System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.GetCastTargetType C# (CSharp) Method

        private TypeUsage GetCastTargetType(TypeUsage fromType, Type toClrType, Type fromClrType, bool preserveCastForDateTime)
        {
            // An IQueryable can report its type as ObjectQuery, IQueryable, or IOrderedQueryable depending on how the type and
            // expression tree were created. At this point in the translation, unwrapping of the DbQuery to ObjectQuery has already
            // happened and checking for something other than ObjectQuery has already been done. Therefore, from a CQT translation
            // perspective we can treat all these types as the same and this therefore becomes a no-op.
            if (fromClrType != null
                && fromClrType.IsGenericType()
                && toClrType.IsGenericType()
                && (fromClrType.GetGenericTypeDefinition() == typeof(ObjectQuery<>)
                    || fromClrType.GetGenericTypeDefinition() == typeof(IQueryable<>)
                    || fromClrType.GetGenericTypeDefinition() == typeof(IOrderedQueryable<>))
                && (toClrType.GetGenericTypeDefinition() == typeof(ObjectQuery<>)
                    || toClrType.GetGenericTypeDefinition() == typeof(IQueryable<>)
                    || toClrType.GetGenericTypeDefinition() == typeof(IOrderedQueryable<>))
                && fromClrType.GetGenericArguments()[0] == toClrType.GetGenericArguments()[0])
            {
                return null;
            }

            //ignore System.Enum
            if (fromClrType != null
                && TypeSystem.GetNonNullableType(fromClrType).IsEnum
                && toClrType == typeof(Enum))
            {
                return null;
            }

            // If the types are the same or the fromType is assignable to toType, return null
            // (indicating no cast is required)
            TypeUsage toType;
            if (TryGetValueLayerType(toClrType, out toType)
                && CanOmitCast(fromType, toType, preserveCastForDateTime))
            {
                return null;
            }

            // Check that the cast is supported and adjust the target type as necessary.
            toType = ValidateAndAdjustCastTypes(toType, fromType, toClrType, fromClrType);

            return toType;
        }