Fix caching SQL queries with enabled auto discovery type

src/NHibernate.Test/Async/SqlTest/Query/NativeSQLQueriesFixture.cs

@@ -216,6 +216,72 @@ public async Task SQLQueryInterfaceCacheableAsync()
 			}
 		}
 
+		[Test(Description = "GH-2904")]
+		public async Task CacheableScalarSQLQueryAsync()
+		{
+			Organization ifa = new Organization("IFA");
+			Organization jboss = new Organization("JBoss");
+			Person gavin = new Person("Gavin");
+			Employment emp = new Employment(gavin, jboss, "AU");
+
+			using (ISession s = OpenSession())
+			using (ITransaction t = s.BeginTransaction())
+			{
+				await (s.SaveAsync(ifa));
+				await (s.SaveAsync(jboss));
+				await (s.SaveAsync(gavin));
+				await (s.SaveAsync(emp));
+				await (t.CommitAsync());
+			}
+
+			using (ISession s = OpenSession())
+			{
+				Task<IList> GetCacheableSqlQueryResultsAsync()
+				{
+				try
+				{
+						return s.CreateSQLQuery(
+									"select emp.REGIONCODE " +
+									"from ORGANIZATION org " +
+									"left outer join EMPLOYMENT emp on org.ORGID = emp.EMPLOYER ")
+								.AddScalar("regionCode", NHibernateUtil.String)
+								.SetCacheable(true)
+								.ListAsync();
+					}
+				catch (System.Exception ex)
+				{
+					return Task.FromException<IList>(ex);
+				}
+			}
+
+				using (EnableStatisticsScope())
+				{
+					IList l = await (GetCacheableSqlQueryResultsAsync());
+					Assert.AreEqual(2, l.Count);
+					Assert.That(Sfi.Statistics.QueryCacheMissCount, Is.EqualTo(1), "results are expected from DB");
+					Assert.That(Sfi.Statistics.QueryCacheHitCount, Is.EqualTo(0), "results are expected from DB");
+				}
+
+				using (EnableStatisticsScope())
+				{
+					IList l2 = await (GetCacheableSqlQueryResultsAsync());
+					Assert.AreEqual(2, l2.Count);
+					Assert.That(Sfi.Statistics.QueryCacheMissCount, Is.EqualTo(0), "results are expected from cache");
+					Assert.That(Sfi.Statistics.QueryCacheHitCount, Is.EqualTo(1), "results are expected from cache");
+				}
+			}
+
+			using (var s = OpenSession())
+			using (var t = s.BeginTransaction())
+			{
+				await (s.DeleteAsync(emp));
+				await (s.DeleteAsync(gavin));
+				await (s.DeleteAsync(ifa));
+				await (s.DeleteAsync(jboss));
+				await (t.CommitAsync());
+			}
+		}
+
 		[Test]
 		public async Task ResultSetMappingDefinitionAsync()
 		{

src/NHibernate.Test/SqlTest/Query/NativeSQLQueriesFixture.cs

@@ -205,6 +205,65 @@ public void SQLQueryInterfaceCacheable()
 			}
 		}
 
+		[Test(Description = "GH-2904")]
+		public void CacheableScalarSQLQuery()
+		{
+			Organization ifa = new Organization("IFA");
+			Organization jboss = new Organization("JBoss");
+			Person gavin = new Person("Gavin");
+			Employment emp = new Employment(gavin, jboss, "AU");
+
+			using (ISession s = OpenSession())
+			using (ITransaction t = s.BeginTransaction())
+			{
+				s.Save(ifa);
+				s.Save(jboss);
+				s.Save(gavin);
+				s.Save(emp);
+				t.Commit();
+			}
+
+			using (ISession s = OpenSession())
+			{
+				IList GetCacheableSqlQueryResults()
+				{
+					return s.CreateSQLQuery(
+								"select emp.REGIONCODE " +
+								"from ORGANIZATION org " +
+								"left outer join EMPLOYMENT emp on org.ORGID = emp.EMPLOYER ")
+							.AddScalar("regionCode", NHibernateUtil.String)
+							.SetCacheable(true)
+							.List();
+				}
+
+				using (EnableStatisticsScope())
+				{
+					IList l = GetCacheableSqlQueryResults();
+					Assert.AreEqual(2, l.Count);
+					Assert.That(Sfi.Statistics.QueryCacheMissCount, Is.EqualTo(1), "results are expected from DB");
+					Assert.That(Sfi.Statistics.QueryCacheHitCount, Is.EqualTo(0), "results are expected from DB");
+				}
+
+				using (EnableStatisticsScope())
+				{
+					IList l2 = GetCacheableSqlQueryResults();
+					Assert.AreEqual(2, l2.Count);
+					Assert.That(Sfi.Statistics.QueryCacheMissCount, Is.EqualTo(0), "results are expected from cache");
+					Assert.That(Sfi.Statistics.QueryCacheHitCount, Is.EqualTo(1), "results are expected from cache");
+				}
+			}
+
+			using (var s = OpenSession())
+			using (var t = s.BeginTransaction())
+			{
+				s.Delete(emp);
+				s.Delete(gavin);
+				s.Delete(ifa);
+				s.Delete(jboss);
+				t.Commit();
+			}
+		}
+
 		[Test]
 		public void ResultSetMappingDefinition()
 		{

src/NHibernate.Test/TestCase.cs

@@ -389,6 +389,11 @@ protected virtual ISession OpenSession()
 			return Sfi.OpenSession();
 		}
 
+		protected virtual IDisposable EnableStatisticsScope()
+		{
+			return new StatisticsScope(Sfi);
+		}
+
 		protected virtual ISession OpenSession(IInterceptor sessionLocalInterceptor)
 		{
 			return Sfi.WithOptions().Interceptor(sessionLocalInterceptor).OpenSession();
@@ -574,6 +579,24 @@ public void Dispose()
 			}
 		}
 
+		protected class StatisticsScope : IDisposable
+		{
+			private readonly ISessionFactoryImplementor _factory;
+
+			public StatisticsScope(ISessionFactoryImplementor factory)
+			{
+				_factory = factory;
+				_factory.Statistics.IsStatisticsEnabled = true;
+				_factory.Statistics.Clear();
+			}
+
+			public void Dispose()
+			{
+				_factory.Statistics.IsStatisticsEnabled = false;
+				_factory.Statistics.Clear();
+			}
+		}
+
 		#endregion
 	}
 }

src/NHibernate/Transform/CacheableResultTransformer.cs

@@ -387,7 +387,7 @@ public override bool Equals(object o)
 
 			// Auto-discovery does not allow distinguishing by transformer: just compare their queries
 			if (AutoDiscoverTypes && that.AutoDiscoverTypes)
-				return _autoDiscoveredQuery == that._autoDiscoveredQuery;
+				return Equals(_autoDiscoveredQuery, that._autoDiscoveredQuery);
 
 			return HasSameParameters(that);
 		}