataRow("where T : unmanaged")]
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[DataRow("where T : struct, Enum")]
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[DataRow("where T : unmanaged, Enum")]
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public async Task InvalidPropertyDefaultValueTypeAnalyzer_TypeParameter_ConstrainedExplicitNull_Warns(string typeConstraints)
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{
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string source = $$"""
1812+
using System;
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using CommunityToolkit.WinUI;
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using Windows.UI.Xaml;
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1816+
#nullable enable
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1818+
namespace MyApp;
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public partial class MyObject<T, TOther> : DependencyObject {{typeConstraints}}
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{
1822+
[GeneratedDependencyProperty({|WCTDPG0010:DefaultValue = null|})]
1823+
public partial T {|CS9248:Name|} { get; set; }
1824+
}
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""";
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1827+
await CSharpAnalyzerTest<InvalidPropertyDefaultValueTypeAnalyzer>.VerifyAnalyzerAsync(source, LanguageVersion.CSharp13);
1828+
}
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17681830
[TestMethod]
17691831
[DataRow("string", "42")]
17701832
[DataRow("string", "3.14")]
@@ -3226,6 +3288,85 @@ public void Dispose()
32263288
await CSharpAnalyzerTest<UseGeneratedDependencyPropertyOnManualPropertyAnalyzer>.VerifyAnalyzerAsync(source, LanguageVersion.CSharp13);
32273289
}
32283290

3291+
// Regression test for a case found in the Microsoft Store
3292+
[TestMethod]
3293+
[DataRow("where T : class", "null")]
3294+
[DataRow("where T : class", "default(T)")]
3295+
[DataRow("where T : TOther where TOther : class", "null")]
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[DataRow("where T : class where TOther : class", "default(TOther)")]
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[DataRow("where T : Delegate", "null")]
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[DataRow("where T : Enum", "null")]
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[DataRow("where T : DependencyObject", "null")]
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[DataRow("where T : DependencyObject", "default(T)")]
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[DataRow("where T : TOther where TOther : Delegate", "null")]
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[DataRow("where T : TOther where TOther : Enum", "null")]
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[DataRow("where T : TOther where TOther : DependencyObject", "null")]
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[DataRow("where T : DependencyObject where TOther : class", "default(TOther)")]
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public async Task UseGeneratedDependencyPropertyOnManualPropertyAnalyzer_ValidProperty_WithNullConstrainedGeneric_Warns(
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string typeConstraints,
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string defaultValue)
3308+
{
3309+
string source = $$"""
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using System;
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using Windows.UI.Xaml;
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3313+
#nullable enable
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3315+
namespace MyApp;
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3317+
public partial class MyObject<T, TOther> : DependencyObject {{typeConstraints}}
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{
3319+
public static readonly DependencyProperty NameProperty = DependencyProperty.Register(
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name: "Name",
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propertyType: typeof(T),
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ownerType: typeof(MyObject<T, TOther>),
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typeMetadata: new PropertyMetadata({{defaultValue}}));
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3325+
public T {|WCTDPG0017:Name|}
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{
3327+
get => (T?)GetValue(NameProperty);
3328+
set => SetValue(NameProperty, value);
3329+
}
3330+
}
3331+
""";
3332+
3333+
await CSharpAnalyzerTest<UseGeneratedDependencyPropertyOnManualPropertyAnalyzer>.VerifyAnalyzerAsync(source, LanguageVersion.CSharp13);
3334+
}
3335+
3336+
[TestMethod]
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[DataRow("where T : struct")]
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[DataRow("where T : unmanaged")]
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[DataRow("where T : struct, Enum")]
3340+
[DataRow("where T : unmanaged, Enum")]
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public async Task UseGeneratedDependencyPropertyOnManualPropertyAnalyzer_ValidProperty_WithNullConstrainedGeneric_WCTDPG0031_DoesNotWarn(string typeConstraints)
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{
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string source = $$"""
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using System;
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using Windows.UI.Xaml;
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3347+
#nullable enable
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3349+
namespace MyApp;
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3351+
public partial class MyObject<T, TOther> : DependencyObject {{typeConstraints}}
3352+
{
3353+
public static readonly DependencyProperty NameProperty = DependencyProperty.Register(
3354+
name: "Name",
3355+
propertyType: typeof(T),
3356+
ownerType: typeof(MyObject<T, TOther>),
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typeMetadata: new PropertyMetadata({|WCTDPG0031:null|}));
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3359+
public T {|WCTDPG0017:Name|}
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{
3361+
get => (T)GetValue(NameProperty);
3362+
set => SetValue(NameProperty, value);
3363+
}
3364+
}
3365+
""";
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3367+
await CSharpAnalyzerTest<UseGeneratedDependencyPropertyOnManualPropertyAnalyzer>.VerifyAnalyzerAsync(source, LanguageVersion.CSharp13);
3368+
}
3369+
32293370
[TestMethod]
32303371
[DataRow("private static readonly")]
32313372
[DataRow("public static")]

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