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Merge pull request #735 from CommunityToolkit/dev/field-targeted-observableproperty
Add analyzer for [field: ObservableProperty] uses from auto-properties
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‎src/CommunityToolkit.Mvvm.SourceGenerators/AnalyzerReleases.Shipped.md

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@@ -67,3 +67,11 @@ Rule ID | Category | Severity | Notes
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MVVMTK0037 | CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator | Error | See https://aka.ms/mvvmtoolkit/errors/mvvmtk0037
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MVVMTK0038 | CommunityToolkit.Mvvm.SourceGenerators.RelayCommandGenerator | Error | See https://aka.ms/mvvmtoolkit/errors/mvvmtk0038
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MVVMTK0039 | CommunityToolkit.Mvvm.SourceGenerators.RelayCommandGenerator | Warning | See https://aka.ms/mvvmtoolkit/errors/mvvmtk0039
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## Release 8.2.2
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### New Rules
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Rule ID | Category | Severity | Notes
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--------|----------|----------|-------
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MVVMTK0040 | CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator | Error | See https://aka.ms/mvvmtoolkit/errors/mvvmtk0040

‎src/CommunityToolkit.Mvvm.SourceGenerators/CommunityToolkit.Mvvm.SourceGenerators.projitems

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<Compile Include="$(MSBuildThisFileDirectory)ComponentModel\TransitiveMembersGenerator.Execute.cs" />
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<Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\AsyncVoidReturningRelayCommandMethodAnalyzer.cs" />
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<Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\InvalidClassLevelNotifyDataErrorInfoAttributeAnalyzer.cs" />
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<Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\AutoPropertyWithFieldTargetedObservablePropertyAttributeAnalyzer.cs" />
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<Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\InvalidClassLevelNotifyPropertyChangedRecipientsAttributeAnalyzer.cs" />
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<Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\ClassUsingAttributeInsteadOfInheritanceAnalyzer.cs" />
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<Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\FieldWithOrphanedDependentObservablePropertyAttributesAnalyzer.cs" />

‎src/CommunityToolkit.Mvvm.SourceGenerators/Diagnostics/Analyzers/AutoPropertyWithFieldTargetedObservablePropertyAttributeAnalyzer.cs

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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 System.Collections.Immutable;
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using CommunityToolkit.Mvvm.SourceGenerators.Extensions;
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using Microsoft.CodeAnalysis;
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using Microsoft.CodeAnalysis.Diagnostics;
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using static CommunityToolkit.Mvvm.SourceGenerators.Diagnostics.DiagnosticDescriptors;
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namespace CommunityToolkit.Mvvm.SourceGenerators;
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/// <summary>
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/// A diagnostic analyzer that generates an error when an auto-property is using <c>[field: ObservableProperty]</c>.
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/// </summary>
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[DiagnosticAnalyzer(LanguageNames.CSharp)]
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public sealed class AutoPropertyWithFieldTargetedObservablePropertyAttributeAnalyzer : DiagnosticAnalyzer
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{
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/// <inheritdoc/>
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public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get; } = ImmutableArray.Create(AutoPropertyBackingFieldObservableProperty);
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/// <inheritdoc/>
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public override void Initialize(AnalysisContext context)
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{
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context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.Analyze | GeneratedCodeAnalysisFlags.ReportDiagnostics);
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context.EnableConcurrentExecution();
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context.RegisterCompilationStartAction(static context =>
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{
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// Get the symbol for [ObservableProperty]
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if (context.Compilation.GetTypeByMetadataName("CommunityToolkit.Mvvm.ComponentModel.ObservablePropertyAttribute") is not INamedTypeSymbol observablePropertySymbol)
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{
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return;
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}
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context.RegisterSymbolAction(context =>
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{
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// Get the property symbol and the type symbol for the containing type
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if (context.Symbol is not IPropertySymbol { ContainingType: INamedTypeSymbol typeSymbol } propertySymbol)
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{
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return;
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}
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foreach (ISymbol memberSymbol in typeSymbol.GetMembers())
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{
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// We're only looking for fields with an associated property
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if (memberSymbol is not IFieldSymbol { AssociatedSymbol: IPropertySymbol associatedPropertySymbol })
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{
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continue;
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}
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// Check that this field is in fact the backing field for the target auto-property
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if (!SymbolEqualityComparer.Default.Equals(associatedPropertySymbol, propertySymbol))
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{
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continue;
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}
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// If the field isn't using [ObservableProperty], this analyzer isn't applicable
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if (!memberSymbol.TryGetAttributeWithType(observablePropertySymbol, out AttributeData? attributeData))
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{
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return;
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}
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// Report the diagnostic on the attribute location
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context.ReportDiagnostic(Diagnostic.Create(
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AutoPropertyBackingFieldObservableProperty,
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attributeData.GetLocation(),
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typeSymbol,
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propertySymbol));
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}
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}, SymbolKind.Property);
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});
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}
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}

