ArgumentException: The given expression '([o] As Bar)' does not contain the searched expression '[o]'

[myrup]

Getting an ArgumentException when attempting to list contents of a DbSet as a subclassed List.

Exception message: 

ArgumentException: The given expression '([o] As Bar)' does not contain the searched expression '[o]' in a nested NewExpression with member assignments or a MemberBindingExpression.
Parameter name: fullExpression

Stack trace:

System.RuntimeMethodHandle.InvokeMethod(object target, object[] arguments, Signature sig, bool constructor, bool wrapExceptions)
System.Reflection.RuntimeMethodInfo.Invoke(object obj, BindingFlags invokeAttr, Binder binder, object[] parameters, CultureInfo culture)
Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.TrackEntitiesInResults<TResult>(QueryModel queryModel)
Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.CreateQueryExecutor<TResult>(QueryModel queryModel)
Microsoft.EntityFrameworkCore.Storage.Database.CompileQuery<TResult>(QueryModel queryModel)
Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore<TResult>(Expression query, IQueryModelGenerator queryModelGenerator, IDatabase database, IDiagnosticsLogger<Query> logger, Type contextType)
Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler+<>c__DisplayClass13_0<TResult>.<Execute>b__0()
Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQueryCore<TFunc>(object cacheKey, Func<Func<QueryContext, TFunc>> compiler)
Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQuery<TResult>(object cacheKey, Func<Func<QueryContext, TResult>> compiler)
Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.Execute<TResult>(Expression query)
Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.Execute<TResult>(Expression expression)
Remotion.Linq.QueryableBase<T>.GetEnumerator()
System.Collections.Generic.List<T>.AddEnumerable(IEnumerable<T> enumerable)
System.Linq.Enumerable.ToList<TSource>(IEnumerable<TSource> source)

Steps to reproduce

class Foo : Bar {
}
class Bar {
}

context.Foos.Select(b => b as Bar).ToList();

(context is a DbContext with a DbSet<Foo> Fooson it)

Further technical details

EF Core version: 2.1.1
Database Provider: Npgsql.EntityFrameworkCore.PostgreSQL
Operating system: OS X 10.13.5
IDE: Visual Studio Community 7.5.3

[myrup]

Forgot to mention context.Foos.ToList().Select(b => b as Bar).ToList(); gives the desired result.

[maumar]

Full repro:

    class Program
    {
        static void Main(string[] args)
        {
            using (var ctx = new MyContext())
            {
                ctx.Database.EnsureDeleted();
                ctx.Database.EnsureCreated();

                var f = new Foo();
                ctx.Foos.AddRange(f);
                ctx.SaveChanges();
            }

            using (var ctx = new MyContext())
            {
                var query1 = ctx.Foos.Select(b => (Bar)b).ToList(); // this works
                var query2 = ctx.Foos.Select(b => b as Bar).ToList(); // this fails

            }
        }
    }

    public class MyContext : DbContext
    {
        public DbSet<Foo> Foos { get; set; }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<Bar>();
        }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder.UseSqlServer(@"Server=.;Database=Repro12741;Trusted_Connection=True;MultipleActiveResultSets=True");
        }
    }

    public class Foo : Bar
    {
    }
    public class Bar
    {
        public int Id { get; set; }
    }

[maumar]

This is because relinq's AccessorFindingExpressionVisitor doesn't properly handle TypAs expression. Workaround is to use hard cast instead (shown in repro code above).

Filed a bug on relinq to track this: https://www.re-motion.org/jira/browse/RMLNQ-124

[maumar]

verified this issue has been fixed in 3.0