LINQKit does not support referencing expressions stored in properties (InvalidCastException)

[poizan42]

Running the following program:

using System;
using System.Linq.Expressions;
using LinqKit;

namespace Test
{
    class Program
    {
        public static Expression<Func<int, int>> Foo => x => x * 6;

        static void Main(string[] args)
        {
            Expression<Func<int, int>> bar = x => Foo.Invoke(x * 7);
            Expression<Func<int, int>> barExpanded = bar.Expand(); // <-- System.InvalidCastException
            Console.WriteLine(barExpanded.Invoke(1));
        }
    }
}

Fails with

System.InvalidCastException: Unable to cast object of type 'System.Linq.Expressions.PropertyExpression' to type 'System.Linq.Expressions.LambdaExpression'.
   at LinqKit.ExpressionExpander.VisitMethodCall(MethodCallExpression m) in C:\projects\LINQKit\src\LinqKit.Core\ExpressionExpander.cs:line 78
   at LinqKit.ExpressionVisitor.Visit(Expression exp) in C:\projects\LINQKit\src\LinqKit.Core\ExpressionVisitor.cs:line 71
   at LinqKit.ExpressionVisitor.VisitLambda(LambdaExpression lambda) in C:\projects\LINQKit\src\LinqKit.Core\ExpressionVisitor.cs:line 353
   at LinqKit.ExpressionVisitor.Visit(Expression exp) in C:\projects\LINQKit\src\LinqKit.Core\ExpressionVisitor.cs:line 73
   at LinqKit.Extensions.Expand[TDelegate](Expression`1 expr) in C:\projects\LINQKit\src\LinqKit.Core\Extensions.cs:line 54
   at Test.Program.Main(String[] args) in C:\projects\LINQKit\Test\Program.cs:line 14

This may be related to #89 where it's a delegate rather than an expression in a property that causes problems.

[sdanyliv]

@StefH, I think It should be fixed in #126

[StefH]

Hello @sdanyliv, thanks for noticing.

If you have time, can you add an extra UnitTest for this scenario? If this is green, then I can close this issue.

[StefH]

@poizan42 : Can you please try 1.1.20-preview-01 version in NuGet to see if this fixes your issue?

[poizan42]

It fixes the case I wrote in this issues. But it does not work with deeper nesting, e.g. the test ExpressionCombiner_ExpressionAsProperty_FromExpressionVariable still fails.

[sdanyliv]

Updated PR #127 with fix.

[StefH]

PR is merged.