‎src/CommunityToolkit.Mvvm.SourceGenerators/Diagnostics/DiagnosticDescriptors.cs

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isEnabledByDefault: true,
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description: "All asynchronous methods annotated with [RelayCommand] should return a Task type, to benefit from the additional support provided by AsyncRelayCommand and AsyncRelayCommand<T>.",
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helpLinkUri: "https://aka.ms/mvvmtoolkit/errors/mvvmtk0039");
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/// <summary>
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/// Gets a <see cref="DiagnosticDescriptor"/> indicating when <c>[ObservableProperty]</c> is used on a generated field of an auto-property.
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/// <para>
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/// Format: <c>"The backing field for property {0}.{1} cannot be annotated with [ObservableProperty] (the attribute can only be used directly on fields, and the generator will then handle generating the corresponding property)"</c>.
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/// </para>
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/// </summary>
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public static readonly DiagnosticDescriptor AutoPropertyBackingFieldObservableProperty = new DiagnosticDescriptor(
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id: "MVVMTK0040",
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title: "[ObservableProperty] on auto-property backing field",
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messageFormat: "The backing field for property {0}.{1} cannot be annotated with [ObservableProperty] (the attribute can only be used directly on fields, and the generator will then handle generating the corresponding property)",
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category: typeof(ObservablePropertyGenerator).FullName,
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defaultSeverity: DiagnosticSeverity.Error,
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isEnabledByDefault: true,
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description: "The backing fields of auto-properties cannot be annotated with [ObservableProperty] (the attribute can only be used directly on fields, and the generator will then handle generating the corresponding property).",
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helpLinkUri: "https://aka.ms/mvvmtoolkit/errors/mvvmtk0040");
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}

‎src/CommunityToolkit.Mvvm.SourceGenerators/Extensions/AttributeDataExtensions.cs

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return false;
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}
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/// <summary>
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/// Tries to get the location of the input <see cref="AttributeData"/> instance.
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/// </summary>
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/// <param name="attributeData">The input <see cref="AttributeData"/> instance to get the location for.</param>
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/// <returns>The resulting location for <paramref name="attributeData"/>, if a syntax reference is available.</returns>
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public static Location? GetLocation(this AttributeData attributeData)
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{
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if (attributeData.ApplicationSyntaxReference is { } syntaxReference)
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{
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return syntaxReference.SyntaxTree.GetLocation(syntaxReference.Span);
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}
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return null;
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}
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/// <summary>
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/// Gets a given named argument value from an <see cref="AttributeData"/> instance, or a fallback value.
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/// </summary>

