Support self-registration of open-generic types

src/Injectio.Generators/ServiceRegistrationGenerator.cs

@@ -334,7 +334,7 @@ private static (EquatableArray<Diagnostic> diagnostics, bool hasServiceCollectio
         // no implementation type set, use class attribute is on
         if (implementationType.IsNullOrWhiteSpace())
         {
-            implementationType = classSymbol.ToDisplayString(_fullyQualifiedNullableFormat);
+            implementationType = ToNamedTypeWithoutPlaceholders(classSymbol).ToDisplayString(_fullyQualifiedNullableFormat);
         }
 
         // add implemented interfaces
@@ -345,7 +345,7 @@ private static (EquatableArray<Diagnostic> diagnostics, bool hasServiceCollectio
             {
                 // This interface is typically not injected into services and, more specifically, record types auto-implement it.
                 if(implementedInterface.ConstructedFrom.ToString() == "System.IEquatable<T>") continue;
-                var interfaceName = implementedInterface.ToDisplayString(_fullyQualifiedNullableFormat);
+                var interfaceName = ToNamedTypeWithoutPlaceholders(implementedInterface).ToDisplayString(_fullyQualifiedNullableFormat);
                 serviceTypes.Add(interfaceName);
             }
         }
@@ -366,6 +366,26 @@ private static (EquatableArray<Diagnostic> diagnostics, bool hasServiceCollectio
             tags.ToArray());
     }
 
+    private static INamedTypeSymbol ToNamedTypeWithoutPlaceholders(INamedTypeSymbol typeSymbol)
+    {
+        if (!typeSymbol.IsGenericType
+            || typeSymbol.IsUnboundGenericType)
+        {
+            return typeSymbol;
+        }
+
+        foreach (var typeArgument in typeSymbol.TypeArguments)
+        {
+            // If TypeKind is TypeParameter, it's actually the name of a locally declared type-parameter -> placeholder
+            if (typeArgument.TypeKind != TypeKind.TypeParameter)
+            {
+                return typeSymbol;
+            }
+        }
+
+        return typeSymbol.ConstructUnboundGenericType();
+    }
+
     private static bool IsKnownAttribute(AttributeData attribute, out string serviceLifetime)
     {
         if (IsSingletonAttribute(attribute))

tests/Injectio.Tests.Console/Program.cs

@@ -18,6 +18,7 @@
 var module = provider.GetRequiredService<IModuleService>();
 
 var generic = provider.GetRequiredService<IOpenGeneric<string>>();
+var generic2 = provider.GetRequiredService<IOpenGeneric2<string>>();
 var tagService = provider.GetService<IServiceTag>();
 
 var alpaService = provider.GetKeyedService<IServiceKeyed>("Alpha");

tests/Injectio.Tests.Library/Service.cs

@@ -79,6 +79,15 @@ public class OpenGeneric<T> : IOpenGeneric<T>
 {
 }
 
+public interface IOpenGeneric2<T>
+{
+}
+
+[RegisterSingleton]
+public class OpenGeneric2<T> : IOpenGeneric2<T>
+{
+}
+
 public interface IServiceTag
 {
 }

tests/Injectio.Tests/ServiceRegistrationGeneratorTests.cs

@@ -396,6 +396,58 @@ public class OpenGeneric<T> : IOpenGeneric<T>
             .ScrubLinesContaining("GeneratedCodeAttribute");
     }
 
+    [Fact]
+    public Task GenerateRegisterSingletonSelfAsOpenGeneric()
+    {
+        var source = @"
+using Injectio.Attributes;
+
+namespace Injectio.Sample;
+
+public interface IOpenGeneric<T>
+{ }
+
+[RegisterSingleton]
+public class OpenGeneric<T> : IOpenGeneric<T>
+{ }
+";
+
+        var (diagnostics, output) = GetGeneratedOutput<ServiceRegistrationGenerator>(source);
+
+        diagnostics.Should().BeEmpty();
+
+        return Verifier
+            .Verify(output)
+            .UseDirectory("Snapshots")
+            .ScrubLinesContaining("GeneratedCodeAttribute");
+    }
+
+    [Fact]
+    public Task GenerateRegisterSingletonSelfAsClosedGeneric()
+    {
+        var source = @"
+using Injectio.Attributes;
+
+namespace Injectio.Sample;
+
+public interface IClosedGeneric<T>
+{ }
+
+[RegisterSingleton]
+public class Service : IClosedGeneric<object>
+{ }
+";
+
+        var (diagnostics, output) = GetGeneratedOutput<ServiceRegistrationGenerator>(source);
+
+        diagnostics.Should().BeEmpty();
+
+        return Verifier
+            .Verify(output)
+            .UseDirectory("Snapshots")
+            .ScrubLinesContaining("GeneratedCodeAttribute");
+    }
+
     [Fact]
     public Task GenerateRegisterSingletonTags()
     {

tests/Injectio.Tests/Snapshots/ServiceRegistrationGeneratorTests.GenerateRegisterSingletonSelfAsClosedGeneric.verified.txt

