Use 'keyed service' code only for .net 8 and newer versions

src/Lamar.AspNetCoreTests/Bugs/Bug_395_keyed_service_closed_generic_interface_registration_check.cs

@@ -9,6 +9,7 @@
 
 namespace Lamar.AspNetCoreTests.Bugs;
 
+#if NET8_0_OR_GREATER
 public class Bug_395_keyed_service_closed_generic_interface_registration_check
 {
     class ClassA {}
@@ -45,4 +46,5 @@ public void do_not_blow_up()
                 .ShouldNotBeNull();
         }
     }
-}
+}
+#endif

src/Lamar.Testing/IoC/Acceptance/IKeyedServiceProvider_compliance.cs

@@ -8,7 +8,7 @@ namespace Lamar.Testing.IoC.Acceptance;
 
 public class IKeyedServiceProvider_compliance
 {
-    #region sample_adding_keyed_services
+    #if NET8_0_OR_GREATER
 
     [Fact]
     public void register_by_name_using_dot_net_core_syntax()
@@ -44,5 +44,5 @@ public void register_by_name_using_dot_net_core_syntax()
             .ShouldNotBeSameAs(container.GetKeyedService<CWidget>("C3"));
     }
 
-    #endregion
+    #endif
 }

src/Lamar/IServiceContext.cs

@@ -8,7 +8,10 @@
 
 namespace Lamar;
 
-public interface IServiceContext : IServiceProvider, IDisposable, IAsyncDisposable, IKeyedServiceProvider
+public interface IServiceContext : IServiceProvider, IDisposable, IAsyncDisposable
+#if NET8_0_OR_GREATER
+    , IKeyedServiceProvider
+#endif
 {
     /// <summary>
     ///     Provides queryable access to the configured serviceType's and Instances of this Container.

src/Lamar/IoC/Instances/Instance.cs

@@ -106,10 +106,12 @@ internal IEnumerable<Assembly> ReferencedAssemblies()
 
     public static Instance For(ServiceDescriptor service)
     {
+        #if NET8_0_OR_GREATER
         if (service.IsKeyedService)
         {
             var name = service.ServiceKey?.ToString();
             Instance instance = null;
+
             if (service.KeyedImplementationInstance != null)
             {
                 instance = new ObjectInstance(service.ServiceType, service.KeyedImplementationInstance);
@@ -136,9 +138,8 @@ public static Instance For(ServiceDescriptor service)
             if (name.IsNotEmpty()) instance.Name = name;
 
             return instance;
-
-
         }
+        #endif
 
 
         if (service.ImplementationInstance is Instance i)

src/Lamar/ServiceGraph.cs

@@ -268,9 +268,7 @@ private ServiceFamily buildFamilyForInstanceGroup(IServiceCollection services,
 
     private ServiceFamily buildClosedGenericType(Type serviceType, IServiceCollection services)
     {
-        var closed = services.Where(x => x.ServiceType == serviceType && (x.IsKeyedService
-                ? !x.KeyedImplementationType.IsOpenGeneric()
-                : !x.ImplementationType.IsOpenGeneric()))
+        var closed = services.Where(x => x.ServiceType == serviceType && isKeyedServiceSupported(x))
             .Select(Instance.For);
 
         var templated = services
@@ -297,6 +295,17 @@ private ServiceFamily buildClosedGenericType(Type serviceType, IServiceCollectio
         return new ServiceFamily(serviceType, DecoratorPolicies, instances);
     }
 
+    private static bool isKeyedServiceSupported(ServiceDescriptor serviceDescriptor)
+    {
+        #if NET8_0_OR_GREATER
+         return serviceDescriptor.IsKeyedService
+                    ? !serviceDescriptor.KeyedImplementationType.IsOpenGeneric()
+                    : !serviceDescriptor.ImplementationType.IsOpenGeneric();
+        #endif
+
+        return !serviceDescriptor.ImplementationType.IsOpenGeneric();
+    }
+
     public IEnumerable<Instance> AllInstances()
     {
         var serviceFamilies = _families.Enumerate().Select(x => x.Value).Where(x => x != null).ToArray();