‎src/CommunityToolkit.Mvvm.SourceGenerators/Extensions/ISymbolExtensions.cs

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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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#if !ROSLYN_4_3_1_OR_GREATER
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using System.Diagnostics.CodeAnalysis;
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#endif
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using Microsoft.CodeAnalysis;
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namespace CommunityToolkit.Mvvm.SourceGenerators.Extensions;
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}
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/// <summary>
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/// Checks whether or not a given symbol has an attribute with the specified fully qualified metadata name.
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/// Checks whether or not a given symbol has an attribute with the specified type.
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/// </summary>
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/// <param name="symbol">The input <see cref="ISymbol"/> instance to check.</param>
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/// <param name="typeSymbol">The <see cref="ITypeSymbol"/> instance for the attribute type to look for.</param>
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/// <returns>Whether or not <paramref name="symbol"/> has an attribute with the specified type.</returns>
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public static bool HasAttributeWithType(this ISymbol symbol, ITypeSymbol typeSymbol)
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{
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return TryGetAttributeWithType(symbol, typeSymbol, out _);
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}
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/// <summary>
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/// Tries to get an attribute with the specified type.
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/// </summary>
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/// <param name="symbol">The input <see cref="ISymbol"/> instance to check.</param>
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/// <param name="typeSymbol">The <see cref="ITypeSymbol"/> instance for the attribute type to look for.</param>
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/// <param name="attributeData">The resulting attribute, if it was found.</param>
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/// <returns>Whether or not <paramref name="symbol"/> has an attribute with the specified type.</returns>
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public static bool TryGetAttributeWithType(this ISymbol symbol, ITypeSymbol typeSymbol, [NotNullWhen(true)] out AttributeData? attributeData)
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{
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foreach (AttributeData attribute in symbol.GetAttributes())
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{
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if (SymbolEqualityComparer.Default.Equals(attribute.AttributeClass, typeSymbol))
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{
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attributeData = attribute;
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return true;
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}
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}
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attributeData = null;
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return false;
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}
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‎tests/CommunityToolkit.Mvvm.SourceGenerators.UnitTests/Test_SourceGeneratorsDiagnostics.cs

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await VerifyAnalyzerDiagnosticsAndSuccessfulGeneration<AsyncVoidReturningRelayCommandMethodAnalyzer>(source, LanguageVersion.CSharp8);
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}
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[TestMethod]
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public async Task FieldTargetedObservablePropertyAttribute_InstanceAutoProperty()
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{
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string source = """
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using CommunityToolkit.Mvvm.ComponentModel;
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namespace MyApp
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{
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public partial class SampleViewModel : ObservableObject
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{
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[field: {|MVVMTK0040:ObservableProperty|}]
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public string Name { get; set; }
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}
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}
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""";
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await VerifyAnalyzerDiagnosticsAndSuccessfulGeneration<AutoPropertyWithFieldTargetedObservablePropertyAttributeAnalyzer>(source, LanguageVersion.CSharp8);
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}
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[TestMethod]
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public async Task FieldTargetedObservablePropertyAttribute_StaticAutoProperty()
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{
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string source = """
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using CommunityToolkit.Mvvm.ComponentModel;
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namespace MyApp
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{
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public partial class SampleViewModel : ObservableObject
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{
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[field: {|MVVMTK0040:ObservableProperty|}]
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public static string Name { get; set; }
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}
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}
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""";
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await VerifyAnalyzerDiagnosticsAndSuccessfulGeneration<AutoPropertyWithFieldTargetedObservablePropertyAttributeAnalyzer>(source, LanguageVersion.CSharp8);
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}
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[TestMethod]
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public async Task FieldTargetedObservablePropertyAttribute_RecordPrimaryConstructorParameter()
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{
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string source = """
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using CommunityToolkit.Mvvm.ComponentModel;
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namespace MyApp
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{
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public partial record SampleViewModel([field: {|MVVMTK0040:ObservableProperty|}] string Name);
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}
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namespace System.Runtime.CompilerServices
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{
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internal static class IsExternalInit
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{
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}
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}
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""";
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await VerifyAnalyzerDiagnosticsAndSuccessfulGeneration<AutoPropertyWithFieldTargetedObservablePropertyAttributeAnalyzer>(source, LanguageVersion.CSharp9);
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}
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/// <summary>
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/// Verifies the diagnostic errors for a given analyzer, and that all available source generators can run successfully with the input source (including subsequent compilation).
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/// </summary>

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