Add new nullable diagnostics to analyzer

Author: Sergio0694

components/DependencyPropertyGenerator/CommunityToolkit.DependencyPropertyGenerator.SourceGenerators/AnalyzerReleases.Shipped.md

@@ -30,3 +30,5 @@ WCTDP0020 | CommunityToolkit.GeneratedDependencyPropertyDependencyPropertyGenera
 WCTDP0021 | CommunityToolkit.GeneratedDependencyPropertyDependencyPropertyGenerator | Warning |
 WCTDP0022 | CommunityToolkit.GeneratedDependencyPropertyDependencyPropertyGenerator | Warning |
 WCTDP0023 | CommunityToolkit.GeneratedDependencyPropertyDependencyPropertyGenerator | Error |
+WCTDP0024 | CommunityToolkit.GeneratedDependencyPropertyDependencyPropertyGenerator | Warning |
+WCTDP0025 | CommunityToolkit.GeneratedDependencyPropertyDependencyPropertyGenerator | Warning |

components/DependencyPropertyGenerator/CommunityToolkit.DependencyPropertyGenerator.SourceGenerators/Diagnostics/Analyzers/InvalidPropertyNullableAnnotationAnalyzer.cs

@@ -19,7 +19,12 @@ namespace CommunityToolkit.GeneratedDependencyProperty;
 public sealed class InvalidPropertyNullableAnnotationAnalyzer : DiagnosticAnalyzer
 {
     /// <inheritdoc/>
-    public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get; } = [NonNullablePropertyDeclarationIsNotEnforced];
+    public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get; } =
+    [
+        NonNullablePropertyDeclarationIsNotEnforced,
+        NotNullResilientAccessorsForNullablePropertyDeclaration,
+        NotNullResilientAccessorsForNullablePropertyDeclaration
+    ];
 
     /// <inheritdoc/>
     public override void Initialize(AnalysisContext context)
@@ -65,13 +70,14 @@ public override void Initialize(AnalysisContext context)
                     // If we have '[NotNull]', it means the property getter must always ensure that a non-null value is returned.
                     // This can be achieved in two different ways:
                     //   1) By implementing one of the 'On___Get' methods, and adding '[NotNull]' on the parameter.
-                    //   2) By having '[DisallowNull]' on the property, and either marking the property as required, or providing a non-null default value.
+                    //   2) By having '[DisallowNull]' on the property or implementing one of the 'On___Set' methods with '[NotNull]'
+                    //      on the parameter, and either marking the property as required, or providing a non-null default value.
                     if (!IsAccessorMethodMarkedAsNotNull(propertySymbol, SyntaxKind.GetAccessorDeclaration, notNullAttributeSymbols) &&
-                        !(propertySymbol.HasAttributeWithAnyType(disallowNullAttributeSymbols) &&
-                         (propertySymbol.IsRequired || IsDefaultValueNotNull(propertySymbol, attributeData, maybeNullAttributeSymbols, notNullAttributeSymbols))))
+                        !((propertySymbol.HasAttributeWithAnyType(disallowNullAttributeSymbols) || IsAccessorMethodMarkedAsNotNull(propertySymbol, SyntaxKind.SetAccessorDeclaration, notNullAttributeSymbols)) &&
+                          (propertySymbol.IsRequired || IsDefaultValueNotNull(propertySymbol, attributeData, maybeNullAttributeSymbols, notNullAttributeSymbols))))
                     {
                         context.ReportDiagnostic(Diagnostic.Create(
-                            NonNullablePropertyDeclarationIsNotEnforced,
+                            NotNullResilientAccessorsForNullablePropertyDeclaration,
                             attributeData.GetLocation(),
                             propertySymbol));
                     }
@@ -93,7 +99,7 @@ public override void Initialize(AnalysisContext context)
                             !IsAccessorMethodMarkedAsNotNull(propertySymbol, SyntaxKind.SetAccessorDeclaration, notNullAttributeSymbols))
                         {
                             context.ReportDiagnostic(Diagnostic.Create(
-                                NonNullablePropertyDeclarationIsNotEnforced,
+                                NotNullResilientAccessorsForNullablePropertyDeclaration,
                                 attributeData.GetLocation(),
                                 propertySymbol));
                         }

components/DependencyPropertyGenerator/CommunityToolkit.DependencyPropertyGenerator.SourceGenerators/Diagnostics/DiagnosticDescriptors.cs