@@ -0,0 +1,42 @@
+// <auto-generated />
+#nullable enable
+
+namespace Microsoft.Extensions.DependencyInjection
+{
+    /// <summary>
+    /// Extension methods for discovered service registrations
+    /// </summary>
+    public static class DiscoveredServicesExtensions
+    {
+        /// <summary>
+        /// Adds discovered services from Test.Generator to the specified service collection
+        /// </summary>
+        /// <param name="serviceCollection">The service collection.</param>
+        /// <param name="tags">The service registration tags to include.</param>
+        /// <returns>The service collection</returns>
+        public static global::Microsoft.Extensions.DependencyInjection.IServiceCollection AddTestGenerator(this global::Microsoft.Extensions.DependencyInjection.IServiceCollection serviceCollection, params string[]? tags)
+        {
+            var tagSet = new global::System.Collections.Generic.HashSet<string>(tags ?? global::System.Linq.Enumerable.Empty<string>());
+
+            global::Microsoft.Extensions.DependencyInjection.Extensions.ServiceCollectionDescriptorExtensions.TryAdd(
+                serviceCollection,
+                global::Microsoft.Extensions.DependencyInjection.ServiceDescriptor.Describe(
+                    typeof(global::Injectio.Sample.IClosedGeneric<object>),
+                    typeof(global::Injectio.Sample.Service),
+                    global::Microsoft.Extensions.DependencyInjection.ServiceLifetime.Singleton
+                )
+            );
+
+            global::Microsoft.Extensions.DependencyInjection.Extensions.ServiceCollectionDescriptorExtensions.TryAdd(
+                serviceCollection,
+                global::Microsoft.Extensions.DependencyInjection.ServiceDescriptor.Describe(
+                    typeof(global::Injectio.Sample.Service),
+                    typeof(global::Injectio.Sample.Service),
+                    global::Microsoft.Extensions.DependencyInjection.ServiceLifetime.Singleton
+                )
+            );
+
+            return serviceCollection;
+        }
+    }
+}

tests/Injectio.Tests/Snapshots/ServiceRegistrationGeneratorTests.GenerateRegisterSingletonSelfAsOpenGeneric.verified.txt

@@ -0,0 +1,42 @@
+// <auto-generated />
+#nullable enable
+
+namespace Microsoft.Extensions.DependencyInjection
+{
+    /// <summary>
+    /// Extension methods for discovered service registrations
+    /// </summary>
+    public static class DiscoveredServicesExtensions
+    {
+        /// <summary>
+        /// Adds discovered services from Test.Generator to the specified service collection
+        /// </summary>
+        /// <param name="serviceCollection">The service collection.</param>
+        /// <param name="tags">The service registration tags to include.</param>
+        /// <returns>The service collection</returns>
+        public static global::Microsoft.Extensions.DependencyInjection.IServiceCollection AddTestGenerator(this global::Microsoft.Extensions.DependencyInjection.IServiceCollection serviceCollection, params string[]? tags)
+        {
+            var tagSet = new global::System.Collections.Generic.HashSet<string>(tags ?? global::System.Linq.Enumerable.Empty<string>());
+
+            global::Microsoft.Extensions.DependencyInjection.Extensions.ServiceCollectionDescriptorExtensions.TryAdd(
+                serviceCollection,
+                global::Microsoft.Extensions.DependencyInjection.ServiceDescriptor.Describe(
+                    typeof(global::Injectio.Sample.IOpenGeneric<>),
+                    typeof(global::Injectio.Sample.OpenGeneric<>),
+                    global::Microsoft.Extensions.DependencyInjection.ServiceLifetime.Singleton
+                )
+            );
+
+            global::Microsoft.Extensions.DependencyInjection.Extensions.ServiceCollectionDescriptorExtensions.TryAdd(
+                serviceCollection,
+                global::Microsoft.Extensions.DependencyInjection.ServiceDescriptor.Describe(
+                    typeof(global::Injectio.Sample.OpenGeneric<>),
+                    typeof(global::Injectio.Sample.OpenGeneric<>),
+                    global::Microsoft.Extensions.DependencyInjection.ServiceLifetime.Singleton
+                )
+            );
+
+            return serviceCollection;
+        }
+    }
+}