Fix build error with generic ObservableValidator types

Author: Sergio0694

CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/ObservableValidatorValidateAllPropertiesGenerator.cs

@@ -28,7 +28,7 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
             .CreateSyntaxProvider(
                 static (node, _) => node is ClassDeclarationSyntax,
                 static (context, _) => (context.Node, Symbol: (INamedTypeSymbol)context.SemanticModel.GetDeclaredSymbol(context.Node)!))
-            .Where(static item => !item.Symbol.IsAbstract && item.Node.IsFirstSyntaxDeclarationForSymbol(item.Symbol))
+            .Where(static item => item.Symbol is { IsAbstract: false, IsGenericType: false } && item.Node.IsFirstSyntaxDeclarationForSymbol(item.Symbol))
             .Select(static (item, _) => item.Symbol);
 
         // Get the types that inherit from ObservableValidator and gather their info

CommunityToolkit.Mvvm/ComponentModel/ObservableValidator.cs

@@ -606,8 +606,8 @@ where getMethod is not null
                 from property in validatableProperties
                 select Expression.Call(inst0, validateMethod, new Expression[]
                 {
-                        Expression.Convert(Expression.Call(inst0, property.GetMethod), typeof(object)),
-                        Expression.Constant(property.Name)
+                    Expression.Convert(Expression.Call(inst0, property.GetMethod), typeof(object)),
+                    Expression.Constant(property.Name)
                 }));
 
             return Expression.Lambda<Action<object>>(body, arg0).Compile();

tests/CommunityToolkit.Mvvm.UnitTests/Test_ObservableValidator.cs

@@ -539,6 +539,32 @@ public void Test_ObservableRecipient_AbstractTypesDoNotTriggerCodeGeneration()
         Assert.IsNull(createAllPropertiesValidatorMethod);
     }
 
+    // See https://github.com/CommunityToolkit/dotnet/issues/246
+    [TestMethod]
+    public void Test_ObservableValidator_WithGenericTypeParameters()
+    {
+        GenericPerson<string> model = new();
+
+        model.Name = "Bob";
+
+        model.ValidateAllProperties();
+
+        Assert.IsTrue(model.HasErrors);
+
+        ValidationResult[] errors = model.GetErrors(nameof(model.Value)).ToArray();
+
+        Assert.IsNotNull(errors);
+        Assert.AreEqual(errors.Length, 1);
+
+        CollectionAssert.AreEqual(errors[0].MemberNames.ToArray(), new[] { nameof(model.Value) });
+
+        model.Value = "Ross";
+
+        model.ValidateAllProperties();
+
+        Assert.IsFalse(model.HasErrors);
+    }
+
     public class Person : ObservableValidator
     {
         private string? name;
@@ -797,4 +823,19 @@ public abstract class AbstractModelWithValidatableProperty : ObservableValidator
         [MinLength(2)]
         public string? Name { get; set; }
     }
+
+    public class GenericPerson<T> : ObservableValidator
+    {
+        [Required]
+        [MinLength(1)]
+        public string? Name { get; set; }
+
+        [Required]
+        public T? Value { get; set; }
+
+        public new void ValidateAllProperties()
+        {
+            base.ValidateAllProperties();
+        }
+    }
 }