Allow forwarding attributes to property accessors

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

@@ -48,7 +48,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\FieldReferenceForObservablePropertyFieldAnalyzer.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\UnsupportedCSharpLanguageVersionAnalyzer.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Suppressors\RelayCommandAttributeWithFieldOrPropertyTargetDiagnosticSuppressor.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Suppressors\ObservablePropertyAttributeWithPropertyTargetDiagnosticSuppressor.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Suppressors\ObservablePropertyAttributeWithSupportedTargetDiagnosticSuppressor.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\DiagnosticDescriptors.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\SuppressionDescriptors.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Extensions\AttributeDataExtensions.cs" />

src/CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/Models/AttributeInfo.cs

@@ -9,6 +9,7 @@
 using CommunityToolkit.Mvvm.SourceGenerators.Extensions;
 using CommunityToolkit.Mvvm.SourceGenerators.Helpers;
 using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using static Microsoft.CodeAnalysis.CSharp.SyntaxFactory;
 
@@ -17,10 +18,12 @@ namespace CommunityToolkit.Mvvm.SourceGenerators.ComponentModel.Models;
 /// <summary>
 /// A model representing an attribute declaration.
 /// </summary>
+/// <param name="AttributeTarget">Indicates the target of the attribute.</param>
 /// <param name="TypeName">The type name of the attribute.</param>
 /// <param name="ConstructorArgumentInfo">The <see cref="TypedConstantInfo"/> values for all constructor arguments for the attribute.</param>
 /// <param name="NamedArgumentInfo">The <see cref="TypedConstantInfo"/> values for all named arguments for the attribute.</param>
 internal sealed record AttributeInfo(
+    SyntaxKind AttributeTarget,
     string TypeName,
     EquatableArray<TypedConstantInfo> ConstructorArgumentInfo,
     EquatableArray<(string Name, TypedConstantInfo Value)> NamedArgumentInfo)
@@ -50,6 +53,7 @@ public static AttributeInfo Create(AttributeData attributeData)
         }
 
         return new(
+            SyntaxKind.PropertyKeyword,
             typeName,
             constructorArguments.ToImmutable(),
             namedArguments.ToImmutable());
@@ -61,13 +65,15 @@ public static AttributeInfo Create(AttributeData attributeData)
     /// <param name="typeSymbol">The symbol for the attribute type.</param>
     /// <param name="semanticModel">The <see cref="SemanticModel"/> instance for the current run.</param>
     /// <param name="arguments">The sequence of <see cref="AttributeArgumentSyntax"/> instances to process.</param>
+    /// <param name="syntaxKind">The kind of target for the attribute.</param>
     /// <param name="token">The cancellation token for the current operation.</param>
     /// <param name="info">The resulting <see cref="AttributeInfo"/> instance, if available</param>
     /// <returns>Whether a resulting <see cref="AttributeInfo"/> instance could be created.</returns>
     public static bool TryCreate(
         INamedTypeSymbol typeSymbol,
         SemanticModel semanticModel,
         IEnumerable<AttributeArgumentSyntax> arguments,
+        SyntaxKind syntaxKind,
         CancellationToken token,
         [NotNullWhen(true)] out AttributeInfo? info)
     {
@@ -105,6 +111,7 @@ public static bool TryCreate(
         }
 
         info = new AttributeInfo(
+            syntaxKind,
             typeName,
             constructorArguments.ToImmutable(),
             namedArguments.ToImmutable());

src/CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/ObservablePropertyGenerator.Execute.cs

@@ -216,10 +216,10 @@ public static bool TryGetInfo(
             // Gather explicit forwarded attributes info
             foreach (AttributeListSyntax attributeList in fieldSyntax.AttributeLists)
             {
-                // Only look for attribute lists explicitly targeting the (generated) property. Roslyn will normally emit a
-                // CS0657 warning (invalid target), but that is automatically suppressed by a dedicated diagnostic suppressor
-                // that recognizes uses of this target specifically to support [ObservableProperty].
-                if (attributeList.Target?.Identifier is not SyntaxToken(SyntaxKind.PropertyKeyword))
+                // Only look for attribute lists explicitly targeting the (generated) property or one of its accessors. Roslyn will
+                // normally emit a CS0657 warning (invalid target), but that is automatically suppressed by a dedicated diagnostic
+                // suppressor that recognizes uses of this target specifically to support [ObservableProperty].
+                if (attributeList.Target?.Identifier is not SyntaxToken(SyntaxKind.PropertyKeyword or SyntaxKind.GetKeyword or SyntaxKind.SetKeyword) targetIdentifier)
                 {
                     continue;
                 }
@@ -256,7 +256,7 @@ public static bool TryGetInfo(
                     IEnumerable<AttributeArgumentSyntax> attributeArguments = attribute.ArgumentList?.Arguments ?? Enumerable.Empty<AttributeArgumentSyntax>();
 
