Add support for enumerating keyed services with KeyedService.AnyKey

src/libraries/Microsoft.Extensions.DependencyInjection.Specification.Tests/src/KeyedDependencyInjectionSpecificationTests.cs

@@ -100,6 +100,61 @@ public void ResolveKeyedServices()
             Assert.Equal(new[] { service2, service3, service4 }, services);
         }
 
+        [Fact]
+        public void ResolveKeyedServicesAnyKey()
+        {
+            var service1 = new Service();
+            var service2 = new Service();
+            var service3 = new Service();
+            var service4 = new Service();
+            var service5 = new Service();
+            var service6 = new Service();
+            var serviceCollection = new ServiceCollection();
+            serviceCollection.AddKeyedSingleton<IService>("first-service", service1);
+            serviceCollection.AddKeyedSingleton<IService>("service", service2);
+            serviceCollection.AddKeyedSingleton<IService>("service", service3);
+            serviceCollection.AddKeyedSingleton<IService>("service", service4);
+            serviceCollection.AddKeyedSingleton<IService>(null, service5);
+            serviceCollection.AddSingleton<IService>(service6);
+
+            var provider = CreateServiceProvider(serviceCollection);
+
+
+            // Return all services registered with a non null key
+            var allServices = provider.GetKeyedServices<IService>(KeyedService.AnyKey).ToList();
+            Assert.Equal(4, allServices.Count);
+            Assert.Equal(new[] { service1, service2, service3, service4 }, allServices);
+        }
+
+        [Fact]
+        public void ResolveKeyedServicesAnyKeyWithAnyKeyRegistration()
+        {
+            var service1 = new Service();
+            var service2 = new Service();
+            var service3 = new Service();
+            var service4 = new Service();
+            var service5 = new Service();
+            var service6 = new Service();
+            var serviceCollection = new ServiceCollection();
+            serviceCollection.AddKeyedTransient<IService>(KeyedService.AnyKey, (sp, key) => new Service());
+            serviceCollection.AddKeyedSingleton<IService>("first-service", service1);
+            serviceCollection.AddKeyedSingleton<IService>("service", service2);
+            serviceCollection.AddKeyedSingleton<IService>("service", service3);
+            serviceCollection.AddKeyedSingleton<IService>("service", service4);
+            serviceCollection.AddKeyedSingleton<IService>(null, service5);
+            serviceCollection.AddSingleton<IService>(service6);
+
+            var provider = CreateServiceProvider(serviceCollection);
+
+            _ = provider.GetKeyedService<IService>("something-else");
+            _ = provider.GetKeyedService<IService>("something-else-again");
+
+            // Return all services registered with a non null key, but not the one "created" with KeyedService.AnyKey
+            var allServices = provider.GetKeyedServices<IService>(KeyedService.AnyKey).ToList();
+            Assert.Equal(5, allServices.Count);
+            Assert.Equal(new[] { service1, service2, service3, service4 }, allServices.Skip(1));
+        }
+
         [Fact]
         public void ResolveKeyedGenericServices()
         {

src/libraries/Microsoft.Extensions.DependencyInjection/src/ServiceLookup/CallSiteFactory.cs

@@ -283,7 +283,10 @@ private static bool AreCompatible(DynamicallyAccessedMemberTypes serviceDynamica
                 ServiceCallSite[] callSites;
 
                 // If item type is not generic we can safely use descriptor cache
+                // Special case for KeyedService.AnyKey, we don't want to check the cache because a KeyedService.AnyKey registration
+                // will "hide" all the other service registration
                 if (!itemType.IsConstructedGenericType &&
+                    !KeyedService.AnyKey.Equals(cacheKey.ServiceKey) &&
                     _descriptorLookup.TryGetValue(cacheKey, out ServiceDescriptorCacheItem descriptors))
                 {
                     callSites = new ServiceCallSite[descriptors.Count];
@@ -694,7 +697,11 @@ private static bool KeysMatch(object? key1, object? key2)
                 return true;
 
             if (key1 != null && key2 != null)
-                return key1.Equals(KeyedService.AnyKey) || key1.Equals(key2);
+            {
+                return key1.Equals(key2)
+                    || key1.Equals(KeyedService.AnyKey)
+                    || key2.Equals(KeyedService.AnyKey);
+            }
 
             return false;
         }