Re: Method overrides and covariant return types

> By experience, we know that people _will_ write implicit overriding,
> and expect it to work, even though the documentation shows that
> method implementations have a different form. 

IMO the language user doesn't benefit from having 2 different ways to
express explicit overriding - override keyword & yet another method
implementation form. Choose one - override keyword.


> The good part about it being a warning is that it leaves the 
> choice to the new user to first focus on other errors he might get.

The good part about it being a warning is that it isn't an error!

Overriding is the default behaviour, the liklihood is that the code is
doing the correct thing, and the compiler is signaling *no more* than
the possibility that something else may have been intended. 


As previously noted, the motivation for making overloading the default
in C# (instead of overriding) was performance. For version safety,
there are keywords to make both overloading and overriding explicit -
not using those keywords results in a warning message.

warning CS0108: The keyword new is required on 'B.doSomething()'
because it hides inherited member 'A.doSomething()'

warning CS0114: 'B.doSomething2()' hides inherited member
'A.doSomething2()'. To make the current member override that
implementation, add the override keyword. Otherwise add the new
keyword.


class A {
   public void doSomething(){}
   public virtual void doSomething2(){}
}
class B : A {
   public void doSomething(){}
   public void doSomething2(){}
}


class B2 : A {
   public new void doSomething(){}
   public override void doSomething2(){}
}



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