Fix issue: ConventionsBuilder and open generic export with constructor dependencies

src/libraries/System.Composition.TypedParts/src/System/Composition/TypedParts/Discovery/DiscoveredPart.cs

@@ -98,6 +98,11 @@ private IEnumerable<CompositionDependency> GetPartActivatorDependencies(Dependen
                     }
                 }
 
+                if (_constructor == null && _partType.IsGenericType)
+                {
+                    _constructor = GetConstructorInfoFromGenericType(_partType);
+                }
+
                 if (_constructor == null)
                     _constructor = _partType.DeclaredConstructors
                         .FirstOrDefault(ci => ci.IsPublic && !(ci.IsStatic || ci.GetParameters().Any()));
@@ -130,6 +135,34 @@ private IEnumerable<CompositionDependency> GetPartActivatorDependencies(Dependen
             }
         }
 
+        private ConstructorInfo GetConstructorInfoFromGenericType(TypeInfo type)
+        {
+            var genericPartType = type.GetGenericTypeDefinition();
+            var genericPartTypeInfo = genericPartType.GetTypeInfo();
+            ConstructorInfo constructor = null;
+
+            int index = -1;
+            foreach (var c in genericPartTypeInfo.DeclaredConstructors)
+            {
+                ++index;
+
+                if (!c.IsPublic || c.IsStatic) continue;
+
+                if (_attributeContext.GetDeclaredAttribute<ImportingConstructorAttribute>(genericPartType, c) != null)
+                {
+                    if (constructor != null)
+                    {
+                        string message = SR.Format(SR.DiscoveredPart_MultipleImportingConstructorsFound, type);
+                        throw new CompositionFailedException(message);
+                    }
+
+                    constructor = type.DeclaredConstructors.ElementAt(index);
+                }
+            }
+
+            return constructor;
+        }
+
         public CompositeActivator GetActivator(DependencyAccessor definitionAccessor, IEnumerable<CompositionDependency> dependencies)
         {
             if (_partActivator != null) return _partActivator;

src/libraries/System.Composition.TypedParts/tests/ContainerConfigurationTests.cs

@@ -7,6 +7,7 @@
 using System.Composition.Convention;
 using System.Composition.Hosting.Core;
 using System.Diagnostics;
+using System.Linq;
 using System.Reflection;
 using Xunit;
 
@@ -591,5 +592,45 @@ public void DebuggerAttributes_GetViaReflection_Success(ContainerConfiguration c
                 Assert.NotNull(property.GetValue(debuggerAttributeInfo.Instance));
             }
         }
+
+        [Fact]
+        public void CreateContiner_GenericExportWithDependencyConstructorHasConvention_Success()
+        {
+            var conventions = new ConventionBuilder();
+
+            conventions
+                .ForType<Dependency>()
+                .Export<Dependency>();
+
+            conventions
+                .ForType(typeof(MoreOpenWithDependency<>))
+                .ExportInterfaces(
+                    (i) => i.GetGenericTypeDefinition() == typeof(IOpen<>),
+                    (type, builder) => builder.AsContractType(typeof(IOpen<>)))
+                .SelectConstructor(ctors => ctors.ElementAt(0));
+
+            var configuration = new ContainerConfiguration()
+                .WithParts(new[] { typeof(IOpen<>), typeof(MoreOpenWithDependency<>), typeof(Dependency) }, conventions);
+
+            using (var container = configuration.CreateContainer())
+            {
+                var service = container.GetExport(typeof(IOpen<object>)) as MoreOpenWithDependency<object>;
+                Assert.NotNull(service);
+                Assert.NotNull(service.Dependency);
+            }
+        }
+        public interface IOpen<T>
+        {
+        }
+        public class MoreOpenWithDependency<T> : IOpen<T>
+        {
+            public Dependency Dependency { get; set; }
+            public MoreOpenWithDependency(Dependency dep)
+            {
+                Dependency = dep;
+            }
+        }
+
+        public class Dependency { }
     }
 }