                     // Try to extract the forwarded attribute
-                    if (!AttributeInfo.TryCreate(attributeTypeSymbol, semanticModel, attributeArguments, token, out AttributeInfo? attributeInfo))
+                    if (!AttributeInfo.TryCreate(attributeTypeSymbol, semanticModel, attributeArguments, targetIdentifier.Kind(), token, out AttributeInfo? attributeInfo))
                     {
                         builder.Add(
                             InvalidPropertyTargetedAttributeExpressionOnObservablePropertyField,
@@ -1025,11 +1025,22 @@ public static MemberDeclarationSyntax GetPropertySyntax(PropertyInfo propertyInf
                             Argument(IdentifierName("value")))),
                     Block(setterStatements.AsEnumerable()));
 
-            // Prepare the forwarded attributes, if any
-            ImmutableArray<AttributeListSyntax> forwardedAttributes =
+            // Prepare the forwarded attributes, if any, for all targets
+            AttributeListSyntax[] forwardedPropertyAttributes =
                 propertyInfo.ForwardedAttributes
+                .Where(static a => a.AttributeTarget is SyntaxKind.PropertyKeyword)
                 .Select(static a => AttributeList(SingletonSeparatedList(a.GetSyntax())))
-                .ToImmutableArray();
+                .ToArray();
+            AttributeListSyntax[] forwardedGetAccessorAttributes =
+                propertyInfo.ForwardedAttributes
+                .Where(static a => a.AttributeTarget is SyntaxKind.GetKeyword)
+                .Select(static a => AttributeList(SingletonSeparatedList(a.GetSyntax())))
+                .ToArray();
+            AttributeListSyntax[] forwardedSetAccessorAttributes =
+                propertyInfo.ForwardedAttributes
+                .Where(static a => a.AttributeTarget is SyntaxKind.SetKeyword)
+                .Select(static a => AttributeList(SingletonSeparatedList(a.GetSyntax())))
+                .ToArray();
 
             // Prepare the setter for the generated property:
             //
@@ -1065,6 +1076,9 @@ public static MemberDeclarationSyntax GetPropertySyntax(PropertyInfo propertyInf
                             AttributeArgument(LiteralExpression(SyntaxKind.StringLiteralExpression, Literal("The type of the current instance cannot be statically discovered.")))))));
             }
 
+            // Also add any forwarded attributes
+            setAccessor = setAccessor.AddAttributeLists(forwardedSetAccessorAttributes);
+
             // Construct the generated property as follows:
             //
             // /// <inheritdoc cref="<FIELD_NAME>"/>
@@ -1073,6 +1087,7 @@ public static MemberDeclarationSyntax GetPropertySyntax(PropertyInfo propertyInf
             // <FORWARDED_ATTRIBUTES>
             // public <FIELD_TYPE><NULLABLE_ANNOTATION?> <PROPERTY_NAME>
             // {
+            //     <FORWARDED_ATTRIBUTES>
             //     get => <FIELD_NAME>;
             //     <SET_ACCESSOR>
             // }
@@ -1086,12 +1101,13 @@ public static MemberDeclarationSyntax GetPropertySyntax(PropertyInfo propertyInf
                             AttributeArgument(LiteralExpression(SyntaxKind.StringLiteralExpression, Literal(typeof(ObservablePropertyGenerator).Assembly.GetName().Version.ToString()))))))
                     .WithOpenBracketToken(Token(TriviaList(Comment($"/// <inheritdoc cref=\"{getterFieldIdentifierName}\"/>")), SyntaxKind.OpenBracketToken, TriviaList())),
                     AttributeList(SingletonSeparatedList(Attribute(IdentifierName("global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage")))))
-                .AddAttributeLists(forwardedAttributes.ToArray())
+                .AddAttributeLists(forwardedPropertyAttributes)
                 .AddModifiers(Token(SyntaxKind.PublicKeyword))
                 .AddAccessorListAccessors(
                     AccessorDeclaration(SyntaxKind.GetAccessorDeclaration)
                     .WithExpressionBody(ArrowExpressionClause(getterFieldExpression))
-                    .WithSemicolonToken(Token(SyntaxKind.SemicolonToken)),
+                    .WithSemicolonToken(Token(SyntaxKind.SemicolonToken))
+                    .AddAttributeLists(forwardedGetAccessorAttributes),
                     setAccessor);
         }
 

