Merge branch 'pr-23-fix'

Author: alex-kulakov

Extensions/Xtensive.Orm.BulkOperations/Internals/SetOperation.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Linq.Expressions;
@@ -140,7 +140,7 @@ private void AddConstantValue(AddValueContext addContext)
     {
       SqlTableColumn column = SqlDml.TableColumn(addContext.Statement.Table, addContext.Field.Column.Name);
       SqlExpression value;
-      object constant = FastExpression.Lambda(addContext.Lambda.Body, null).Compile().DynamicInvoke();
+      object constant = FastExpression.Lambda(addContext.Lambda.Body).Compile().DynamicInvoke();
       if (constant==null)
         value = SqlDml.Null;
       else {

Orm/Xtensive.Orm/Linq/FastExpression.cs

@@ -26,19 +26,20 @@ public static class FastExpression
     /// <returns>Constructed lambda expression.</returns>
     public static LambdaExpression Lambda(Type delegateType, Expression body, params ParameterExpression[] parameters)
     {
-      return LambdaExpressionFactory.Instance.CreateLambda(delegateType, body, parameters);
+      return LambdaExpressionFactory.Instance.CreateLambda(delegateType, body, parameters ?? Array.Empty<ParameterExpression>());
     }
 
     /// <summary>
     /// Generates <see cref="LambdaExpression"/> faster than <see cref="Expression.Lambda(Type,Expression,ParameterExpression[])"/>.
     /// </summary>
-    /// <param name="delegateType">A type that represents a delegate type.</param>
+    /// <typeparam name="TDelegate">A type that represents a delegate type.</typeparam>
     /// <param name="body">The body of lambda expression.</param>
     /// <param name="parameters">The parameters of lambda expression.</param>
     /// <returns>Constructed lambda expression.</returns>
     public static Expression<TDelegate> Lambda<TDelegate>(Expression body, params ParameterExpression[] parameters)
     {
-      return (Expression<TDelegate>) LambdaExpressionFactory.Instance.CreateLambda(typeof(TDelegate), body, parameters);
+      return (Expression<TDelegate>) LambdaExpressionFactory.Instance
+        .CreateLambda(typeof(TDelegate), body, parameters ?? Array.Empty<ParameterExpression>());
     }
 
     /// <summary>
@@ -61,7 +62,7 @@ public static LambdaExpression Lambda(Type delegateType, Expression body, IEnume
     /// <returns>Constructed lambda expression.</returns>
     public static LambdaExpression Lambda(Expression body, params ParameterExpression[] parameters)
     {
-      return LambdaExpressionFactory.Instance.CreateLambda(body, parameters);
+      return LambdaExpressionFactory.Instance.CreateLambda(body, parameters ?? Array.Empty<ParameterExpression>());
     }
 
     /// <summary>