Fix member generation in sealed types

Author: Sergio0694

CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/INotifyPropertyChangedGenerator.cs

@@ -2,12 +2,14 @@
 // 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.Generic;
 using System.Collections.Immutable;
 using System.Linq;
 using CommunityToolkit.Mvvm.SourceGenerators.Diagnostics;
 using CommunityToolkit.Mvvm.SourceGenerators.Extensions;
 using CommunityToolkit.Mvvm.SourceGenerators.Input.Models;
 using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using static CommunityToolkit.Mvvm.SourceGenerators.Diagnostics.DiagnosticDescriptors;
 
@@ -30,12 +32,10 @@ public INotifyPropertyChangedGenerator()
     /// <inheritdoc/>
     protected override INotifyPropertyChangedInfo GetInfo(INamedTypeSymbol typeSymbol, AttributeData attributeData)
     {
-        if (attributeData.TryGetNamedArgument("IncludeAdditionalHelperMethods", out bool includeAdditionalHelperMethods))
-        {
-            return new(includeAdditionalHelperMethods);
-        }
+        bool includeAdditionalHelperMethods = attributeData.GetNamedArgument<bool>("IncludeAdditionalHelperMethods", true);
+        bool isSealed = typeSymbol.IsSealed;
 
-        return new(false);
+        return new(includeAdditionalHelperMethods, isSealed);
     }
 
     /// <inheritdoc/>
@@ -61,15 +61,26 @@ protected override bool ValidateTargetType(INamedTypeSymbol typeSymbol, INotifyP
     /// <inheritdoc/>
     protected override ImmutableArray<MemberDeclarationSyntax> FilterDeclaredMembers(INotifyPropertyChangedInfo info, ClassDeclarationSyntax classDeclaration)
     {
+        IEnumerable<MemberDeclarationSyntax> memberDeclarations;
+
         // If requested, only include the event and the basic methods to raise it, but not the additional helpers
-        if (!info.IncludeAdditionalHelperMethods)
+        if (info.IncludeAdditionalHelperMethods)
+        {
+            memberDeclarations = classDeclaration.Members;
+        }
+        else
         {
-            return classDeclaration.Members.Where(
-                static member => member
-                    is EventFieldDeclarationSyntax
-                    or MethodDeclarationSyntax { Identifier.ValueText: "OnPropertyChanged" }).ToImmutableArray();
+            memberDeclarations = classDeclaration.Members.Where(static member => member
+                is EventFieldDeclarationSyntax
+                or MethodDeclarationSyntax { Identifier.ValueText: "OnPropertyChanged" });
         }
 
-        return classDeclaration.Members.ToImmutableArray();
+        // If the target class is sealed, make protected members private and remove the virtual modifier
+        return
+            memberDeclarations
+            .Select(static member => member
+                .ReplaceModifier(SyntaxKind.ProtectedKeyword, SyntaxKind.PrivateKeyword)
+                .RemoveModifier(SyntaxKind.VirtualKeyword))
+            .ToImmutableArray();
     }
 }

CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/Models/INotifyPropertyChangedInfo.cs

@@ -8,4 +8,5 @@ namespace CommunityToolkit.Mvvm.SourceGenerators.Input.Models;
 /// A model with gathered info on a given <c>INotifyPropertyChangedAttribute</c> instance.
 /// </summary>
 /// <param name="IncludeAdditionalHelperMethods">Whether to also generate helper methods in the target type.</param>
-public sealed record INotifyPropertyChangedInfo(bool IncludeAdditionalHelperMethods);
+/// <param name="IsSealed">Whether the target type is sealed.</param>
+public sealed record INotifyPropertyChangedInfo(bool IncludeAdditionalHelperMethods, bool IsSealed);

CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/Models/ObservableRecipientInfo.cs

@@ -10,9 +10,11 @@ namespace CommunityToolkit.Mvvm.SourceGenerators.ComponentModel.Models;
 /// <param name="TypeName">The type name of the type being annotated.</param>
 /// <param name="HasExplicitConstructors">Whether or not the target type has explicit constructors.</param>
 /// <param name="IsAbstract">Whether or not the target type is abstract.</param>
+/// <param name="IsSealed">Whether the target type is sealed.</param>
 /// <param name="IsObservableValidator">Whether or not the target type inherits from <c>ObservableValidator</c>.</param>
 public sealed record ObservableRecipientInfo(
     string TypeName,
     bool HasExplicitConstructors,
     bool IsAbstract,
+    bool IsSealed,
     bool IsObservableValidator);

CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/ObservableObjectGenerator.cs

@@ -7,6 +7,7 @@
 using CommunityToolkit.Mvvm.SourceGenerators.Diagnostics;
 using CommunityToolkit.Mvvm.SourceGenerators.Extensions;
 using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using static CommunityToolkit.Mvvm.SourceGenerators.Diagnostics.DiagnosticDescriptors;
 
