Implement support for Queryable.Cast

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Create a query that contains a cast, and run it

    Edu.EventStaff newEventStaff = new Edu.EventStaff();
    newEventStaff.Staff = (from Edu.Staff staffMember
        in EduDContext.Staff
        where staffMember.ContactID == (int)currentBooking.EduContactID
        select staffMember
    ).Single();

See also: 
http://groups.google.com/group/dblinq/browse_thread/thread/855c6fb79bc30616

What is the expected output? What do you see instead?
Expected output is no exception (or a reasonable exception if there is no 
data).

Actual output is: S0133: Implement QueryMethod Queryable.Cast.

Original issue reported on code.google.com by jonmpr...@gmail.com on 11 Mar 2010 at 1:33

[GoogleCodeExporter]

I was not able to reproduce using the northwind database and this query:

object empId = 1;
var et = new EmployeeTerritories();
et.Employees = (from e in nwind.Employees
                where e.ReportsTo == (int)empId
                select e).Single();

So there seems to be a bit more to it.

Original comment by anders...@gmail.com on 14 Mar 2010 at 12:42

[GoogleCodeExporter]

As per http://groups.google.com/group/dblinq/msg/5663128659a64096, it looks 
like the 
problem is that a type is declared in the 'from' expression:

    from Edu.Staff staffMember in EduDContext.Staff ...
         ^^^^^^^^^^^^^^^^^^^^^

as opposed to the more "normal"

    from staffMember in EduDContext.Staff ...
         ^^^^^^^^^^^

Original comment by jonmpr...@gmail.com on 15 Mar 2010 at 8:35

[GoogleCodeExporter]

Please, try out the solution on the link below:
http://code.google.com/p/dblinq2007/issues/detail?id=132#c2

Original comment by tos.oliv...@gmail.com on 1 Apr 2012 at 1:20