Add 'InvalidPointerTypeObservablePropertyAttributeAnalyzer'

Author: Sergio0694

src/CommunityToolkit.Mvvm.SourceGenerators/AnalyzerReleases.Shipped.md

@@ -96,3 +96,4 @@ MVVMTK0051 | CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator
 MVVMTK0052 | CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator | Error | See https://aka.ms/mvvmtoolkit/errors/mvvmtk0052
 MVVMTK0053 | CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator | Error | See https://aka.ms/mvvmtoolkit/errors/mvvmtk0053
 MVVMTK0054 | CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator | Error | See https://aka.ms/mvvmtoolkit/errors/mvvmtk0054
+MVVMTK0055 | CommunityToolkit.Mvvm.SourceGenerators.ObservablePropertyGenerator | Error | See https://aka.ms/mvvmtoolkit/errors/mvvmtk0055

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

@@ -41,6 +41,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)ComponentModel\TransitiveMembersGenerator.Execute.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\AsyncVoidReturningRelayCommandMethodAnalyzer.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\InvalidGeneratedPropertyObservablePropertyAttributeAnalyzer.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\InvalidPointerTypeObservablePropertyAttributeAnalyzer.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\InvalidPartialPropertyLevelObservablePropertyAttributeAnalyzer.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\WinRTClassUsingNotifyPropertyChangedAttributesAnalyzer.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Diagnostics\Analyzers\WinRTGeneratedBindableCustomPropertyWithBasesMemberAnalyzer.cs" />

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

@@ -99,7 +99,7 @@ public static bool IsCandidateValidForCompilation(MemberDeclarationSyntax node,
         public static bool IsCandidateSymbolValid(ISymbol memberSymbol)
         {
 #if ROSLYN_4_12_0_OR_GREATER
-            // We only need additional checks for properties (Roslyn already validates things for fields in our scenarios)
+            // We only need these additional checks for properties (Roslyn already validates things for fields in our scenarios)
             if (memberSymbol is IPropertySymbol propertySymbol)
             {
                 // Ensure that the property declaration is a partial definition with no implementation
@@ -116,6 +116,14 @@ public static bool IsCandidateSymbolValid(ISymbol memberSymbol)
             }
 #endif
 
+            // Pointer types are never allowed in either case
+            if (memberSymbol is
+                IPropertySymbol { Type.TypeKind: TypeKind.Pointer or TypeKind.FunctionPointer } or
+                IFieldSymbol { Type.TypeKind: TypeKind.Pointer or TypeKind.FunctionPointer })
+            {
+                return false;
+            }
+
             // We assume all other cases are supported (other failure cases will be detected later)
             return true;
         }

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

@@ -0,0 +1,64 @@
+// 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 CommunityToolkit.Mvvm.SourceGenerators.Extensions;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Diagnostics;
+using static CommunityToolkit.Mvvm.SourceGenerators.Diagnostics.DiagnosticDescriptors;
+
+namespace CommunityToolkit.Mvvm.SourceGenerators;
+
+/// <summary>
+/// A diagnostic analyzer that generates an error whenever <c>[ObservableProperty]</c> is used with pointer types.
+/// </summary>
+[DiagnosticAnalyzer(LanguageNames.CSharp)]
+public sealed class InvalidPointerTypeObservablePropertyAttributeAnalyzer : DiagnosticAnalyzer
+{
+    /// <inheritdoc/>
+    public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get; } = ImmutableArray.Create(InvalidObservablePropertyDeclarationReturnsPointerLikeType);
+
+    /// <inheritdoc/>
+    public override void Initialize(AnalysisContext context)
+    {
+        context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
+        context.EnableConcurrentExecution();
+
+        context.RegisterCompilationStartAction(static context =>
+        {
+            // Get the [ObservableProperty] symbol
+            if (context.Compilation.GetTypeByMetadataName("CommunityToolkit.Mvvm.ComponentModel.ObservablePropertyAttribute") is not INamedTypeSymbol observablePropertySymbol)
+            {
+                return;
+            }
+
+            context.RegisterSymbolAction(context =>
+            {
+                // Ensure that we have a valid target symbol to analyze
+                if (context.Symbol is not (IFieldSymbol or IPropertySymbol))
+                {
+                    return;
+                }
+
+                // If the property is not using [ObservableProperty], there's nothing to do
+                if (!context.Symbol.TryGetAttributeWithType(observablePropertySymbol, out AttributeData? observablePropertyAttribute))
+                {
+                    return;
+                }
+
+                // Emit a diagnostic if the type is a pointer type
+                if (context.Symbol is
+                    IPropertySymbol { Type.TypeKind: TypeKind.Pointer or TypeKind.FunctionPointer } or
+                    IFieldSymbol { Type.TypeKind: TypeKind.Pointer or TypeKind.FunctionPointer })
+                {
+                    context.ReportDiagnostic(Diagnostic.Create(
+                        InvalidObservablePropertyDeclarationReturnsPointerLikeType,
+                        observablePropertyAttribute.GetLocation(),
+                        context.Symbol.ContainingType,
+                        context.Symbol.Name));
+                }
+            }, SymbolKind.Field, SymbolKind.Property);
+        });
+    }
+}

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

@@ -907,4 +907,20 @@ internal static class DiagnosticDescriptors
         isEnabledByDefault: true,
         description: "A property using [ObservableProperty] returns a byref-like value ([ObservableProperty] must be used on properties of a non byref-like type).",
         helpLinkUri: "https://aka.ms/mvvmtoolkit/errors/mvvmtk0054");
+
+    /// <summary>
+    /// Gets a <see cref="DiagnosticDescriptor"/> for when <c>[ObservableProperty]</c> is used on a property that returns a pointer type.
+    /// <para>
+    /// Format: <c>"The property {0}.{1} returns a pointer or function pointer value ([ObservableProperty] must be used on properties of a non pointer-like type)"</c>.
+    /// </para>
+    /// </summary>
+    public static readonly DiagnosticDescriptor InvalidObservablePropertyDeclarationReturnsPointerLikeType = new DiagnosticDescriptor(
+        id: "MVVMTK0055",
+        title: "Using [ObservableProperty] on a property that returns pointer-like",
+        messageFormat: """The property {0}.{1} returns a pointer or function pointer value ([ObservableProperty] must be used on properties of a non pointer-like type)""",
+        category: typeof(ObservablePropertyGenerator).FullName,
+        defaultSeverity: DiagnosticSeverity.Error,
+        isEnabledByDefault: true,
+        description: "A property using [ObservableProperty] returns a pointer-like value ([ObservableProperty] must be used on properties of a non pointer-like type).",
+        helpLinkUri: "https://aka.ms/mvvmtoolkit/errors/mvvmtk0055");
 }