@@ -16,7 +17,7 @@ namespace CommunityToolkit.Mvvm.SourceGenerators;
 /// A source generator for the <c>ObservableObjectAttribute</c> type.
 /// </summary>
 [Generator(LanguageNames.CSharp)]
-public sealed class ObservableObjectGenerator : TransitiveMembersGenerator<object?>
+public sealed class ObservableObjectGenerator : TransitiveMembersGenerator<bool>
 {
     /// <summary>
     /// Initializes a new instance of the <see cref="ObservableObjectGenerator"/> class.
@@ -27,13 +28,13 @@ public ObservableObjectGenerator()
     }
 
     /// <inheritdoc/>
-    protected override object? GetInfo(INamedTypeSymbol typeSymbol, AttributeData attributeData)
+    protected override bool GetInfo(INamedTypeSymbol typeSymbol, AttributeData attributeData)
     {
-        return null;
+        return typeSymbol.IsSealed;
     }
 
     /// <inheritdoc/>
-    protected override bool ValidateTargetType(INamedTypeSymbol typeSymbol, object? info, out ImmutableArray<Diagnostic> diagnostics)
+    protected override bool ValidateTargetType(INamedTypeSymbol typeSymbol, bool info, out ImmutableArray<Diagnostic> diagnostics)
     {
         ImmutableArray<Diagnostic>.Builder builder = ImmutableArray.CreateBuilder<Diagnostic>();
 
@@ -63,8 +64,19 @@ protected override bool ValidateTargetType(INamedTypeSymbol typeSymbol, object?
     }
 
     /// <inheritdoc/>
-    protected override ImmutableArray<MemberDeclarationSyntax> FilterDeclaredMembers(object? info, ClassDeclarationSyntax classDeclaration)
+    protected override ImmutableArray<MemberDeclarationSyntax> FilterDeclaredMembers(bool info, ClassDeclarationSyntax classDeclaration)
     {
+        // If the target class is sealed, make protected members private and remove the virtual modifier
+        if (info)
+        {
+            return
+                classDeclaration.Members
+                .Select(static member => member
+                    .ReplaceModifier(SyntaxKind.ProtectedKeyword, SyntaxKind.PrivateKeyword)
+                    .RemoveModifier(SyntaxKind.VirtualKeyword))
+                .ToImmutableArray();
+        }
+
         return classDeclaration.Members.ToImmutableArray();
     }
 }

CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/ObservableRecipientGenerator.cs

@@ -35,12 +35,14 @@ protected override ObservableRecipientInfo GetInfo(INamedTypeSymbol typeSymbol,
         string typeName = typeSymbol.Name;
         bool hasExplicitConstructors = !(typeSymbol.InstanceConstructors.Length == 1 && typeSymbol.InstanceConstructors[0] is { Parameters.IsEmpty: true, IsImplicitlyDeclared: true });
         bool isAbstract = typeSymbol.IsAbstract;
+        bool isSealed = typeSymbol.IsSealed;
         bool isObservableValidator = typeSymbol.InheritsFrom("global::CommunityToolkit.Mvvm.ComponentModel.ObservableValidator");
 
         return new(
             typeName,
             hasExplicitConstructors,
             isAbstract,
+            isSealed,
             isObservableValidator);
     }
 
@@ -123,6 +125,17 @@ protected override ImmutableArray<MemberDeclarationSyntax> FilterDeclaredMembers
             builder.Add(member);
         }
 
+        // If the target class is sealed, make protected members private and remove the virtual modifier
+        if (info.IsSealed)
+        {
+            return
+                builder
+                .Select(static member => member
+                    .ReplaceModifier(SyntaxKind.ProtectedKeyword, SyntaxKind.PrivateKeyword)
+                    .RemoveModifier(SyntaxKind.VirtualKeyword))
+                .ToImmutableArray();
+        }
+
         return builder.ToImmutable();
     }
 }

CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/TransitiveMembersGenerator.cs

@@ -23,7 +23,6 @@ namespace CommunityToolkit.Mvvm.SourceGenerators;
 /// </summary>
 /// <typeparam name="TInfo">The type of info gathered for each target type to process.</typeparam>
 public abstract partial class TransitiveMembersGenerator<TInfo> : IIncrementalGenerator
-    where TInfo : class?
 {
     /// <summary>
     /// The fully qualified name of the attribute type to look for.

CommunityToolkit.Mvvm.SourceGenerators/Extensions/AttributeDataExtensions.cs

@@ -43,6 +43,24 @@ properties.Value.Value is T argumentValue &&
         return false;
     }
 
+    /// <summary>
+    /// Gets a given named argument value from an <see cref="AttributeData"/> instance, or a fallback value.
+    /// </summary>
+    /// <typeparam name="T">The type of argument to check.</typeparam>
+    /// <param name="attributeData">The target <see cref="AttributeData"/> instance to check.</param>
+    /// <param name="name">The name of the argument to check.</param>
+    /// <param name="fallback">The fallback value to use if the named argument is not present.</param>
+    /// <returns>The argument named <paramref name="name"/>, or a fallback value.</returns>
+    public static T? GetNamedArgument<T>(this AttributeData attributeData, string name, T? fallback = default)
+    {
+        if (attributeData.TryGetNamedArgument(name, out T? value))
+        {
+            return value;
+        }
+
+        return fallback;
+    }
+
     /// <summary>
     /// Tries to get a given named argument value from an <see cref="AttributeData"/> instance, if present.
     /// </summary>