Update generator for unconstrained generic nullability

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

@@ -18,7 +18,7 @@ namespace CommunityToolkit.Mvvm.SourceGenerators.ComponentModel.Models;
 /// <param name="NotifyPropertyChangedRecipients">Whether or not the generated property also broadcasts changes.</param>
 /// <param name="NotifyDataErrorInfo">Whether or not the generated property also validates its value.</param>
 /// <param name="IsOldPropertyValueDirectlyReferenced">Whether the old property value is being directly referenced.</param>
-/// <param name="IsReferenceType">Indicates whether the property is of a reference type.</param>
+/// <param name="IsReferenceTypeOrUnconstraindTypeParameter">Indicates whether the property is of a reference type or an unconstrained type parameter.</param>
 /// <param name="IncludeMemberNotNullOnSetAccessor">Indicates whether to include nullability annotations on the setter.</param>
 /// <param name="ForwardedAttributes">The sequence of forwarded attributes for the generated property.</param>
 internal sealed record PropertyInfo(
@@ -31,6 +31,6 @@ internal sealed record PropertyInfo(
  bool NotifyPropertyChangedRecipients,
  bool NotifyDataErrorInfo,
  bool IsOldPropertyValueDirectlyReferenced,
- bool IsReferenceType,
+ bool IsReferenceTypeOrUnconstraindTypeParameter,
  bool IncludeMemberNotNullOnSetAccessor,
  EquatableArray<AttributeInfo> ForwardedAttributes);

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

@@ -112,8 +112,13 @@ public static bool TryGetInfo(
  bool hasOrInheritsClassLevelNotifyDataErrorInfo = false;
  bool hasAnyValidationAttributes = false;
  bool isOldPropertyValueDirectlyReferenced = IsOldPropertyValueDirectlyReferenced(fieldSymbol, propertyName);
- bool isReferenceType = fieldSymbol.Type.IsReferenceType;
- bool includeMemberNotNullOnSetAccessor = GetIncludeMemberNotNullOnSetAccessor(fieldSymbol, semanticModel);
+
+ // Get the nullability info for the property
+ GetNullabilityInfo(
+ fieldSymbol,
+ semanticModel,
+ out bool isReferenceTypeOrUnconstraindTypeParameter,
+ out bool includeMemberNotNullOnSetAccessor);
 
  // Track the property changing event for the property, if the type supports it
  if (shouldInvokeOnPropertyChanging)
@@ -262,7 +267,7 @@ public static bool TryGetInfo(
  notifyRecipients,
  notifyDataErrorInfo,
  isOldPropertyValueDirectlyReferenced,
- isReferenceType,
+ isReferenceTypeOrUnconstraindTypeParameter,
  includeMemberNotNullOnSetAccessor,
  forwardedAttributes.ToImmutable());
 
@@ -671,13 +676,23 @@ private static bool IsOldPropertyValueDirectlyReferenced(IFieldSymbol fieldSymbo
  }
 
  /// <summary>
- /// Checks whether <see cref="MemberNotNullAttribute"/> should be used on the setter.
+ /// Gets the nullability info on the generated property
  /// </summary>
  /// <param name="fieldSymbol">The input <see cref="IFieldSymbol"/> instance to process.</param>
  /// <param name="semanticModel">The <see cref="SemanticModel"/> instance for the current run.</param>
- /// <returns>Whether <see cref="MemberNotNullAttribute"/> should be used on the setter.</returns>
- private static bool GetIncludeMemberNotNullOnSetAccessor(IFieldSymbol fieldSymbol, SemanticModel semanticModel)
+ /// <param name="isReferenceTypeOrUnconstraindTypeParameter">Whether the property type supports nullability.</param>
+ /// <param name="includeMemberNotNullOnSetAccessor">Whether <see cref="MemberNotNullAttribute"/> should be used on the setter.</param>
+ /// <returns></returns>
+ private static void GetNullabilityInfo(
+ IFieldSymbol fieldSymbol,
+ SemanticModel semanticModel,
+ out bool isReferenceTypeOrUnconstraindTypeParameter,
+ out bool includeMemberNotNullOnSetAccessor)
  {
+ // We're using IsValueType here and not IsReferenceType to also conver unconstrained type parameter cases.
+ // This will cover both reference types as well T when the constraints are not struct or unmanaged.
+ isReferenceTypeOrUnconstraindTypeParameter = !fieldSymbol.Type.IsValueType;
+
  // This is used to avoid nullability warnings when setting the property from a constructor, in case the field
  // was marked as not nullable. Nullability annotations are assumed to always be enabled to make the logic simpler.
  // Consider this example:
@@ -695,8 +710,8 @@ private static bool GetIncludeMemberNotNullOnSetAccessor(IFieldSymbol fieldSymbo
  //
  // The [MemberNotNull] attribute is needed on the setter for the generated Name property so that when Name
  // is set, the compiler can determine that the name backing field is also being set (to a non null value).
- return
- fieldSymbol.Type is { NullableAnnotation: not NullableAnnotation.Annotated, IsReferenceType: true } &&
+ includeMemberNotNullOnSetAccessor =
+ fieldSymbol.Type is { NullableAnnotation: not NullableAnnotation.Annotated, IsValueType: false } &&
  semanticModel.Compilation.HasAccessibleTypeWithMetadataName("System.Diagnostics.CodeAnalysis.MemberNotNullAttribute");
  }
 
@@ -1001,7 +1016,7 @@ public static ImmutableArray<MemberDeclarationSyntax> GetOnPropertyChangeMethods
  // happen when the property is first set to some value that is not null (but the backing field would still be so).
  // As a cheap way to check whether we need to add nullable, we can simply check whether the type name with nullability
  // annotations ends with a '?'. If it doesn't and the type is a reference type, we add it. Otherwise, we keep it.
- TypeSyntax oldValueTypeSyntax = propertyInfo.IsReferenceType switch
+ TypeSyntax oldValueTypeSyntax = propertyInfo.IsReferenceTypeOrUnconstraindTypeParameter switch
  {
  true when !propertyInfo.TypeNameWithNullabilityAnnotations.EndsWith("?")
  => IdentifierName($"{propertyInfo.TypeNameWithNullabilityAnnotations}?"),