Capture prop injection instance when the middleware runs

src/Autofac/Builder/RegistrationBuilder{TLimit,TActivatorData,TRegistrationStyle}.cs

@@ -584,11 +584,13 @@ public RegistrationBuilder(Service defaultService, TActivatorData activatorData,
 
                 if (allowCircularDependencies)
                 {
+                    var capturedInstance = ctxt.Instance;
+
                     // If we are allowing circular deps, then we need to run when all requests have completed (similar to Activated).
                     ctxt.RequestCompleting += (o, args) =>
                     {
                         var evCtxt = args.RequestContext;
-                        AutowiringPropertyInjector.InjectProperties(evCtxt, evCtxt.Instance!, propertySelector, evCtxt.Parameters);
+                        AutowiringPropertyInjector.InjectProperties(evCtxt, capturedInstance!, propertySelector, evCtxt.Parameters);
                     };
                 }
                 else

test/Autofac.Specification.Test/Features/PropertyInjectionTests.cs

@@ -373,6 +373,22 @@ public void SetterInjectionPrivateGet()
             Assert.False(instance.GetterCalled);
         }
 
+        [Fact]
+        public void DecoratedInstanceWithPropertyInjectionAllowingCircularReferencesStillInjects()
+        {
+            var val = "Value";
+
+            var builder = new ContainerBuilder();
+            builder.RegisterInstance(val);
+            builder.RegisterType<DecoratedService>().As<IMyService>().PropertiesAutowired(PropertyWiringOptions.AllowCircularDependencies);
+            builder.RegisterDecorator<ServiceDecorator, IMyService>();
+
+            var container = builder.Build();
+            var instance = container.Resolve<IMyService>();
+
+            instance.AssertProp();
+        }
+
         private class ConstructorParamNotAttachedToProperty
         {
             [SuppressMessage("SA1401", "SA1401")]
@@ -411,5 +427,38 @@ private get
                 }
             }
         }
+
+        private interface IMyService
+        {
+            void AssertProp();
+        }
+
+        private sealed class DecoratedService : IMyService
+        {
+            public string Prop { get; set; }
+
+            public void AssertProp()
+            {
+                if (Prop is null)
+                {
+                    throw new NullReferenceException();
+                }
+            }
+        }
+
+        private sealed class ServiceDecorator : IMyService
+        {
+            private readonly IMyService _decorating;
+
+            public ServiceDecorator(IMyService decorating)
+            {
+                _decorating = decorating;
+            }
+
+            public void AssertProp()
+            {
+                _decorating.AssertProp();
+            }
+        }
     }
 }