DateTime converted to Nullable<DateTime> inside optional navigation property, throws exception on AddDays

[nth-commit]

I believe this is a regression from RC1 or RC2 (I migrated from RC1 => RTM).

Trying to query all the orders completed within the last day:
(Note: Placement is the optional navigational property and, in the context of my solution, if it exists it indicates than the order has been placed)

var ordersCompleted = await dbContext.Orders
                .Where(o => o.IsCompleted)
                .Where(o => o.Error == OrderErrorType.None)
                .Where(o => o.Placement.Placed.AddDays(1) > now)
                .ToListAsync();

Exception:

Message: Method 'System.DateTime AddDays(Double)' declared on type 'System.DateTime' cannot be called with instance of type 'System.Nullable`1[System.DateTime]'

StackTrace: 
   at System.Linq.Expressions.Expression.ValidateCallInstanceType(Type instanceType, MethodInfo method)
   at System.Linq.Expressions.Expression.ValidateStaticOrInstanceMethod(Expression instance, MethodInfo method)
   at System.Linq.Expressions.Expression.Call(Expression instance, MethodInfo method, IEnumerable`1 arguments)
   at Microsoft.EntityFrameworkCore.Query.ExpressionVisitors.Internal.NavigationRewritingExpressionVisitor.VisitMethodCall(MethodCallExpression node)
   at Microsoft.EntityFrameworkCore.Query.ExpressionVisitors.Internal.NavigationRewritingExpressionVisitor.VisitBinary(BinaryExpression node)
   at Remotion.Linq.Clauses.WhereClause.TransformExpressions(Func`2 transformation)
   at Remotion.Linq.QueryModelVisitorBase.VisitBodyClauses(ObservableCollection`1 bodyClauses, QueryModel queryModel)
   at Remotion.Linq.QueryModelVisitorBase.VisitQueryModel(QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Query.ExpressionVisitors.Internal.NavigationRewritingExpressionVisitor.Rewrite(QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.OptimizeQueryModel(QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.CreateAsyncQueryExecutor[TResult](QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddAsyncQuery[TResult](Object cacheKey, Func`1 compiler)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.ExecuteAsync[TResult](Expression query)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable`1.System.Collections.Generic.IAsyncEnumerable<TResult>.GetEnumerator()
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.<ToListAsync>d__129`1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at VegeRun.Services.Orders.Queries.OrderQueries.<GetLiveOrdersAsync>d__3.MoveNext() in C:\Users\Michael\Code\Personal\20160429\VegeRun\src\VegeRun.Services\Orders\Queries\OrderQueries.cs:line 155

Relevant classes (minimalized):

public class Order
{
public Guid Id { get; set; }

public bool IsCompleted { get; set; }

public OrderErrorType Error { get; set; }

public Guid? PlacementId { get; set; }

public virtual OrderPlacement Placement { get; set; }
}

public class OrderPlacement
{
public Guid Id { get; set; }

public DateTime Placed { get; set; }
}

Workaround:

var ordersCompleted2 = (await dbContext.Orders
                .Where(o => o.IsCompleted)
                .Where(o => o.Error == OrderErrorType.None)
                .Join(
                    dbContext.OrderPlacements,
                    o => o.PlacementId,
                    p => p.Id,
                    (o, p) => new { Order = o, Placement = p })
                .Where(op => op.Placement.Placed.AddDays(1) > now)
                .ToListAsync()).Select(op => op.Order);

[divega]

@maumar we belive this is happening because the nav prop is rewritten and the type becomes nullable.

[maumar]

Related to #5613

[maumar]

fixed in 7472a67