Linq: add enum HasFlag method support

src/NHibernate.Test/Async/NHSpecificTest/GH0829/Fixture.cs

@@ -0,0 +1,73 @@
+//------------------------------------------------------------------------------
+// <auto-generated>
+//     This code was generated by AsyncGenerator.
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+//------------------------------------------------------------------------------
+
+
+using System.Linq;
+using NUnit.Framework;
+using NHibernate.Linq;
+
+namespace NHibernate.Test.NHSpecificTest.GH0829
+{
+	using System.Threading.Tasks;
+	[TestFixture]
+	public class FixtureAsync : BugTestCase
+	{
+		protected override void OnSetUp()
+		{
+			using var session = OpenSession();
+			using var transaction = session.BeginTransaction();
+
+			var e1 = new Parent { Type = TestEnum.A | TestEnum.C };
+			session.Save(e1);
+
+			var e2 = new Child { Type = TestEnum.D, Parent = e1 };
+			session.Save(e2);
+
+			var e3 = new Child { Type = TestEnum.C, Parent = e1 };
+			session.Save(e3);
+
+			transaction.Commit();
+		}
+
+		[Test]
+		public async Task SelectClassAsync()
+		{
+			using var session = OpenSession();
+
+			var resultFound = await (session.Query<Parent>().Where(x => x.Type.HasFlag(TestEnum.A)).FirstOrDefaultAsync());
+
+			var resultNotFound = await (session.Query<Parent>().Where(x => x.Type.HasFlag(TestEnum.D)).FirstOrDefaultAsync());
+
+			Assert.That(resultFound, Is.Not.Null);
+			Assert.That(resultNotFound, Is.Null);
+		}
+
+		[Test]
+		public async Task SelectChildClassContainedInParentAsync()
+		{
+			using var session = OpenSession();
+
+			var result = await (session.Query<Child>().Where(x => x.Parent.Type.HasFlag(x.Type)).FirstOrDefaultAsync());
+
+			Assert.That(result, Is.Not.Null);
+		}
+
+		protected override void OnTearDown()
+		{
+			using var session = OpenSession();
+			using var transaction = session.BeginTransaction();
+			foreach (var entity in new[] { nameof(Child), nameof(Parent) })
+			{
+				session.CreateQuery($"delete from {entity}").ExecuteUpdate();
+			}
+
+			transaction.Commit();
+		}
+	}
+}

src/NHibernate.Test/NHSpecificTest/GH0829/Fixture.cs

@@ -0,0 +1,61 @@
+using System.Linq;
+using NUnit.Framework;
+
+namespace NHibernate.Test.NHSpecificTest.GH0829
+{
+	[TestFixture]
+	public class Fixture : BugTestCase
+	{
+		protected override void OnSetUp()
+		{
+			using var session = OpenSession();
+			using var transaction = session.BeginTransaction();
+
+			var e1 = new Parent { Type = TestEnum.A | TestEnum.C };
+			session.Save(e1);
+
+			var e2 = new Child { Type = TestEnum.D, Parent = e1 };
+			session.Save(e2);
+
+			var e3 = new Child { Type = TestEnum.C, Parent = e1 };
+			session.Save(e3);
+
+			transaction.Commit();
+		}
+
+		[Test]
+		public void SelectClass()
+		{
+			using var session = OpenSession();
+
+			var resultFound = session.Query<Parent>().Where(x => x.Type.HasFlag(TestEnum.A)).FirstOrDefault();
+
+			var resultNotFound = session.Query<Parent>().Where(x => x.Type.HasFlag(TestEnum.D)).FirstOrDefault();
+
+			Assert.That(resultFound, Is.Not.Null);
+			Assert.That(resultNotFound, Is.Null);
+		}
+
+		[Test]
+		public void SelectChildClassContainedInParent()
+		{
+			using var session = OpenSession();
+
+			var result = session.Query<Child>().Where(x => x.Parent.Type.HasFlag(x.Type)).FirstOrDefault();
+
+			Assert.That(result, Is.Not.Null);
+		}
+
+		protected override void OnTearDown()
+		{
+			using var session = OpenSession();
+			using var transaction = session.BeginTransaction();
+			foreach (var entity in new[] { nameof(Child), nameof(Parent) })
+			{
+				session.CreateQuery($"delete from {entity}").ExecuteUpdate();
+			}
+
+			transaction.Commit();
+		}
+	}
+}

