After upgrading from NET8 to NET10, Dynamic Linq "in" statement return different results in Debug or Release mode

[hcd]

Hi,

After upgrading our application fron .NET 8.0 to .NET 10.0, we got reports that our queries don’t return the correct number of entities anymore.

We’ve investigated and could pinpoint and extract the following case which demonstrates the broken behavior.

Consider the following simple code for a console app :

using System.Linq.Dynamic.Core;
 
namespace DynamicLinq
{
    internal class Program
    {
        static void Main(string[] args)
        {
            var list = new List<MyEntity>();
            for (int i = 0; i < 10000; i++)
                list.Add(new MyEntity{Id= i});                
 
 
            var test1 = list.AsQueryable()
                .Where("Id in (9495, 9496, 9498, 9500, 9501, 9503, 9505, 9508, 9509, 9510, 9511, 9514, 9515, 9517, 9518, 9519, 9520, 9521, 9523, 9524, 9525, 9526, 9527, 9528, 9529, 9530, 9531, 9532, 9533, 9534, 9535, 9536, 9538, 9539, 9540, 9541, 9542, 9543, 9544, 9545, 9546, 9547, 9548, 9549, 9550, 9552, 9554, 9556, 9557, 9558, 9559, 9560, 9561, 9562, 9563, 9565, 9567, 9569, 9570, 9575, 9576, 9577, 9578, 9579, 9580, 9581, 9582, 9583, 9584, 9585, 9586, 9587, 9588, 9589, 9590, 9591, 9592, 9593, 9594, 9595, 9596, 9597, 9598, 9599, 9600, 9601, 9602, 9603, 9604, 9605, 9606, 9607, 9608, 9609, 9610, 9611, 9612, 9613, 9614, 9615, 9616, 9617, 9618, 9619, 9620, 9621, 9622, 9623, 9624, 9625, 9626, 9627, 9628, 9629)")
                .ToList();
 
            Console.WriteLine("Number of elements : " + test1.Count);  //should be 114 elements – but shows 64 when running in Release mode
        }
    }
 
    class MyEntity
    {
        public int Id { get; set; }
    }
}

When running this in Debug mode, it correctly shows correctly 114 elements. When running it in Release mode , it shows 64 elements

Also, this only happens in .NET 10.0 ...
When downgrading the console app to .NET 8.0 , both release and debug mode show 114 elements.

We consider this a quite serious bug, because it breaks things in our application and we see no workaround for it, except downgrading back to NET 8.0 (which would be a LOT of work …)

Kind regards,
Sven.

[hcd]

I've expanded a little the code, trying to figure out how this can happen ?

ended up with this :

using System.Linq.Dynamic.Core;

namespace DynamicLinq
{
    internal class Program
    {
        static void Main(string[] args)
        {
            //the list of ids that were actually used in our application and resulted in the discovery of this bug
            var originalIdList = new List<int>() { 9495, 9496, 9498, 9500, 9501, 9503, 9505, 9508, 9509, 9510, 9511, 9514, 9515, 9517, 9518, 9519, 9520, 9521, 9523, 9524, 9525, 9526, 9527, 9528, 9529, 9530, 9531, 9532, 9533, 9534, 9535, 9536, 9538, 9539, 9540, 9541, 9542, 9543, 9544, 9545, 9546, 9547, 9548, 9549, 9550, 9552, 9554, 9556, 9557, 9558, 9559, 9560, 9561, 9562, 9563, 9565, 9567, 9569, 9570, 9575, 9576, 9577, 9578, 9579, 9580, 9581, 9582, 9583, 9584, 9585, 9586, 9587, 9588, 9589, 9590, 9591, 9592, 9593, 9594, 9595, 9596, 9597, 9598, 9599, 9600, 9601, 9602, 9603, 9604, 9605, 9606, 9607, 9608, 9609, 9610, 9611, 9612, 9613, 9614, 9615, 9616, 9617, 9618, 9619, 9620, 9621, 9622, 9623, 9624, 9625, 9626, 9627, 9628, 9629};
            //list of ids also starting at 9495, but without gaps
            var adjacentIdList = Enumerable.Range(9495, 114);
            //original list starting at Id1
            var originalIdListStartingAt1 = originalIdList.Select(id => id - 9494);
            //list with gaps of 1
            var listWithGapsOf1 = Enumerable.Range(1, 114).Select(id => id * 2);
            //list with gaps of 2
            var listWithGapsOf2 = Enumerable.Range(1, 114).Select(id => id * 3);
            //list with gaps of 3
            var listWithGapsOf3 = Enumerable.Range(1, 114).Select(id => id * 4);
            //list with gaps of 4
            var listWithGapsOf4 = Enumerable.Range(1, 114).Select(id => id * 5);

            //list of 10.000 entities , with ids starting at 0
            var entityList = MyEntity.CreateList(Enumerable.Range(1, 10_000));

            Filter(entityList, originalIdList);
            Filter(entityList, adjacentIdList);
            Filter(entityList, originalIdListStartingAt1);
            Filter(entityList, listWithGapsOf1);
            Filter(entityList, listWithGapsOf2);
            Filter(entityList, listWithGapsOf3);
            Filter(entityList, listWithGapsOf4);
        }

        //filter the list of entities by the list of ids using dynamic linq and write the number of elements in the filtered list to the console
        static void Filter(IEnumerable<MyEntity> entities, IEnumerable<int> ids)
        {
            var filtered = entities.AsQueryable().Where($"Id in ({String.Join(',', ids)})").ToList();
            Console.WriteLine("Number of elements : " + filtered.Count);
        }

    }

    class MyEntity
    {
        //factory method to create a list of MyEntity objects from a given list of ids
        public static IEnumerable<MyEntity> CreateList(IEnumerable<int> ids)
        {
            foreach (var id in ids) yield return new MyEntity { Id = id };
        }

        public int Id { get; set; }
    }
}

Running this in .NET 10 Debug (or NET 8 debug/release) mode gives :

Number of elements : 114
Number of elements : 114
Number of elements : 114
Number of elements : 114
Number of elements : 114
Number of elements : 114
Number of elements : 114

which is correct.
Running it in .NET 10 Release mode gives :

Number of elements : 64
Number of elements : 114
Number of elements : 64
Number of elements : 114
Number of elements : 114
Number of elements : 114
Number of elements : 114

Also, when chunking the original idList in 2 lists, and use the Dynamic Linq query "where id in chunk1 OR id in chunk2" then it is also correct ....

Kind regards,
Sven.

[StefH]

I am looking into this.

[StefH]

@hcd
Can you please test 1.7.4-preview-01?

[StefH]

#988

[hcd]

Yes ! That seems to do the trick 👍👍

[StefH]

@hcd
Good to hear.
I'll release new normal NuGet version today.