@@ -324,4 +324,30 @@ internal static class DiagnosticDescriptors
         isEnabledByDefault: true,
         description: "Properties annotated with [GeneratedDependencyProperty] and setting 'PropertyType' must do so with a type that is compatible with the declared property type.",
         helpLinkUri: "https://aka.ms/toolkit/labs/windows");
+
+    /// <summary>
+    /// <c>The property '{0}' is not annotated as nullable and is using [AllowNull], but neither of its accessors are null-resilient (at least one generated 'On___Get' or 'On___Set' method must be implemented with [NotNull] on the 'propertyValue' parameter, to ensure assigning null values does not break the nullable annotations on the property)</c>.
+    /// </summary>
+    public static readonly DiagnosticDescriptor NotNullResilientAccessorsForNotNullablePropertyDeclaration = new(
+        id: "WCTDP0024",
+        title: "Non-nullable dependency property using [AllowNull] incorrectly",
+        messageFormat: "The property '{0}' is not annotated as nullable and is using [AllowNull], but neither of its accessors are null-resilient (at least one generated 'On___Get' or 'On___Set' method must be implemented with [NotNull] on the 'propertyValue' parameter, to ensure assigning null values does not break the nullable annotations on the property)",
+        category: typeof(DependencyPropertyGenerator).FullName,
+        defaultSeverity: DiagnosticSeverity.Warning,
+        isEnabledByDefault: true,
+        description: "Non-nullable properties annotated with [GeneratedDependencyProperty] using [AllowNull] should have at least one generated 'On___Get' or 'On___Set' method implemented as null-resilient (by adding [NotNull] on the 'propertyValue' parameter) to ensure assigning null values does not break the nullable annotations on the property.",
+        helpLinkUri: "https://aka.ms/toolkit/labs/windows");
+
+    /// <summary>
+    /// <c>The property '{0}' is annotated as nullable and is using [NotNull], but it's not guaranteeing that returned values will not be null (it must either make its 'get' accessor null-resilient, by implementing at least one generated 'On___Get' method with [NotNull] on the 'propertyValue' parameter, or it must either add [DisallowNull] or implement at least one generated 'On___Set' method with [NotNull], and also either mark the property as required, or ensure that its default value is not null)</c>.
+    /// </summary>
+    public static readonly DiagnosticDescriptor NotNullResilientAccessorsForNullablePropertyDeclaration = new(
+        id: "WCTDP0025",
+        title: "Nullable dependency property using [NotNull] incorrectly",
+        messageFormat: "The property '{0}' is annotated as nullable and is using [NotNull], but it's not guaranteeing that returned values will not be null (it must either make its 'get' accessor null-resilient, by implementing at least one generated 'On___Get' method with [NotNull] on the 'propertyValue' parameter, or it must either add [DisallowNull] or implement at least one generated 'On___Set' method with [NotNull], and also either mark the property as required, or ensure that its default value is not null)",
+        category: typeof(DependencyPropertyGenerator).FullName,
+        defaultSeverity: DiagnosticSeverity.Warning,
+        isEnabledByDefault: true,
+        description: "Nullable properties annotated with [GeneratedDependencyProperty] using [NotNull] should make their 'get' accessors null-resilient, by implementing at least one generated 'On___Get' method with [NotNull] on the 'propertyValue' parameter, or they must either add [DisallowNull] or implement at least one generated 'On___Set' method with [NotNull], and also either be marked as required properties, or ensure that the default value is not null.",
+        helpLinkUri: "https://aka.ms/toolkit/labs/windows");
 }