src/NHibernate.Test/NHSpecificTest/GH0829/Mappings.hbm.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="NHibernate.Test" namespace="NHibernate.Test.NHSpecificTest.GH0829">
+  <class name="Parent" table="parent">
+    <id name="Id" generator="guid.comb" />
+    <property name="Type" type="NHibernate.Type.EnumType`1[[NHibernate.Test.NHSpecificTest.GH0829.TestEnum, NHibernate.Test]], NHibernate"/>
+    <bag name="Children" lazy="true">
+      <key column="ParentId" />
+      <one-to-many class="Child" />
+    </bag>
+  </class>
+
+  <class name="Child" table="Child">
+    <id name="Id" generator="guid.comb" />
+    <property name="Type" type="NHibernate.Type.EnumType`1[[NHibernate.Test.NHSpecificTest.GH0829.TestEnum, NHibernate.Test]], NHibernate"/>
+    <many-to-one name="Parent" column="ParentId" not-null="true" />
+  </class>
+</hibernate-mapping>

src/NHibernate.Test/NHSpecificTest/GH0829/Model.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Collections.Generic;
+
+namespace NHibernate.Test.NHSpecificTest.GH0829
+{
+	public class Parent
+	{
+		public virtual Guid Id { get; set; }
+
+		public virtual TestEnum Type { get; set; }
+
+		public virtual IList<Child> Children { get; set; } = new List<Child>();
+	}
+
+	public class Child
+	{
+		public virtual Guid Id { get; set; }
+
+		public virtual TestEnum Type { get; set; }
+
+		public virtual Parent Parent { get; set; }
+	}
+}

src/NHibernate.Test/NHSpecificTest/GH0829/TestEnum.cs

@@ -0,0 +1,13 @@
+using System;
+
+namespace NHibernate.Test.NHSpecificTest.GH0829
+{
+	[Flags]
+	public enum TestEnum
+	{
+		A = 1 << 0,
+		B = 1 << 1,
+		C = 1 << 2,
+		D = 1 << 3
+	}
+}

src/NHibernate/Linq/ExpressionTransformers/RemoveRedundantCast.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Linq.Expressions;
 using NHibernate.Util;
 using Remotion.Linq.Parsing.ExpressionVisitors.Transformation;
@@ -20,6 +21,7 @@ public class RemoveRedundantCast : IExpressionTransformer<UnaryExpression>
 		public Expression Transform(UnaryExpression expression)
 		{
 			if (expression.Type != typeof(object) &&
+				expression.Type != typeof(Enum) &&
 				expression.Type.IsAssignableFrom(expression.Operand.Type) &&
 				expression.Method == null &&
 				!expression.IsLiftedToNull)

src/NHibernate/Linq/Functions/DefaultLinqToHqlGeneratorsRegistry.cs

@@ -69,6 +69,7 @@ public DefaultLinqToHqlGeneratorsRegistry()
 			this.Merge(new DecimalNegateGenerator());
 			this.Merge(new RoundGenerator());
 			this.Merge(new TruncateGenerator());
+			this.Merge(new HasFlagGenerator());
 
 			var indexerGenerator = new ListIndexerGenerator();
 			RegisterGenerator(indexerGenerator);

src/NHibernate/Linq/Functions/HasFlagGenerator.cs

@@ -0,0 +1,30 @@
+using System;
+using System.Collections.ObjectModel;
+using System.Linq.Expressions;
+using System.Reflection;
+using NHibernate.Hql.Ast;
+using NHibernate.Linq.Visitors;
+using NHibernate.Util;
+
+namespace NHibernate.Linq.Functions
+{
+	internal class HasFlagGenerator : BaseHqlGeneratorForMethod
+	{
+		private const string _bitAndFunctionName = "band";
+
+		public HasFlagGenerator()
+		{
+			SupportedMethods = new[] { ReflectHelper.GetMethodDefinition<Enum>(x => x.HasFlag(default)) };
+		}
+
+		public override HqlTreeNode BuildHql(MethodInfo method, Expression targetObject, ReadOnlyCollection<Expression> arguments, HqlTreeBuilder treeBuilder, IHqlExpressionVisitor visitor)
+		{
+			return treeBuilder.Equality(
+						treeBuilder.MethodCall(
+							_bitAndFunctionName,
+							 visitor.Visit(targetObject).AsExpression(),
+							 visitor.Visit(arguments[0]).AsExpression()),
+						visitor.Visit(arguments[0]).AsExpression());
+		}
+	}
+}