Efcore: Translation error using negative

[dotnetshadow]

Trying to sum a list of numbers and apply a negative value to it.
Seems like a translation issue?

Steps to reproduce

Summing up a list of rows in a transaction table
Basically I needed the negative value of a sum, it turns out it was actually giving me -180 instead of -220
Instead I did -1 * (1 * 200 + 20) and it gave the right result not sure why?

```c#
_db.Transactions.Select(x=> x.Type == MyEnum.Type1 ? -(price * units + bonus) : 0)
_db.Transactions.Select(x=> x.Type == MyEnum.Type1 ? -(1 * 200 + 20) : 0)

**Using a linq sample gives the correct values**
```c#
static void Main(string[] args)
        {
            var i = -(1 * 200 + 20);

            Console.WriteLine($"{i}");
        }

Further technical details

EF Core version: 2.1.4
Database Provider: Microsoft.EntityFrameworkCore.SqlServer
Operating system: Windows 10
IDE: Visual Studio 2017 15.8.9

[tuespetre]

@smitpatel @maumar it looks like in DefaultQuerySqlGenerator, VisitUnary visits ExpressionType.Negate by appending the hyphen and then visiting the operand. Probably needs to add parenthesis before and after visiting the operand.

[poke]

For what it’s worth, the in-memory database does not have this problem (which is why my own attempts to reproduce this failed 😅)

[dotnetshadow]

@poke @tuespetre Actually I just realised that I'm using Z.EntityFramework.Plus Future query feature which might have the issue. I have opened up an issue there in case it's their issue more than entity framework?

var transactionQuery = _context.Transactions.AsNoTracking().Where(x => x.Id == id)
                .DeferredSum(
                    x => x.TradeType == TradeType.Buy ? -(x.Units * x.Stock.StockPrice.Last + x.Brokerage) : x.TradeType == TradeType.Sell ? x.Units * x.Stock.StockPrice.Last - x.Brokerage : 0)
                .FutureValue<decimal>();

[poke]

No, I was able to reproduce the problem eventually with the SQLite provider.

[dotnetshadow]

@poke Ahh that's awesome news, cheers hopefully the EF team will get on top of this. Could be pretty critical for some apps

[smitpatel]

Probably this still exist in new pipeline. Also look for other operatorType in SqlUnary.

[jonlouie]

@smitpatel I would like to contribute to the EF Core project and believe this issue is a suitable entry point. I took a look and was able to verify that this issue still exists for SQL Server and SQLite. Is it currently up for grabs?