Fix registration of current_date for some dialects

Also fix current_time for ASE 15 which looks like a bad copy-paste,
since this database has the exact matching function.

Author: fredericDelaporte

src/NHibernate.Test/Async/Hql/HQLFunctions.cs

@@ -1058,6 +1058,53 @@ public async Task Current_TimeStamp_OffsetAsync()
 			}
 		}
 
+		[Test]
+		public async Task Current_DateAsync()
+		{
+			AssumeFunctionSupported("current_date");
+			using (var s = OpenSession())
+			{
+				var a1 = new Animal("abcdef", 1.3f);
+				await (s.SaveAsync(a1));
+				await (s.FlushAsync());
+			}
+			using (var s = OpenSession())
+			{
+				var hql = "select current_date() from Animal";
+				await (s.CreateQuery(hql).ListAsync());
+			}
+		}
+
+		[Test]
+		public async Task Current_Date_IsLowestTimeOfDayAsync()
+		{
+			AssumeFunctionSupported("current_date");
+			var now = DateTime.Now;
+			if (!TestDialect.SupportsNonDataBoundCondition)
+				Assert.Ignore("Test is not supported by the target database");
+			if (now.TimeOfDay < TimeSpan.FromMinutes(5) || now.TimeOfDay > TimeSpan.Parse("23:55"))
+				Assert.Ignore("Test is unreliable around midnight");
+
+			var lowTimeDate = now.Date.AddSeconds(1);
+
+			using (var s = OpenSession())
+			{
+				var a1 = new Animal("abcdef", 1.3f);
+				await (s.SaveAsync(a1));
+				await (s.FlushAsync());
+			}
+			using (var s = OpenSession())
+			{
+				var hql = "from Animal where current_date() < :lowTimeDate";
+				var result =
+					await (s
+						.CreateQuery(hql)
+						.SetDateTime("lowTimeDate", lowTimeDate)
+						.ListAsync());
+				Assert.That(result, Has.Count.GreaterThan(0));
+			}
+		}
+
 		[Test]
 		public async Task ExtractAsync()
 		{

src/NHibernate.Test/Hql/HQLFunctions.cs

@@ -1047,6 +1047,53 @@ public void Current_TimeStamp_Offset()
 			}
 		}
 
+		[Test]
+		public void Current_Date()
+		{
+			AssumeFunctionSupported("current_date");
+			using (var s = OpenSession())
+			{
+				var a1 = new Animal("abcdef", 1.3f);
+				s.Save(a1);
+				s.Flush();
+			}
+			using (var s = OpenSession())
+			{
+				var hql = "select current_date() from Animal";
+				s.CreateQuery(hql).List();
+			}
+		}
+
+		[Test]
+		public void Current_Date_IsLowestTimeOfDay()
+		{
+			AssumeFunctionSupported("current_date");
+			if (!TestDialect.SupportsNonDataBoundCondition)
+				Assert.Ignore("Test is not supported by the target database");
+			var now = DateTime.Now;
+			if (now.TimeOfDay < TimeSpan.FromMinutes(5) || now.TimeOfDay > TimeSpan.Parse("23:55"))
+				Assert.Ignore("Test is unreliable around midnight");
+
+			var lowTimeDate = now.Date.AddSeconds(1);
+
+			using (var s = OpenSession())
+			{
+				var a1 = new Animal("abcdef", 1.3f);
+				s.Save(a1);
+				s.Flush();
+			}
+			using (var s = OpenSession())
+			{
+				var hql = "from Animal where current_date() < :lowTimeDate";
+				var result =
+					s
+						.CreateQuery(hql)
+						.SetDateTime("lowTimeDate", lowTimeDate)
+						.List();
+				Assert.That(result, Has.Count.GreaterThan(0));
+			}
+		}
+
 		[Test]
 		public void Extract()
 		{

src/NHibernate/Dialect/Oracle8iDialect.cs

@@ -250,7 +250,9 @@ protected virtual void RegisterFunctions()
 			RegisterFunction("to_char", new StandardSQLFunction("to_char", NHibernateUtil.String));
 			RegisterFunction("to_date", new StandardSQLFunction("to_date", NHibernateUtil.DateTime));
 
-			RegisterFunction("current_date", new NoArgSQLFunction("current_date", NHibernateUtil.Date, false));
+			// In Oracle, date includes a time, just with fractional seconds dropped. For actually only having
+			// the date, it must be truncated. Otherwise comparisons may yield unexpected results.
+			RegisterFunction("current_date", new SQLFunctionTemplate(NHibernateUtil.Date, "trunc(current_date)"));
 			RegisterFunction("current_time", new NoArgSQLFunction("current_timestamp", NHibernateUtil.Time, false));
 			RegisterFunction("current_timestamp", new CurrentTimeStamp());
 

src/NHibernate/Dialect/SybaseASE15Dialect.cs

@@ -68,8 +68,8 @@ public SybaseASE15Dialect()
 			RegisterFunction("concat", new VarArgsSQLFunction(NHibernateUtil.String, "(","+",")"));
 			RegisterFunction("cos", new StandardSQLFunction("cos", NHibernateUtil.Double));
 			RegisterFunction("cot", new StandardSQLFunction("cot", NHibernateUtil.Double));
-			RegisterFunction("current_date", new NoArgSQLFunction("getdate", NHibernateUtil.Date));
-			RegisterFunction("current_time", new NoArgSQLFunction("getdate", NHibernateUtil.Time));
+			RegisterFunction("current_date", new NoArgSQLFunction("current_date", NHibernateUtil.Date));
+			RegisterFunction("current_time", new NoArgSQLFunction("current_time", NHibernateUtil.Time));
 			RegisterFunction("current_timestamp", new NoArgSQLFunction("getdate", NHibernateUtil.DateTime));
 			RegisterFunction("datename", new StandardSQLFunction("datename", NHibernateUtil.String));
 			RegisterFunction("day", new StandardSQLFunction("day", NHibernateUtil.Int32));

src/NHibernate/Dialect/SybaseSQLAnywhere10Dialect.cs

@@ -232,7 +232,7 @@ protected virtual void RegisterDateFunctions()
 			// compatibility functions
 			RegisterFunction("current_timestamp", new NoArgSQLFunction("getdate", NHibernateUtil.DateTime, true));
 			RegisterFunction("current_time", new NoArgSQLFunction("getdate", NHibernateUtil.Time, true));
-			RegisterFunction("current_date", new NoArgSQLFunction("getdate", NHibernateUtil.Date, true));
+			RegisterFunction("current_date", new SQLFunctionTemplate(NHibernateUtil.Date, "date(getdate())"));
 		}
 
 		protected virtual void RegisterStringFunctions()