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

@@ -17,7 +17,15 @@ internal static class SuppressionDescriptors
     public 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");
+        justification: "Fields using [ObservableProperty] can use [property:], [set:] and [set:] attribute lists to forward attributes to the generated properties");
+
+    /// <summary>
+    /// Gets a <see cref="SuppressionDescriptor"/> for a field using [ObservableProperty] with an attribute list targeting a get or set accessor.
+    /// </summary>
+    public static readonly SuppressionDescriptor PropertyAttributeListForObservablePropertyFieldAccessors = new(
+        id: "MVVMTKSPR0001",
+        suppressedDiagnosticId: "CS0658",
+        justification: "Fields using [ObservableProperty] can use [property:], [set:] and [set:] attribute lists to forward attributes to the generated properties");
 
     /// <summary>
     /// Gets a <see cref="SuppressionDescriptor"/> for a method using [RelayCommand] with an attribute list targeting a field or property.

src/CommunityToolkit.Mvvm.SourceGenerators/Diagnostics/Suppressors/ObservablePropertyAttributeWithPropertyTargetDiagnosticSuppressor.cs → src/CommunityToolkit.Mvvm.SourceGenerators/Diagnostics/Suppressors/ObservablePropertyAttributeWithSupportedTargetDiagnosticSuppressor.cs

@@ -14,7 +14,7 @@ namespace CommunityToolkit.Mvvm.SourceGenerators;
 
 /// <summary>
 /// <para>
-/// A diagnostic suppressor to suppress CS0657 warnings for fields with [ObservableProperty] using a [property:] attribute list.
+/// A diagnostic suppressor to suppress CS0657 warnings for fields with [ObservableProperty] using a [property:] attribute list (or [set:] or [get:]).
 /// </para>
 /// <para>
 /// That is, this diagnostic suppressor will suppress the following diagnostic:
@@ -29,10 +29,10 @@ namespace CommunityToolkit.Mvvm.SourceGenerators;
 /// </para>
 /// </summary>
 [DiagnosticAnalyzer(LanguageNames.CSharp)]
-public sealed class ObservablePropertyAttributeWithPropertyTargetDiagnosticSuppressor : DiagnosticSuppressor
+public sealed class ObservablePropertyAttributeWithSupportedTargetDiagnosticSuppressor : DiagnosticSuppressor
 {
     /// <inheritdoc/>
-    public override ImmutableArray<SuppressionDescriptor> SupportedSuppressions => ImmutableArray.Create(PropertyAttributeListForObservablePropertyField);
+    public override ImmutableArray<SuppressionDescriptor> SupportedSuppressions => ImmutableArray.Create(PropertyAttributeListForObservablePropertyField, PropertyAttributeListForObservablePropertyFieldAccessors);
 
     /// <inheritdoc/>
     public override void ReportSuppressions(SuppressionAnalysisContext context)
@@ -43,7 +43,7 @@ public override void ReportSuppressions(SuppressionAnalysisContext context)
 
             // 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))
+                (attributeTarget.Identifier.IsKind(SyntaxKind.PropertyKeyword) || attributeTarget.Identifier.IsKind(SyntaxKind.GetKeyword) || attributeTarget.Identifier.IsKind(SyntaxKind.SetKeyword)))
             {
                 SemanticModel semanticModel = context.GetSemanticModel(syntaxNode.SyntaxTree);
 

src/CommunityToolkit.Mvvm.SourceGenerators/Input/Models/CommandInfo.cs

@@ -23,8 +23,7 @@ namespace CommunityToolkit.Mvvm.SourceGenerators.Input.Models;
 /// <param name="AllowConcurrentExecutions">Whether or not concurrent executions have been enabled.</param>
 /// <param name="FlowExceptionsToTaskScheduler">Whether or not exceptions should flow to the task scheduler.</param>
 /// <param name="IncludeCancelCommand">Whether or not to also generate a cancel command.</param>
-/// <param name="ForwardedFieldAttributes">The sequence of forwarded attributes for the generated field.</param>
-/// <param name="ForwardedPropertyAttributes">The sequence of forwarded attributes for the generated property.</param>
+/// <param name="ForwardedAttributes">The sequence of forwarded attributes for the generated members.</param>
 internal sealed record CommandInfo(
     string MethodName,
     string FieldName,
@@ -39,5 +38,4 @@ internal sealed record CommandInfo(
     bool AllowConcurrentExecutions,
     bool FlowExceptionsToTaskScheduler,
     bool IncludeCancelCommand,
-    EquatableArray<AttributeInfo> ForwardedFieldAttributes,
-    EquatableArray<AttributeInfo> ForwardedPropertyAttributes);
+    EquatableArray<AttributeInfo> ForwardedAttributes);