Fix parameter detection related to sequence selectors for Linq provider

src/NHibernate.Test/Async/Linq/ParameterTests.cs

@@ -142,6 +142,20 @@ public async Task UsingParameterInEvaluatableExpressionAsync()
 			await (db.Users.Where(x => names.Length == 0 || names.Contains(x.Name)).ToListAsync());
 		}
 
+		[Test]
+		public async Task UsingParameterOnSelectorsAsync()
+		{
+			var user = new User() {Id = 1};
+			await (db.Users.Where(o => o == user).ToListAsync());
+			await (db.Users.FirstOrDefaultAsync(o => o == user));
+			await (db.Timesheets.Where(o => o.Users.Any(u => u == user)).ToListAsync());
+
+			var users = new[] {new User() {Id = 1}};
+			await (db.Users.Where(o => users.Contains(o)).ToListAsync());
+			await (db.Users.FirstOrDefaultAsync(o => users.Contains(o)));
+			await (db.Timesheets.Where(o => o.Users.Any(u => users.Contains(u))).ToListAsync());
+		}
+
 		[Test]
 		public async Task UsingNegateValueTypeParameterTwiceAsync()
 		{

src/NHibernate.Test/Async/NHSpecificTest/GH2465/Fixture.cs

@@ -0,0 +1,100 @@
+//------------------------------------------------------------------------------
+// <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.GH2465
+{
+	using System.Threading.Tasks;
+	[TestFixture]
+	public class FixtureAsync : BugTestCase
+	{
+		protected override bool AppliesTo(Dialect.Dialect dialect)
+		{
+			return dialect.SupportsScalarSubSelects;
+		}
+
+		protected override void OnSetUp()
+		{
+			using (var session = OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				var applicant = new Entity {IdentityNames = {"name1", "name2"}};
+				session.Save(applicant);
+
+				transaction.Commit();
+			}
+		}
+
+		protected override void OnTearDown()
+		{
+			using (var session = OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				session.Delete("from System.Object");
+				transaction.Commit();
+			}
+		}
+
+		[Test]
+		public async Task ContainsInsideValueCollectionAsync()
+		{
+			using (var session = OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				var identityNames = new[] {"name1", "x"};
+				await (session
+					.Query<Entity>()
+					.Where(a => a.IdentityNames.Any(n => identityNames.Contains(n)))
+					.ToListAsync());
+				await (session
+					.Query<Entity>()
+					.Where(a => a.IdentityNames.All(n => identityNames.Contains(n)))
+					.ToListAsync());
+				await (session
+					.Query<Entity>()
+					.Where(a => a.IdentityNames.FirstOrDefault(n => identityNames.Contains(n)) == "test")
+					.ToListAsync());
+
+				await (transaction.CommitAsync());
+			}
+		}
+
+		[Test]
+		public async Task EqualsInsideValueCollectionAsync()
+		{
+			using (var session = OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				var value = "test";
+				await (session
+					.Query<Entity>()
+					.Where(a => a.IdentityNames.Any(n => n == value))
+					.ToListAsync());
+				await (session
+					.Query<Entity>()
+					.Where(a => a.IdentityNames.Any(n => (string) n == value))
+					.ToListAsync());
+				await (session
+					.Query<Entity>()
+					.Where(a => a.IdentityNames.All(n => n == value))
+					.ToListAsync());
+				await (session
+					.Query<Entity>()
+					.Where(a => a.IdentityNames.FirstOrDefault(n => n == "test") == "test")
+					.ToListAsync());
+
+				await (transaction.CommitAsync());
+			}
+		}
+	}
+}

src/NHibernate.Test/Linq/ParameterTests.cs

@@ -130,6 +130,20 @@ public void UsingParameterInEvaluatableExpression()
 			db.Users.Where(x => names.Length == 0 || names.Contains(x.Name)).ToList();
 		}
 
+		[Test]
+		public void UsingParameterOnSelectors()
+		{
+			var user = new User() {Id = 1};
+			db.Users.Where(o => o == user).ToList();
+			db.Users.FirstOrDefault(o => o == user);
+			db.Timesheets.Where(o => o.Users.Any(u => u == user)).ToList();
+
+			var users = new[] {new User() {Id = 1}};
+			db.Users.Where(o => users.Contains(o)).ToList();
+			db.Users.FirstOrDefault(o => users.Contains(o));
+			db.Timesheets.Where(o => o.Users.Any(u => users.Contains(u))).ToList();
+		}
+
 		[Test]
 		public void ValidateMixingTwoParametersCacheKeys()
 		{

src/NHibernate.Test/NHSpecificTest/GH2465/Entity.cs

@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+
+namespace NHibernate.Test.NHSpecificTest.GH2465
+{
+	public class Entity
+	{
+		private readonly IList<string> _identityNames = new List<string>();
+
+		public virtual Guid Id { get; set; }
+
+		public virtual IList<string> IdentityNames => _identityNames;
+	}
+}

