Merge pull request #260 from CommunityToolkit/dev/disable-generation-for-abstracts

Disable source generators for abstract types

Author: Sergio0694

CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/ObservableValidatorValidateAllPropertiesGenerator.cs

@@ -20,13 +20,15 @@ public sealed partial class ObservableValidatorValidateAllPropertiesGenerator :
     /// <inheritdoc/>
     public void Initialize(IncrementalGeneratorInitializationContext context)
     {
-        // Get all class declarations
+        // Get all class declarations. We intentionally skip generating code for abstract types, as that would never be used.
+        // The methods that are generated by this generator are retrieved through reflection using the type of the invoking
+        // instance as discriminator, which means a type that is abstract could never be used (since it couldn't be instantiated).
         IncrementalValuesProvider<INamedTypeSymbol> typeSymbols =
             context.SyntaxProvider
             .CreateSyntaxProvider(
                 static (node, _) => node is ClassDeclarationSyntax,
                 static (context, _) => (context.Node, Symbol: (INamedTypeSymbol)context.SemanticModel.GetDeclaredSymbol(context.Node)!))
-            .Where(static item => item.Node.IsFirstSyntaxDeclarationForSymbol(item.Symbol))
+            .Where(static item => !item.Symbol.IsAbstract && item.Node.IsFirstSyntaxDeclarationForSymbol(item.Symbol))
             .Select(static (item, _) => item.Symbol);
 
         // Get the types that inherit from ObservableValidator and gather their info

CommunityToolkit.Mvvm.SourceGenerators/Messaging/IMessengerRegisterAllGenerator.cs

@@ -25,12 +25,13 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
         // definitions (it might happen if a recipient has partial declarations). To do this, all pairs
         // of class declarations and associated symbols are gathered, and then only the pair where the
         // class declaration is the first syntax reference for the associated symbol is kept.
+        // Just like with the ObservableValidator generator, we also intentionally skip abstract types.
         IncrementalValuesProvider<INamedTypeSymbol> typeSymbols =
             context.SyntaxProvider
             .CreateSyntaxProvider(
                 static (node, _) => node is ClassDeclarationSyntax,
                 static (context, _) => (context.Node, Symbol: (INamedTypeSymbol)context.SemanticModel.GetDeclaredSymbol(context.Node)!))
-            .Where(static item => item.Node.IsFirstSyntaxDeclarationForSymbol(item.Symbol))
+            .Where(static item => !item.Symbol.IsAbstract && item.Node.IsFirstSyntaxDeclarationForSymbol(item.Symbol))
             .Select(static (item, _) => item.Symbol);
 
         // Get the target IRecipient<TMessage> interfaces and filter out other types

tests/CommunityToolkit.Mvvm.UnitTests/Test_IRecipientGenerator.cs

@@ -3,6 +3,8 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
+using System.Linq;
+using System.Reflection;
 using CommunityToolkit.Mvvm.Messaging;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
@@ -52,9 +54,20 @@ public void Test_IRecipientGenerator_TypeWithMultipleClassDeclarations()
         _ = Messaging.__Internals.__IMessengerExtensions.CreateAllMessagesRegistratorWithToken<int>(recipient);
     }
 
-    public sealed class RecipientWithSomeMessages :
-        IRecipient<MessageA>,
-        IRecipient<MessageB>
+    [TestMethod]
+    public void Test_IRecipientGenerator_AbstractTypesDoNotTriggerCodeGeneration()
+    {
+        MethodInfo? createAllPropertiesValidatorMethod = typeof(Messaging.__Internals.__IMessengerExtensions)
+            .GetMethods(BindingFlags.Static | BindingFlags.Public)
+            .Where(static m => m.Name == "CreateAllMessagesRegistratorWithToken")
+            .Where(static m => m.GetParameters() is { Length: 1 } parameters && parameters[0].ParameterType == typeof(AbstractModelWithValidatablePropertyIRecipientInterfaces))
+            .FirstOrDefault();
+
+        // We need to validate that no methods are generated for abstract types, so we just check this method doesn't exist
+        Assert.IsNull(createAllPropertiesValidatorMethod);
+    }
+
+    public sealed class RecipientWithSomeMessages : IRecipient<MessageA>, IRecipient<MessageB>
     {
         public MessageA? A { get; private set; }
 
@@ -91,4 +104,14 @@ public void Receive(MessageA message)
     partial class RecipientWithMultipleClassDeclarations
     {
     }
+
+    public abstract class AbstractModelWithValidatablePropertyIRecipientInterfaces : IRecipient<MessageA>, IRecipient<MessageB>
+    {
+        public abstract void Receive(MessageA message);
+
+        public void Receive(MessageB message)
+        {
+
+        }
+    }
 }

tests/CommunityToolkit.Mvvm.UnitTests/Test_ObservableValidator.cs

@@ -526,6 +526,19 @@ public void Test_ObservableValidator_VerifyTrimmingAnnotation()
 #endif
     }
 
+    [TestMethod]
+    public void Test_ObservableRecipient_AbstractTypesDoNotTriggerCodeGeneration()
+    {
+        MethodInfo? createAllPropertiesValidatorMethod = typeof(ComponentModel.__Internals.__ObservableValidatorExtensions)
+            .GetMethods(BindingFlags.Static | BindingFlags.Public)
+            .Where(static m => m.Name == "CreateAllPropertiesValidator")
+            .Where(static m => m.GetParameters() is { Length: 1 } parameters && parameters[0].ParameterType == typeof(AbstractModelWithValidatableProperty))
+            .FirstOrDefault();
+
+        // We need to validate that no methods are generated for abstract types, so we just check this method doesn't exist
+        Assert.IsNull(createAllPropertiesValidatorMethod);
+    }
+
     public class Person : ObservableValidator
     {
         private string? name;
@@ -777,4 +790,11 @@ public partial class PersonWithPartialDeclaration
         [Range(10, 1000)]
         public int Number { get; set; }
     }
+
+    public abstract class AbstractModelWithValidatableProperty : ObservableValidator
+    {
+        [Required]
+        [MinLength(2)]
+        public string? Name { get; set; }
+    }
 }