Add ObservablePropertyAttributeWithPropertyTargetDiagnosticSuppressor

Author: Sergio0694

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

@@ -52,6 +52,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)ComponentModel\TransitiveMembersGenerator.Execute.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\FieldWithOrphanedDependentObservablePropertyAttributesAnalyzer.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\UnsupportedCSharpLanguageVersionAnalyzer.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Suppressors\ObservablePropertyAttributeWithPropertyTargetDiagnosticSuppressor.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\DiagnosticDescriptors.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\DiagnosticExtensions.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Extensions\AttributeDataExtensions.cs" />

CommunityToolkit.Mvvm.SourceGenerators/Diagnostics/Suppressors/ObservablePropertyAttributeWithPropertyTargetDiagnosticSuppressor.cs

@@ -0,0 +1,70 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Immutable;
+using System.Linq;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Diagnostics;
+
+namespace CommunityToolkit.Mvvm.SourceGenerators;
+
+/// <summary>
+/// <para>
+/// A diagnostic suppressor to suppress CS0657 warnings for fields with [ObservableProperty] using a [property:] attribute list.
+/// </para>
+/// <para>
+/// That is, this diagnostic suppressor will suppress the following diagnostic:
+/// <code>
+/// public class MyViewModel : ObservableObject
+/// {
+///     [ObservableProperty]
+///     [property: JsonPropertyName("Name")]
+///     private string? name;
+/// }
+/// </code>
+/// </para>
+/// </summary>
+[DiagnosticAnalyzer(LanguageNames.CSharp)]
+public sealed class ObservablePropertyAttributeWithPropertyTargetDiagnosticSuppressor : DiagnosticSuppressor
+{
+    /// <summary>
+    /// Gets a <see cref="SuppressionDescriptor"/> for a field using [ObservableProperty] with on attribute list targeting a property.
+    /// </summary>
+    private static readonly SuppressionDescriptor PropertyAttributeListForObservablePropertyField = new(
+        id: "MVVMTKSPR0001",
+        suppressedDiagnosticId: "CS0657",
+        justification: "Fields using [ObservableProperty] can use [property:] attribute lists to forward attributes to the generated properties");
+
+    /// <inheritdoc/>
+    public override ImmutableArray<SuppressionDescriptor> SupportedSuppressions => ImmutableArray.Create(PropertyAttributeListForObservablePropertyField);
+
+    /// <inheritdoc/>
+    public override void ReportSuppressions(SuppressionAnalysisContext context)
+    {
+        foreach (Diagnostic diagnostic in context.ReportedDiagnostics)
+        {
+            SyntaxNode? syntaxNode = diagnostic.Location.SourceTree?.GetRoot(context.CancellationToken).FindNode(diagnostic.Location.SourceSpan);
+
+            // Check that the target is effectively [property:] over a field declaration with at least one variable, which is the only case we are interested in
+            if (syntaxNode is AttributeTargetSpecifierSyntax { Parent.Parent: FieldDeclarationSyntax { Declaration.Variables.Count: > 0 } fieldDeclaration } attributeTarget &&
+                attributeTarget.Identifier.IsKind(SyntaxKind.PropertyKeyword))
+            {
+                SemanticModel semanticModel = context.GetSemanticModel(syntaxNode.SyntaxTree);
+
+                // Get the field symbol from the first variable declaration
+                ISymbol? declaredSymbol = semanticModel.GetDeclaredSymbol(fieldDeclaration.Declaration.Variables[0], context.CancellationToken);
+
+                // Check if the field is using [ObservableProperty], in which case we should suppress the warning
+                if (declaredSymbol is IFieldSymbol fieldSymbol &&
+                    semanticModel.Compilation.GetTypeByMetadataName("CommunityToolkit.Mvvm.ComponentModel.ObservablePropertyAttribute") is INamedTypeSymbol observablePropertySymbol &&
+                    fieldSymbol.GetAttributes().Select(attribute => attribute.AttributeClass).Contains(observablePropertySymbol, SymbolEqualityComparer.Default))
+                {
+                    context.ReportSuppression(Suppression.Create(PropertyAttributeListForObservablePropertyField, diagnostic));
+                }
+            }
+        }
+    }
+}