src/NHibernate.Test/NHSpecificTest/GH2465/Fixture.cs

@@ -0,0 +1,88 @@
+using System.Linq;
+using NUnit.Framework;
+
+namespace NHibernate.Test.NHSpecificTest.GH2465
+{
+	[TestFixture]
+	public class Fixture : BugTestCase
+	{
+		protected override bool AppliesTo(Dialect.Dialect dialect)
+		{
+			return dialect.SupportsScalarSubSelects;
+		}
+
+		protected override void OnSetUp()
+		{
+			using (var session = OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				var applicant = new Entity {IdentityNames = {"name1", "name2"}};
+				session.Save(applicant);
+
+				transaction.Commit();
+			}
+		}
+
+		protected override void OnTearDown()
+		{
+			using (var session = OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				session.Delete("from System.Object");
+				transaction.Commit();
+			}
+		}
+
+		[Test]
+		public void ContainsInsideValueCollection()
+		{
+			using (var session = OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				var identityNames = new[] {"name1", "x"};
+				session
+					.Query<Entity>()
+					.Where(a => a.IdentityNames.Any(n => identityNames.Contains(n)))
+					.ToList();
+				session
+					.Query<Entity>()
+					.Where(a => a.IdentityNames.All(n => identityNames.Contains(n)))
+					.ToList();
+				session
+					.Query<Entity>()
+					.Where(a => a.IdentityNames.FirstOrDefault(n => identityNames.Contains(n)) == "test")
+					.ToList();
+
+				transaction.Commit();
+			}
+		}
+
+		[Test]
+		public void EqualsInsideValueCollection()
+		{
+			using (var session = OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				var value = "test";
+				session
+					.Query<Entity>()
+					.Where(a => a.IdentityNames.Any(n => n == value))
+					.ToList();
+				session
+					.Query<Entity>()
+					.Where(a => a.IdentityNames.Any(n => (string) n == value))
+					.ToList();
+				session
+					.Query<Entity>()
+					.Where(a => a.IdentityNames.All(n => n == value))
+					.ToList();
+				session
+					.Query<Entity>()
+					.Where(a => a.IdentityNames.FirstOrDefault(n => n == "test") == "test")
+					.ToList();
+
+				transaction.Commit();
+			}
+		}
+	}
+}

src/NHibernate.Test/NHSpecificTest/GH2465/Mappings.hbm.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="NHibernate.Test" namespace="NHibernate.Test.NHSpecificTest.GH2465">
+  <class name="Entity">
+    <id name="Id" generator="guid.comb"/>
+    <bag name="IdentityNames" access="nosetter.camelcase-underscore">
+      <key column="EntityId"/>
+      <element type="String">
+        <column name="IdentityName"/>
+      </element>
+    </bag>
+  </class>
+</hibernate-mapping>

src/NHibernate/Linq/Visitors/ParameterTypeLocator.cs

@@ -4,6 +4,7 @@
 using System.Linq.Expressions;
 using NHibernate.Engine;
 using NHibernate.Param;
+using NHibernate.Persister.Collection;
 using NHibernate.Type;
 using NHibernate.Util;
 using Remotion.Linq;
@@ -110,6 +111,12 @@ internal static void SetParameterTypes(
 							out _,
 							out _))
 						{
+							if (type.IsAssociationType && visitor.SequenceSelectorExpressions.Contains(memberExpression))
+							{
+								var collection = (IQueryableCollection) ((IAssociationType) type).GetAssociatedJoinable(sessionFactory);
+								type = collection.ElementType;
+							}
+
 							break;
 						}
 					}
@@ -137,6 +144,7 @@ private class ConstantTypeLocatorVisitor : RelinqExpressionVisitor
 				new Dictionary<ConstantExpression, IType>();
 			public readonly Dictionary<Expression, HashSet<Expression>> RelatedExpressions =
 				new Dictionary<Expression, HashSet<Expression>>();
+			public readonly HashSet<Expression> SequenceSelectorExpressions = new HashSet<Expression>();
 
 			public ConstantTypeLocatorVisitor(
 				bool removeMappedAsCalls,
@@ -247,6 +255,13 @@ querySourceReference.ReferencedQuerySource is MainFromClause mainFromClause &&
 				}
 				else
 				{
+					// In case a parameter is related to a sequence selector we will have to get the underlying item type
+					// (e.g. q.Where(o => o.Users.Any(u => u == user)))
+					if (node.QueryModel.ResultOperators.Any(o => o is ValueFromSequenceResultOperatorBase))
+					{
+						SequenceSelectorExpressions.Add(node.QueryModel.SelectClause.Selector);
+					}
+
 					node.QueryModel.TransformExpressions(Visit);
 				}