Linq to EF Join throws “Index was out of range” after upgrade from VS2010 to VS2012

Question

After upgrading from Visual Studio 2010 to 2012 code started throwing \"ArgumentOutOfRangeException - Index was out of range. Must be non-negative and less than the size of the

Answer 1

After giving this some more investigation, I've come to the conclusion that the problem is the anonymous class I'm returning from the Linq query, I think it isn't allowed anymore to return an anonymous class with only one field in it, I know it isn't needed to wrap the field in an anonymous class but ... as I said this worked before upgrading.

Following example gives me the "ArgumentOutOfRangeException - Index was out of range":

void Main()
{
    var iq1 = ActionPlans.Select(ap => ap.ID).ToList();
    var iq2 = iq1.Join(ActionPlans.Select(ap => ap.ID),
                    a => a,
                    b => b,
                    (a, b) => new { a });

    iq2.Dump();
}

this next example works as expected:

void Main()
{
    var iq1 = ActionPlans.Select(ap => ap.ID).ToList();
    var iq2 = iq1.Join(ActionPlans.Select(ap => ap.ID),
                    a => a,
                    b => b,
                    (a, b) => a );

    iq2.Dump();
}

Answer 2

Erwin, just to close the loop on this: We have confirmed that it is a bug we introduced recently in LINQ to Entities and we are looking at ways to get a fix out. Thanks a lot for reporting it!