[Insight-developers] Protected virtual functions made public

[Julien Malik]

Hello,

I've been seeing a recurrent bug through ITK (initially I saw it inside 
Orfeo Toolbox) : some filters change the visibility of protected 
functions of ProcessObject.

For example, take the probably most used class of ITK : ImageFileReader.
Its GenerateOutputInformation is public, whereas it is protected in 
ProcessObject.
Another candidate is itk::MultiResolutionPyramidImageFilter for example. 
I'm sure we can find some others.
We do have this problem in numerous classes in OTB.

As GenerateOutputInformation and UpdateOutputInformation have very 
similar names, it is very easy for a end-user to be mislead and use the 
wrong one when it has been made public (by mistake) by the developer.

It seems weird to me that gcc does not even warn about this situation 
(though it is standard C++).
A good pointer is :
http://stackoverflow.com/questions/2143933/how-to-prevent-derived-class-from-making-a-private-protected-virtual-function-pub
It seems like there is nothing to get from gcc (you can compile the code 
with -Wall -Wextra -Weffc++, and still get no warning)

Does someone have a solution for this easy-to-go-wrong case ?
Are there other compilers which warn about this (I'm thinking about 
clang for example) ?


Julien