Resolving issue with Optional Generic Parameter

Fixed #293

package.props

@@ -1,7 +1,7 @@
 <Project>
 
   <PropertyGroup>
-    <VersionBase>5.11.9</VersionBase>
+    <VersionBase>5.11.10</VersionBase>
     <PackageReleaseNotes>This package is compatible with .NET Standard 1.0 and 2.0, .NET Core 1.0 and 2.0, .NET 4.0, 4.5, 4.6, 4.7</PackageReleaseNotes>
   </PropertyGroup>
 

src/Processors/Abstracts/MemberExpression.cs

@@ -12,13 +12,15 @@ namespace Unity.Processors
 
         protected virtual IEnumerable<Expression> ExpressionsFromSelection(Type type, IEnumerable<object> members)
         {
+            HashSet<TMemberInfo> memberSet = new HashSet<TMemberInfo>();
+
             foreach (var member in members)
             {
-
                 switch (member)
                 {
                     // TMemberInfo
                     case TMemberInfo info:
+                        if (!memberSet.Add(info)) continue;
                         object value = DependencyAttribute.Instance; 
                         foreach (var node in AttributeFactories)
                         {
@@ -34,8 +36,9 @@ namespace Unity.Processors
                     
                         // Injection Member
                     case InjectionMember<TMemberInfo, TData> injectionMember:
-                        yield return GetResolverExpression(injectionMember.MemberInfo(type), 
-                                                           injectionMember.Data);
+                        var selection = injectionMember.MemberInfo(type);
+                        if (!memberSet.Add(selection)) continue;
+                        yield return GetResolverExpression(selection, injectionMember.Data);
                         break;
 
                     // Unknown

src/Processors/Abstracts/MemberProcessor.cs

@@ -154,8 +154,8 @@ namespace Unity.Processors
         public override ResolveDelegate<BuilderContext> GetResolver(Type type, IPolicySet registration, ResolveDelegate<BuilderContext> seed)
         {
             var selector = GetPolicy<ISelect<TMemberInfo>>(registration);
-            var members = selector.Select(type, registration);
-            var resolvers = ResolversFromSelection(type, members).ToArray();
+            var members = selector.Select(type, registration); 
+            var resolvers = ResolversFromSelection(type, members).Distinct().ToArray();
 
             return (ref BuilderContext c) =>
             {
@@ -172,14 +172,12 @@ namespace Unity.Processors
 
         public virtual IEnumerable<object> Select(Type type, IPolicySet registration)
         {
-            HashSet<object> memberSet = new HashSet<object>();
-
             // Select Injected Members
             if (null != ((InternalRegistration)registration).InjectionMembers)
             {
                 foreach (var injectionMember in ((InternalRegistration)registration).InjectionMembers)
                 {
-                    if (injectionMember is InjectionMember<TMemberInfo, TData> && memberSet.Add(injectionMember))
+                    if (injectionMember is InjectionMember<TMemberInfo, TData>)
                         yield return injectionMember;
                 }
             }
@@ -193,12 +191,10 @@ namespace Unity.Processors
                 for (var i = 0; i < AttributeFactories.Length; i++)
                 {
 #if NET40
-                    if (!member.IsDefined(AttributeFactories[i].Type, true) ||
+                    if (!member.IsDefined(AttributeFactories[i].Type, true)) continue;
 #else
-                    if (!member.IsDefined(AttributeFactories[i].Type) || 
+                    if (!member.IsDefined(AttributeFactories[i].Type)) continue;
 #endif
-                        !memberSet.Add(member)) continue;
-
                     yield return member;
                     break;
                 }

src/Processors/Abstracts/MemberResolution.cs

@@ -3,7 +3,6 @@ using System.Collections.Generic;
 using System.Reflection;
 using Unity.Builder;
 using Unity.Injection;
-using Unity.Policy;
 using Unity.Resolution;
 
 namespace Unity.Processors
@@ -14,12 +13,15 @@ namespace Unity.Processors
 
         protected virtual IEnumerable<ResolveDelegate<BuilderContext>> ResolversFromSelection(Type type, IEnumerable<object> members)
         {
+            HashSet<TMemberInfo> memberSet = new HashSet<TMemberInfo>();
+
             foreach (var member in members)
             {
                 switch (member)
                 {
                     // MemberInfo
                     case TMemberInfo info:
+                        if (!memberSet.Add(info)) continue;
                         object value = DependencyAttribute.Instance;
                         foreach (var node in AttributeFactories)
                         {
@@ -34,8 +36,9 @@ namespace Unity.Processors
 
                     // Injection Member
                     case InjectionMember<TMemberInfo, TData> injectionMember:
-                        yield return GetResolverDelegate(injectionMember.MemberInfo(type), 
-                                                         injectionMember.Data);
+                        var selection = injectionMember.MemberInfo(type);
+                        if (!memberSet.Add(selection)) continue;
+                        yield return GetResolverDelegate(selection, injectionMember.Data);
                         break;
 
                     // Unknown

src/Processors/Methods/MethodProcessor.cs

@@ -34,6 +34,7 @@ namespace Unity.Processors
 
         #endregion
 
+
         #region Expression 
 
         protected override Expression GetResolverExpression(MethodInfo info, object resolvers)

tests/Unity.Tests/Issues/GitHub.cs

@@ -1,6 +1,7 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using System;
 using System.Diagnostics;
+using Unity.Injection;
 using Unity.Lifetime;
 using Unity.Resolution;
 
@@ -222,6 +223,37 @@ namespace Unity.Tests.v5.Issues
             Assert.AreEqual(main2, main2.HelperClass.HostClass);
         }
 
+        public class BaselineTestType<TDependency>
+        {
+            [Dependency] public TDependency Field;
+
+            public object Value { get => Field; protected set => throw new NotSupportedException(); }
+            public object Expected => default(TDependency);
+        }
+
+        [TestMethod]
+        public void unitycontainer_container_293()
+        {
+            var unnamed = 55;
+            var named = 22;
+            var name = "Name";
+
+            // Create root container and register classes in root
+            IUnityContainer container = new UnityContainer();
+
+            container.RegisterType(typeof(BaselineTestType<>), new InjectionField("Field", new OptionalGenericParameter("TDependency", name)));
+
+            var instance = container.Resolve<BaselineTestType<int>>();
+            Assert.IsNotNull(instance);
+            Assert.AreEqual(0, instance.Field);
+
+            container.RegisterInstance(unnamed)
+                     .RegisterInstance(name, named);
+            
+            instance = container.Resolve<BaselineTestType<int>>();
+            Assert.IsNotNull(instance);
+            Assert.AreEqual(named, instance.Field);
+        }
     }
 
     public class MainClass : IHostClass