'out' can be ommited in overrides, causing silent bugs.

[Accensus]

Take this code for example:

Code: Select all • Expand view

class BaseClass abstract
{
   abstract void F1(out int ticker);
   abstract void F2(out int ticker);
}

class DerivedClass : BaseClass
{
   override void F1(out int ticker)
   {
      Console.Printf("F1: %i", ticker);
   }
   override void F2(int ticker)
   {
      Console.Printf("F2: %i", ticker);
   }
}

class OutParamTest : Actor
{
   override void BeginPlay()
   {
      Super.BeginPlay();
      cls = new('DerivedClass');
   }
   override void Tick()
   {
      cls.F1(Ticker);
      cls.F2(Ticker);
      Ticker++;

      Super.Tick();
   }

   int Ticker;
   BaseClass cls;
}

This results in F1 printing the correct number: 0, 1, 2, 3 and so on, but F2 prints out some 10 digit negative number.

I had this happen in some code elsewhere and had to spend some good 20 minutes to figure out where the problem was exactly. Shouldn't this be a warning at the very least? This also sounds like a possible security concern.

[Marisa the Magician]

Rather than a warning this should be an error outright if it causes issues like those.

Especially because warnings tend to get largely ignored by most modders.

[Accensus]

Wouldn't that break existing mods? Unless it only errors past a certain version, but I don't know how possible that'd be for something like this.

[Marisa the Magician]

Sometimes you have to risk breakage to fix such a huge oversight, especially because this appears to be causing undefined behavior.

[nova++]

Yeah, it sounds like this is enough of an issue that breaking stuff that might be using/abusing it would be a good thing.