gcc-4.0-virtual function return type

[JFanatiker <jfanatiker at yahoo dot de>]

Hi!

I read the current changes of gcc-4.0. There is the following in the C++ part:

G++ has an undocumented extension to virtual function covariance rules that 
allowed the overrider to return a type that was implicitly convertable to the 
overridden function's return type. For instance a function returning void * 
could be overridden by a function returning T *. This is now deprecated and 
will be removed in a future release.

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Why are you going to throw away such good features like this one? This feature 
is something greatly extending the object oriented programming. - A method of 
a derived class can return a more specialised type as its parent- thats what 
oop is all about!: Specialisation of a base class. (This greatly extends 
polymorphism- very, very usefull!) 

I'm thinking very much about an "Ideal programming language", I also thought 
about this feature and considered it very good- now I read I can use this 
with g++, but it is going to be removed- appalling.

Is it only because this feature isn't specified in the ISO standard?
Then I would consider the following solutions better:
 - Suggest such good things to the iso committee 
 - Let extra features be only available with a compiler switch like 
--enable-gnu-c++-extensions
   or something like that, so that users can use them if they want- knowing 
   that this can cause portability problems.
   With this switch available, there would be no boundaries! Every good idea 
   could be implemented. (Standards are good, but cumbersome)


I know that standards are very important, but if a developer knows he/she will 
only compile his/her program with gcc, why shouldn't he/she be able to use 
such features??

Or don't you think, this is a good feature?- If yes, why?

Thanks for your help!

Best regards,

Robert