Resolved #929: Resetting resolve op activation stack on succeed or fa…

…il to allow try/catch in lambda registrations.

src/Autofac/Core/Resolving/ResolveOperation.cs

@@ -121,17 +121,26 @@ public object GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, I
             var handler = InstanceLookupBeginning;
             handler?.Invoke(this, new InstanceLookupBeginningEventArgs(activation));
 
-            var instance = activation.Execute();
-            _successfulActivations.Add(activation);
-
-            _activationStack.Pop();
+            try
+            {
+                var instance = activation.Execute();
+                _successfulActivations.Add(activation);
 
-            if (_activationStack.Count == 0)
-                CompleteActivations();
+                return instance;
+            }
+            finally
+            {
+                // Issue #929: Allow the activation stack to be popped even if the activation failed.
+                // This allows try/catch to happen in lambda registrations without corrupting the stack.
+                _activationStack.Pop();
 
-            --_callDepth;
+                if (_activationStack.Count == 0)
+                {
+                    CompleteActivations();
+                }
 
-            return instance;
+                --_callDepth;
+            }
         }
 
         public event EventHandler<ResolveOperationEndingEventArgs> CurrentOperationEnding;

test/Autofac.Test/Core/Resolving/ResolveOperationTests.cs

@@ -38,6 +38,36 @@ public void ActivatingArgsSuppliesParameters()
             Assert.Equal(provided, passed);
         }
 
+        [Fact]
+        public void ActivationStackResetsOnFailedLambdaResolve()
+        {
+            // Issue #929
+            var builder = new ContainerBuilder();
+            builder.RegisterType<ServiceImpl>().AsSelf();
+            builder.Register<IService>(c =>
+            {
+                try
+                {
+                    // This will fail because ServiceImpl needs a Guid ctor
+                    // parameter and it's not provided.
+                    return c.Resolve<ServiceImpl>();
+                }
+                catch (Exception)
+                {
+                    // This is where the activation stack isn't getting reset.
+                }
+
+                return new ServiceImpl(Guid.Empty);
+            });
+            builder.RegisterType<Dependency>().AsSelf();
+            builder.RegisterType<ComponentConsumer>().AsSelf();
+            var container = builder.Build();
+
+            // This throws a circular dependency exception if the activation stack
+            // doesn't get reset.
+            container.Resolve<ComponentConsumer>();
+        }
+
         [Fact]
         public void AfterTheOperationIsFinished_ReusingTheTemporaryContextThrows()
         {
@@ -150,5 +180,51 @@ public void PropertyInjectionPassesNamedParameterOfTheInstanceTypeBeingInjectedO
             var instanceType = capturedparameters.Named<Type>(ResolutionExtensions.PropertyInjectedInstanceTypeNamedParameter);
             Assert.Equal(existingInstance.GetType(), instanceType);
         }
+
+        private interface IService
+        {
+        }
+
+        // Issue #929
+        // When a resolve operation fails in a lambda registration the activation stack
+        // doesn't get reset and incorrectly causes a circular dependency exception.
+        //
+        // The ComponentConsumer takes IService (ServiceImpl) and a Dependency; the
+        // Dependency also takes an IService. Normally this wouldn't cause an issue, but
+        // if the registration for IService is a lambda that has a try/catch around a failing
+        // resolve, the activation stack won't reset and the IService will be seen as a
+        // circular dependency.
+        private class ComponentConsumer
+        {
+            private Dependency _dependency;
+
+            private IService _service;
+
+            public ComponentConsumer(IService service, Dependency dependency)
+            {
+                this._service = service;
+                this._dependency = dependency;
+            }
+        }
+
+        private class Dependency
+        {
+            private IService _service;
+
+            public Dependency(IService service)
+            {
+                this._service = service;
+            }
+        }
+
+        private class ServiceImpl : IService
+        {
+            private Guid _id;
+
+            public ServiceImpl(Guid id)
+            {
+                this._id = id;
+            }
+        }
     }
 }